WO2005018797A2

WO2005018797A2 - Organised assembly of particles and the use thereof as a labelling system

Info

Publication number: WO2005018797A2
Application number: PCT/FR2004/002128
Authority: WO
Inventors: Jean-Louis Viovy; Eléni PSYCHORI
Original assignee: Institut Curie; Centre National De La Recherche Scientifique
Priority date: 2003-08-14
Filing date: 2004-08-11
Publication date: 2005-03-03
Also published as: WO2005018797A8; WO2005018797A3; FR2858852A1

Abstract

The invention relates to an assembly of particles which are interlinked in a linear or branched manner, characterised in that said particles belong to at least two sub-assemblies that can be identified by at least one property that is specific to each sub-assembly, and succeed each other according to a pre-determined sequence that forms part of a specific code. The aim of the invention is to provide a novel labelling system that can be used to unequivocally mark all kinds of objects, whether they may be biological, natural or artificial materials or compounds.

Description

Organized assembly of particles and its use as a labeling system The present invention mainly relates to an assembly of particles particularly useful as a labeling or coding system for natural or artificial objects or products. With the development of an increasingly complex world, traceability and identification are playing an increasingly important role. In particular, traceability, which allows unambiguous identification of the origin of a product, represents an important issue in terms of security. For example, it is important to know the origin of a food. It can also be important to be able to unambiguously identify an object or material, to detect counterfeits, whether for products, official documents, checks or banknotes. Likewise, it may be important to uniquely identify a material, for example to allow its recycling or to know its manufacturer. Various labeling methods have already been developed for this purpose. The most common are printed or engraved patterns on the surface of the object in question. As an illustration of this surface labeling method, mention may in particular be made of bar codes, patterns printed on banknotes or official documents. However, regardless of the care taken to make these documents unforgeable, counterfeiters equipped with suitable printing tools always end up making counterfeits that are difficult to detect. Furthermore, these impressions concerning the surface of objects, they are relatively fragile and generally bear poor abrasion or even melting of the object, if it is for example a plastic material. As an alternative and to partially replace these limits of use, it has been proposed to integrate identification criteria into the mass, and no longer only at the surface, of the objects to be marked. These are, for example, fluorescent markers or watermarks for banknotes. Here again, however, some counterfeiters manage to overcome these obstacles and, for example, obtain fluorescent markers with a spectrum comparable to that of banknotes. Another alternative resulting from microelectronics, consists in integrating, for example magnetic fields or “chips”, in the considered objects. This type of marking is widely used for example in “magnetic cards” and “smart cards”. However, numerous miscellaneous facts have shown that it was possible, for well-equipped counterfeiters, to program or reprogram magnetic or chip cards. Furthermore, these technologies are quite expensive and cumbersome, and their applications therefore remain limited to multi-use cards. Finally, they are quite fragile and do not withstand strong deformations, for example. There therefore remains to this day a need for a labeling method capable of being integrated into an object and which makes it possible to identify the origin of it in a safe manner even if the latter has been reduced to pieces or partially destroyed. In addition to the areas of use mentioned above, the field of science and more particularly that of the life sciences is also likely to benefit from such a labeling system. Indeed, the development of genomics and proteomics, or that of combinatorial chemistry generally involves the parallel analysis of thousands or even millions of products. For obvious reasons, it would be particularly advantageous to be able to identify the products in question in a simple manner during these analysis operations. However, this follow-up of analysis is all the more difficult as these analyzes are generally carried out with quantities of sample and reagent as reduced as possible. Under these conditions, it is very difficult to be able to carry out an analysis of a large number of different dispersed species, in a mixture. One solution, which can be used for biomolecules such as nucleic acids or proteins, consists in using "DNA chips", "nucleic acid chips" or "protein chips". In "nucleic acid chips", DNA molecules or oligonucleotides (probes) are deposited or synthesized in situ in predetermined "spots" on a surface. Each spot has a typical surface of 100 microns by 100 microns or less, and contains a unique type of nucleic acid. This surface is placed in the presence of the sample to be analyzed, under conditions allowing the formation of a double helix of nucleic acid. If the sample contains a nucleic acid complementary to that fixed on a spot, this “target” nucleic acid will hybridize and this hybridization can be detected, most often by fluorescence, or by other techniques. This method makes it possible to have a large number of recognition sites over a limited area and therefore to perform a large number of molecular analyzes with a relatively small amount of sample. However, these “chip” type systems, also called “hybridization networks”, present certain disadvantages. Thus, such a system implies that a different nucleic acid is deposited or synthesized on each spot, and this for each "chip" which makes the manufacturing expensive and therefore the price of these "chips" very high. Finally, the kinetics of hybridization is significantly slowed down compared to a conventional hybridization in solution. In WO 00/71243, it is proposed to test analytes, using a network of microspheres arranged on a surface, the microspheres being carriers of different functionalities. However, this identification mode involves depositing each type of sphere in predetermined locations beforehand, so that we can then identify with which probe a target has interacted. A variant, proposed in Kohara et al, "Micro Total Analysis Systems 2002", Voll, pp 227-229, Y. Baba et al. Eds, Kluwer Académie Publishers consists in organizing linearly individualized beads in a capillary. Each bead has a different type of oligonucleotide on its surface, thus making it possible to compare, in the same channel, a sample with several types of oligonucleotides. However, as in WO 00/71243, it is necessary to introduce the balls one by one into the channel. Furthermore, the presence of a microchannel to catalyze the beads and maintain their order is essential. All this raises many constraints in terms of microfluidics. To partially compensate for this drawback, it has been proposed in US 5,981,180

(Luminex), first of all to constitute a set of balls grouping together several sub-sets of balls. In each subset, the beads, individualized with respect to each other, carry a ligand specific for a species to be analyzed as well as a unique combination of fluorescent markers. The set of beads is then placed in the presence of the sample containing the species to be analyzed, for a time sufficient for each species complementary to a ligand characterizing one of the sub-families of beads to hybridize to the beads of this sub- family. The set of beads is then analyzed by flow cytometry, according to a mode making it possible to simultaneously measure for each bead the fluorescence light emitted in several wavelengths and to identify unequivocally the beads belonging to each of the subspecies and the quantity of analytes linked to said beads. This method is elegant and efficient for analytical applications, but its multiplexing capacities remain limited: indeed, the spectra emission of fluorescent molecules are quite wide and it is difficult or impossible to use a large number if one wishes to prevent any overlap at the level of these spectra or to be free from any uncertainty on the identification of the corresponding ball . More recently, the document WO 01/25002 describes colloidal particles in the form of rods, that is to say of linear shape, made up of several segments of different and contiguous conductive metals. Each metal segment can be characterized by a property which is specific to it such as its dimension or its reflectivity properties. All of the segments thus constitute a code which makes it possible to identify it with a much richer combination than that of the systems proposed in document US 5,981,180. However, such systems also have drawbacks. In particular, the density of metals being high, these metal rods tend to sediment quickly when they are suspended in water or in aqueous solutions. Furthermore, very small metal particles other than those made of noble metals are rapidly corroded in water and in most biological buffers. Consequently, to effectively implement the invention proposed in WO 01/25002, it is most often necessary to use particles made from gold, platinum or silver, and therefore expensive. Finally, said particles are limited to a small dimension, typically at most about fifty microns, by their manufacturing process and by their rigidity which makes them fragile for larger dimensions. Consequently, for the reasons mentioned above, there does not yet exist, also in the field of life sciences, a labeling system giving total satisfaction in terms of cost, simplicity of implementation and reliability. . The object of the invention is precisely to propose a new labeling system, useful for unequivocally marking any type of object, whether it be materials or biological, natural or artificial compounds. More precisely, the present invention relates, according to a first of its aspects, to an assembly of particles linked together linearly or in a branched manner, characterized in that said particles belong to at least two subsets identifiable by at least one property specific to each subset, and follow one another according to a predetermined sequence constituting a specific code. The invention relates in particular to a linear or branched assembly of particles permanently linked to each other, said assembly having along its length a succession of predetermined properties carried by the particles, said succession constituting a code characteristic of said assembly. This code is said to be characteristic insofar as it makes it possible to distinguish the assembly considered with respect to other assemblies comprising either other properties or the same set of properties but with these arranged in a different order of succession. . More particularly, the particles are bonded permanently or even irreversibly and in a linear form in the assemblies according to the invention. For the purposes of the invention, the term “chain of particles”, or “linear assembly of particles”, can be interchangeably referred to as an assembly of particles linked together so as to constitute an object having at least locally an elongated shape, it being understood that the architecture of this assembly is not made up or imposed by a support preexisting to said assembly of particles, such as a wire, a surface, a ribbon, or any other physical element not constituting the particles themselves on which the particles would be attached, but on the contrary is formed directly by the cohesion of the particles between them. According to a preferred variant, this cohesion is ensured by one or more covalent molecular bonds as described below. Different examples of such particle chains according to the invention are presented in Figures la to ld. They can thus be in the form of a "pearl necklace", in which the width of the chain is essentially that of a particle, as shown in FIGS. 1a, 1c, or 1d. They can also be presented in “columns”, in which each section of the chain contains several particles. In all cases, the linear assemblies of particles according to the invention have an aspect ratio (ratio of length to the largest dimension of a section) significantly greater than 1, typically greater than 3, and in particular greater than 5 However, for many applications, significantly higher aspect ratios, of 10 or more, or even greater than 100 and up to 10,000, may also prove to be advantageous. Also within the scope of the invention is a branched assembly of particles comprising several linear chains linked together, provided that one at less of said chains has an aspect ratio greater than 3, and in particular greater than 5. An example of such a branched chain according to the invention is shown in FIG. Whether in the form of a linear chain (s) or of a branched chain (s), the assemblies according to the invention are clearly distinguished from compact three-dimensional aggregates of particles in which the organization of the particles between them is completely arbitrary and therefore not reproducible. The assemblies according to the invention can have very variable dimensions, in terms of average diameter and length. Typically, their average diameter varies from 10 nm to 1 mm, in particular from 10 μm to 400 μm, and very particularly from 10 nm to

100 μm, in particular still from 100 nm to 5 μm. Their length typically varies from

200 nm to 5 mm, in particular from 200 nm to 500 μm, and in particular from 1 μm to 100 μm. In general, the section of the particle assemblies according to the invention is essentially circular. However, it can also be of any other form, insofar as the largest dimension of this section remains less than the greatest length of the colloidal chain by a factor of at least 3. Several methods known from the Those skilled in the art can be used to measure the flexibility of microscopic linear objects such as those used in the invention. A simple method consists, for example, in allowing a diluted suspension of assemblies according to the invention to evaporate on a transparent support, then observing these under a microscope. If the assembly is made up of micrometric particles (typically between 500 nm and a hundred microns), the simplest method consists in depositing the assemblies on a microscope slide, and observing them by microscopy.

For example, we can observe by this method that the particle assemblies presented in Figures 4a, 4b and 4c, are of the semi-rigid type: they indeed have several curved zones, whose local radius of curvature is comparable to the length of the assembly. By "comparable" is typically meant a radius of curvature between 10 times the length and 0.2 times the length of the assembly. For more precise measurements and to perform statistics on a large number of particles, it is also possible to automatically determine the assembly axis and its radius by automated image analysis software. For some assemblies of smaller sizes, for example of diameter less than 500 nm, it may prove to be more precise to use an electron microscope instead of an optical microscope. In this case, the assemblies are preferably deposited on an electron microscopy grid and shaded with a technique known to those skilled in the art, such as the deposition of carbon or metal. The particle assemblies according to the invention can be relatively rigid (essentially taking the form of a rod), as shown in FIG. 1a, semi-rigid (capable of reversibly having a radius of curvature comparable to their length), as shown in Figure 1d, or flexible (capable of reversibly having a radius of curvature much less than their length), as shown in Figure le. In the case of flexible chains, the length in the description above is understood along the curvilinear abscissa of said chain. According to a preferred variant, said assemblies of particles according to the invention are flexible or semi-rigid. In other words, in the context of the present invention, non-monolithic assemblies are preferred. Indeed, such assemblies are advantageous for several reasons. On the one hand, they slide more easily towards each other. On the other hand, they are at rest in a folded form and as such occupy less space and are more easily kept in suspension without them becoming entangled. Finally, they can be easily aligned in a flow, for example in the flow chamber of a flow cytometry device. This last property is particularly significant for semi-rigid assemblies which therefore constitute a particularly privileged compromise. According to a particular embodiment of the invention, the claimed particle assemblies are organized linearly so as to form an irreversible chain or a set of irreversible chains of particles. For the purposes of the present invention, the term irreversible is intended to characterize the inability of the linear chains of the particles to loosen spontaneously and / or at short notice in the absence of an external field. In this case, chains of particles whose linear organization requires the permanent maintenance of an external, magnetic or electric field, are excluded from the field of the invention. The irreversible nature of the particle assemblies according to this particular embodiment of the invention is understood, however, under given conditions of composition of the fluid in which they are suspended. Thus, such assemblies will be considered as irreversible, even if it is possible to dissolve them by diluting them in a liquid of composition or pH significantly different from that of the liquid in which they were formed. Within the meaning of the invention, the term “particle” means any compact three-dimensional object made up of a multitude of atoms or molecules, and capable of being kept in suspension in a fluid. The dimensions of a particle according to the invention are typically between a few tens of nanometers and a few hundred microns, typically between 10 nm and 400 μm, in particular between a hundred nanometers and ten microns, typically between 100 nm and 150 nm. By way of example, latex spheres, microgels or magnetic beads of micron or submicron dimension, nanocrystals or isolated microcrystals constitute particles within the meaning of the invention, since their mode of production allows them obtain or suspend them in a fluid. The particles used to constitute the assemblies according to the invention are preferably of essentially spherical shape, for example in the form of beads. By essentially spherical shape is meant an object which appears visually as a slightly or not deformed sphere, typically having spherical defects of less than 30%, and preferably less than 15%. This form has several advantages. On the one hand, it is easy to obtain commercially spherical colloidal particles, generally called "microbeads" or "nanobeads", or even "latex", already carrying different properties such as different colors or different absorption spectra or fluorescence emission, and also carrying on their surface chemical or biological functions useful for applications. On the other hand, spherical particles generally tend to form, when they are aligned in an electric or magnetic field, a more regular chain than anisotropic particles, which can associate with each other with different orientations. Advantageously, the particles used for the preparation of assemblies according to the invention are of homogeneous composition. Alternatively, they can however, be coated on the surface with one or more layers of separate compositions. In all cases, however, that is to say if one disregards this possible coating, the particles used for the preparation of assemblies according to the invention are not multisegmented in terms of composition. More precisely, they do not consist of a chain of several segments of distinct compositions. Preferably, the particles used to form the assemblies according to the invention have a low polydispersity in size, in particular less than 2 and in particular less than 1.5. As indicated above, this allows for more regular assemblies. For the purposes of the invention, the term "property" means a characteristic in particular physical, chemical, optical, electrical, magnetic or biological, measurable or detectable, which makes it possible to differentiate the particles from one another. For example, these properties may be optical properties (absorption or emission of light, fluorescence, or luminescence (color), or more generally properties arising from interaction with electromagnetic or radioactive radiation, magnetic properties, properties of dimension, shape, or density. According to a first variant, these properties are properties pertaining to interaction with electromagnetic radiation. According to a second variant, the properties held by the particles are optical properties. variant, these properties relate to the light absorption spectrum. According to another variant, said optical properties are fluorescence emission properties at one or more predetermined wavelengths, under the action of an excitation at one or more several predetermined wavelengths. According to another variant also preferred ée, said optical properties relate to the luminescence emission spectrum, or luminescence properties at one or more predetermined wavelengths, spontaneously or under the action of a stimulus such as the presence of a substrate or the application of an electric field. By “code” is meant in the sense of the invention to refer to the sequence of all the properties present within the assembly of the particles and in particular along the said linear chain of particles. By way of example, and according to a so-called “digital” coding mode, the chain in FIG. 1a represents an assembly of particles characterized by the property code ABBACAB, where A, B and C represent different properties, for example colors different. With the exception of branched chains, the codes within the meaning of the invention are reversible along the chain, that is to say that the code ABBACAB for example, is equivalent to the code BACABBA. As another example, the string in Figure 1d represents the code ABBCABCA. It is also possible, within the framework of the invention, to use another so-called “global” coding variant using the succession of properties along the chain, without taking into account the number of particles exhibiting said property. According to this reading mode, for example, the assembly presented in figure 1a responds to the code ABACAB, and that presented in 1d corresponds to the code ABC ABC A. This more general coding mode turns out to be more particularly advantageous when the detection method used to read the code is not very precise, when the particles are very small and / or when the manufacturing method of the assemblies does not allow to ensure with certainty a fixed number of consecutive particles having a given property. One can likewise use an intermediate coding mode, called "analog", taking into account the succession of different properties carried, not by each particle, but jointly by several particles over a certain length. In this variant, the coding can relate both to the order of succession of the properties, and to the length of the chain assigned to one or more of the properties considered. For example, the chain shown in Figure lb is characterized by the code A (11) B (12) C (13) A (14), where 11, 12, 13 and 14 are, respectively, the lengths over which the chain consists of particles carrying the properties A, B, C and A. This coding mode is particularly suitable for strings in "column", as shown diagrammatically in FIG. 1b, or also for particles of small size. In the case of branched strings, the code may have a more complex structure. The branched chain of figure le, for example, carries, according to a coding mode called "digital", the code ABC (AB) BAAB (CCA) CC, according to a notation in which the first parenthesis represents the code carried by a sub -chain carried by the third particle of the main chain having the property C, and the second parenthesis contains the code carried by a second substring, carried by the seventh particle of the main chain, carrying the property B. The ramifications advantageously make it possible to considerably increase the number of possible combinations. The particles used to form the chains according to the invention can be organic, mineral or organomineral. As already specified above, many types of organic or organomineral particles are commercially available or known to those skilled in the art. They make it possible to construct colloidal chains according to the invention endowed with very diverse properties. In the case of the present invention, the particles can advantageously be dielectric, non-conductive particles compatible with alignment by electric field. It can also be magnetic particles compatible with alignment in a magnetic field. Also suitable for the invention are particles consisting at least in part of organic polymer such as, for example, macromolecular polymers and materials. According to a preferred variant, they are wholly or partly of an organic nature, or of an organomineral nature, that is to say having both organic constituents and mineral constituents. Many types of organomineral particles are commercially available or known to those skilled in the art. They advantageously make it possible to combine properties originating from the organic part and properties originating from the mineral part, and therefore to construct assemblies of particles according to the invention endowed with very diverse properties. As regards the chemical nature of the mineral part (or of the whole of the particle if it is essentially mineral), it can also be very varied, and in particular comprise “quantum dots” endowed with specific properties of fluorescence or d absorption of light, and / or dielectric materials such as metal oxides or semiconductor metals. Magnetic materials, such as superparamagnetic, ferrimagnetic, ferromagnetic materials are very particularly suitable for the invention. As semiconductor oxides, particles essentially consisting of silicon oxide or silica or comprising a silica shell are particularly advantageous. As regards the chemical nature of the organic part of said particles, it can also be very diverse, and in particular comprise, by way of example, vegetable oils, of petroleum origin or of synthesis, various polymers such as acrylamide, polystyrene, polycarbonate derivatives, crosslinked or not, and more generally all the materials used to form latexes. Particularly suitable for the invention are particles comprising an inorganic core coated with an organic layer of polymer type such as for example, polymers of polystyrene, polycarbonate, or derived from monomers of acrylic type such as N-isopropylacrylamide, glycidyl acrylate or methacrylate, 2-hydroxyethylmethacrylate (HEMA), or ethylene dimethacrylate (EDMA). It can also be polymethylmethacrylate. An organic envelope is particularly advantageous insofar as it offers, via the presence of its organic surface functions, grafting possibilities for recognition sites and / or ancillary compounds and facilities for the linear organization of said particles. All kinds of reactive functions, well known to those skilled in the art, can be used as surface reactive functions. They may be, by way of example and without limitation, carboxylic, amino, alcohol, thiol functions, polymerizable functions such as double or triple bonds, in particular the allyl or acrylic functions, or alternatively polyols, hydrazines and / or epoxides. They can also be strong binding sites for transition metals, such as "histidine cages" for nickel. Of course, it is advantageously possible to use, within the framework of the invention, particles having any combination of the privileged characteristics set out above, such as, for example, particles which are at the same time organomineral, dielectric and magnetic, and having various functions of surface. Advantageously, the particles are chosen so as to give the linear assemblies according to the invention a density less than 2. In particular, this density is less than 1.8 and more particularly less than 1.6. Ideally, this density can vary from 0.7 to 1.4. These different variants are particularly advantageous when said assemblies must be, for a certain time, kept in suspension in a fluid, and in particular an aqueous fluid, as is the case for biological applications. Indeed, in these applications, a low density prevents assemblies from sedimenting, promotes their interaction with the targets with which they must react, and makes their subsequent analysis, for example by flow cytometry, easier. As specified above, the particles are organized within the assemblies according to the invention so as to form a predetermined sequence characteristic of a specific code. More particularly, these particles are organized in the form of at least one linear chain, where appropriate carrying one or more branches. Such an organization implies maintaining a cohesion between said particles. This cohesion allows the chains of particles to be maintained in suspension, deposited on a surface, or dispersed in a matrix, without altering the sequence of properties appearing the code which makes it possible to identify them. In the chains of particles according to the invention, the cohesion between the particles can be ensured by covalent bonds, in particular established directly or not between said particles. Indeed, these links can also result from a bypass using molecules or macromolecules. More generally, this valid link involves specific interactions either directly between said particles or between particles and molecules or macromolecules, via reactive functions present on the surface of these particles. The reactive functions can be amine, carboxylic, alcohol, aldehyde, thiol, epoxide, hydrazine, halogen atoms and / or double bonds. However, the constitution and maintenance of a linear organization between the particles can also bring into play electrostatic, hydrophobic or Van der Waals type interactions. They can also be obtained by interpenetration between polymers initially carried by different particles. For certain applications, in particular for the analysis of species or biological fluids, it may be advantageous for the particle chains according to the invention to carry, on their surface, molecules capable of avoiding non-specific adsorption phenomena . Such molecules are well known to those skilled in the art. They may in particular be hydrophilic polymers such as polyxyethylene, polypropylene glycol, polysaccharides and in particular dextran or polyacrylamide, or hydrophilic acrylamide polymers, such as "Duramide", poly-N-acryloylamino-propanol, poly-N-acryloylaminoethanol, polyvinyl alcohol , polyvinyl-pyrrolidone, polydimethylacrylamide or copolymers of dimethylacrylamide and allyl-glycidyl ether. Such polymers can be grafted onto the surface of the particles either during the preparation of said particles, or after the formation of said chains, using reactive functions integrated into the surface of said particles, or by direct adsorption. The presence of a bond between the particles, preferably irreversible, and in all cases sufficient to ensure cohesion between said particles for a period sufficient for the use that one wishes to make of the assemblies according to the invention, in l absence of an external field or of a channel confining said particles, gives the invention significant advantages, for example compared to the balls of the prior art discussed above. In fact, the assemblies according to the invention prove to be perfectly compatible with use both in volume and in a channel. Furthermore, if one chooses to use said assemblies in a microchannel, one can in the same microchannel implement a large number of these assemblies, which is advantageous in terms of number of analyzes. According to a preferred variant, particularly advantageous for the analysis of species, the assembly of particles according to the invention can also carry at least one type of recognition site (s) for a species. Within the meaning of the invention, the term “species” means molecules or macromolecules, particles, atoms, ions, objects of natural or artificial organic origin, such as nucleic acids, proteins, enzymes, antibodies, antigens, peptides, polypeptides, haptens, polysaccharides, proteoglycans, organelles, viruses, cells, sets of cells, microorganisms and colloids. It can also be nanoparticles or microparticles of natural or artificial origin, organic or organomineral molecules, drugs, drugs, food, veterinary or cosmetic products and pollutants. By recognition site, or “probe” means a molecule, an ion, a surface element, or even a specific portion of a molecule or an ion, capable of giving rise to an attractive interaction or a chemical reaction with a particular species or a particular category of species. The recognition sites present on the particle chains according to the invention can also be chosen from chemical functions capable of specifically recognizing other chemical species, for example by binding to them (as, for example, crown ethers capable of bonding transition metals or vice versa). They can also be constituted by specific metal ligands, molecular fingerprints, catalytic sites, hydrophobic groups or more generally the functionalities used in chromatography to give columns a specific affinity for certain species. In particular, the recognition sites, present on the assemblies and in particular the particle chains according to the invention, can be chosen from compounds comprising aromatic or heterocyclic chemical functions, or sites capable of giving rise to hydrogen bonds. Several distinct types of recognition sites may be present at an assembly of particles in accordance with the invention and in particular carried by a linear chain of particles constituting or composing said assembly. However, in the majority of applications, a given assembly of particles according to the invention carries a single type of recognition site, which can be uniquely identified by the code constituted by the sequence of specific properties carried elsewhere by said assembly. This constitutes a decisive advantage for the analysis of species. Indeed, one can prepare in a solution a set of particle assemblies according to the invention, comprising several sub-assemblies of assemblies. Each sub-assembly is characterized by a particular code associated with a specific sequence of properties over its length and the assemblies constituting said sub-assembly also carry a particular type of probe. We can then put this set of particle assemblies, in the presence of a sample containing a set of species (targets), which we want to know if they interact with the probes. Thanks to the presence of a multiplicity of microscopic chains, it is thus possible to test a sample against a large number of probes, as in the techniques known as “DNA chips”, “protein chips”, or RNA chips, or more generally in so-called “network” techniques of hybridization ”, but with, compared to these chips or networks, the following advantages: On the one hand, as the assemblies of particles according to the invention occupy space in three-dimensional manner, it is possible to work with the same average number of probes in a much smaller volume, which reduces the need for sample and reagents, increases the concentration of targets for a given amount of sample and therefore increases the kinetics. The kinetics can be further increased by the fact that the particle assemblies according to the invention can be suspended in a liquid, and can therefore be agitated more effectively than, for example, probes fixed on a surface. The fixation of a target species on a particle chain according to the invention can be detected, using a technique known to those skilled in the art, and in particular by fluorescence, if the targets with a fluorescent marker, or by a chemiluminescence reaction, or also by light absorption properties, this list being given by way of example and without limitation. It is then possible to identify unequivocally the probes with which a given target has interacted, by virtue of the unequivocal association existing between said probes and the code characterizing the assembly of particles carrying said probes. There are many ways to prevent this detection of the fixation of targets on the chains according to the invention from interfering with the recognition of the code: According to a preferred variant, it is possible, for example, to use for coding and for marking targets fluorescent or luminescent markers emitting at different wavelengths or with different time constants, or light absorption markers absorbing at different wavelengths. According to another preferred variant, compatible with the previous one, the code characterizing the chain can be carried by a certain portion of the length of the chains according to the invention, the probes being carried by another portion. Several examples of such assemblies are presented in FIG. 2, where we see: A first assembly, carrying the code AABBCCDDAA and the recognition site V, a second assembly carrying the code BBAAAACCBB and the recognition site T, and a third carrying assembly BBBBDDAABB code and recognition site I Of course, for reasons of simplicity, only a certain number of preferred variants have been described above in which a single type of probe can be unequivocally associated with a single code. However, for other applications, and for example for the development of multiplexing, or else to rely on redundancy in order to reduce the uncertainties, it is possible to use within the framework of the invention a more complex combinatorial between the probes and codes. The subject of the invention is also a set of assemblies of particles linked together linearly or in a branched manner, composed of several assembly sub-assemblies in accordance with the invention, the assemblies belonging to a given sub-assembly being carriers of '' a specific code specific to said subset, in particular defined by a specific sequence of properties along their length, and further carrying at least one type of recognition site (s) specific for said subset. An assembly assembly bringing together three assemblies according to the invention belonging to three different sub-assemblies is illustrated by FIG. 2. The present invention further relates to a process for preparing at least one notably linear assembly of particles linked together, having in its length a succession of predetermined properties constituting a specific code, comprising at least the steps consisting in: A / suspending in a medium, in particular a fluid, particles belonging to at least two subsets identifiable by at least one property specific to each subset, and capable of binding together, B / activating at least one means leading to their organization in said medium in an essentially linear form, and C / obtaining an irreversible bridging between the particles during their state of alignment. The invention also relates to a method for constituting at least one assembly of particles linked together in a linear fashion, comprising at least the steps consisting in: A / preparing a fluid medium comprising monomers capable of binding by polymerization or polycondensation, B / suspending in said medium, particles carrying functions capable of reacting with said monomers, C / activate at least one means leading to their organization in said medium in a linear form, and D / obtain an irreversible bridging between the particles during their alignment state. The invention also relates to an assembly of particles linked together linearly or in a branched manner which can be obtained by one of the two methods described above. As specified above, the methods according to the invention may comprise a preliminary step comprising the introduction into the medium, of molecules capable of binding by polymerization or polycondensation between them and of reacting with said particles. According to this variant, the starting medium can further comprise an initiation system such that the polymerization reaction is not completed at the time of step C but gives rise to a bridging between the particles during their maintenance in an aligned form . According to an equally preferred variant, the ignition system is a redox couple. According to a preferred variant, the monomers are of the acrylic type. Among the monomers which can be used to bridge the particles within the framework of the processes described above, acrylamide is particularly suitable, acrylamide derivatives carrying acid functions and especially acrylic acid, acrylamide derivatives carrying amino functions and more particularly N- (3-aminopropyl) methacrylamide hydrochloride, and the copolymers of these different monomers. According to a preferred variant of the methods described above, said bridging is obtained using a stimulus. This stimulus can correspond to a change in temperature, in particular an increase in temperature and / or to an activation using light, an electric field, a magnetic field, an electromagnetic field, and / or radioactive radiation. In the case where the initiation is carried out by an electromagnetic field, the medium may advantageously contain, in addition to the monomers, a photoinitiator such as, for example, AIBN (Azobis-isobutyronitryl), or methylene blue. For example, we could use methylene blue in the presence of a redox system, as described in

Righetti and Caglio, Electrophoresis, 1993, 14, 573. According to a preferred variant, the methods described above also include a step aimed at recovering, at the end of the bridging operation, said assembly of particles in linear form. When the particles are particles formed for all or part of silica, it is advantageous to use for the bridging between these particles acrylic monomers in the solution, and to functionalize the surface of the particles with double bonds, either by using macromonomers with properties d surface adsorption, such as for example poly-dimethylacrylamide molecules carrying a double bond at their end, either by grafting on the surface of said particles a silane having a polymerizable function, such as trimethoxyxilyl 3-propylmethacrylate (Bind silane , Aldrich). When the particles are latex particles carrying amino functions, it is advantageously possible to use, in the suspension of step A, acrylic or allylic monomers, optionally added with a redox initiator couple and / or with a photoinitiator and a photoactivator, and activate the particles beforehand with N-hydroxysulfosuccinimide (Sodium salt, Fluka), optionally supplemented with 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide (sigma)). A particularly advantageous method for preparing large quantities or even a multiplicity of assemblies of particles linked together, said assemblies having, according to their length, a succession of predetermined properties according to the invention, comprises at least the steps consisting in A / preparing in a first container of particles identifiable by at least one property specific to these particles, or a composition comprising particles and at least one reagent making it possible to confer, over time or under the action of a stimulus to said particles, such a property, B / prepare in at least a second container particles identifiable by at least one specific property, or a composition comprising particles and at least one reagent making it possible to impart, over time or under the action of a stimulus to said particles property, said property being different from that characterized ant the particles or the reagents contained in the first container, C / introduce into a microchannel, by at least two distinct arrival channels, the solutions prepared in steps A and B, and possibly others solutions by other inlet channels, so that said solutions form in the main channel essentially laminar and parallel liquid veins, D / activate, within said channel, at least one means inducing the organization of the particles in linear chains, E / link the particles together in their linear state, and F / recover said assembly thus obtained. Of course, the method can be applied to a greater number of types of particles and to a greater number of arrival channels. The possibility of having several modes of succession of the particles defining the code characterizing the assemblies, of a greater number of types of particles and of channels allows a more complex combinatory. According to a preferred variant, said means comprise an external field essentially perpendicular to the planes separating the different liquid veins. This variant is particularly advantageous, since it makes it possible to obtain directly along the particle chain, a sequence of properties, predetermined by the properties of the particles or of the markers contained in the different liquids, used to constitute the different liquid veins in the main channel. According to a preferred variant, of the methods described above, the means making it possible to organize the particles in a linear chain include the application of an electric field. According to another preferred variant, said means comprise the action of a magnetic field. According to a third preferred variant, said means comprise the action of an electromagnetic field or of radioactive radiation. According to a fourth preferred variant, said means comprise a hydrodynamic flow. According to a preferred variant, the particles are magnetic and said means comprise the application of a magnetic field. According to another preferred variant, the particles are dielectric and said means comprise the application of an electric field. Preferably, this electric field is alternating, and even more favorably with a frequency between 200 kHz and 5 MHz. To align dielectric particles in an electric field, it may also be advantageous to use a suspension of said particles in a solvent organic such as, for example, ethanol, methanol, acetonitrile, or in a mixture of water and an organic solvent miscible with water. A medium that is less conductive than water is thus obtained, and higher electric fields can be applied without heating, which makes it easier to column the particles. By analogy with the methods defined above, step E is generally carried out according to the protocols proposed above. In particular, step E aims to permanently fix the particles in a linear form. As stated previously, the assembly according to the invention proves to be particularly advantageous for marking objects, in particular fluids or materials. These assemblies constitute efficient marking systems on a microscopic scale carrying a code that is extremely difficult to counterfeit. According to another of its aspects, the present invention therefore also relates to a marking system for an object, characterized in that it comprises at least one assembly or set of assemblies according to the invention. As emerges from the description which follows, these objects can be solid or fluid, in particular liquid and of any kind. By ordering particles carrying these markers, in a predetermined order, within assemblies according to the invention, one can constitute a code having an extremely high number of combinations (10 billion with only 10 different markers and 10 zones along the 'assembly), while conventional fluorescent labeling techniques only present a much more limited number of markers for the same family of markers, due to the superposition of the spectra. The possibility of spatially distinguishing the different types of marker is a decisive advantage, which can be easily taken advantage of with an epifluorescence microscope, a confocal microscope, or “scanner” type systems. On the other hand, unlike for example "bar codes", the particle chains according to the invention can be very small, typically of microscopic dimensions. Thus, they can be dispersed within or on the surface of a material such as for example a plastic material or a paper, and allow its identification even after the object has been broken or even melted. This offers new advantageous tools for industrial and food traceability, waste recycling, police or military applications, or prevention of counterfeiting. Likewise, the subject of the invention is also a method useful for marking an object, in particular a fluid, or a solid of the commodity type or a material, characterized in that it comprises the association with said object, of at least one linear or branched assembly of particles, having in its length a succession of predetermined properties carried by the particles, said succession constituting a code specific to said assembly. More specifically, this method can implement as a marking system, an assembly or a set of assemblies in accordance with the invention. The code shown by said assembly makes it possible to differentiate it from other assemblies comprising either other properties or the same set of properties but with these arranged in a different order of succession. This association with the object to be marked can be achieved by dispersing said assembly either on the surface or within said object. Of course, one can also use in the implementation of the assemblies according to the invention, a multiplicity of different assemblies to increase the number of possible combinations, or perform coding according to several criteria. However, in many applications concerning marking, the combinatorics allowed by the assemblies according to the invention is sufficient to authorize the use of only one type of assembly per product. The invention also relates to a method for detecting or analyzing assemblies of particles as described above, as well as the recognition of species by said assemblies. These methods can use various means known to those skilled in the art. According to a preferred variant, it is carried out by conventional or confocal microscopy, after depositing the chains according to the invention on a surface. According to an even more preferred variant, said chains are deposited in the presence of a flow or by passage of a meniscus, as in Bensimon et al, Phys Rev Lett. 1995, 74, 4754-4757. They are thus all aligned in the same direction, and thus easier to analyze automatically. According to another preferred variant, this detection can be carried out by flow cytometry. The assemblies and in particular the chains according to the invention are particularly advantageous in combination with flow cytometry. Indeed, on the one hand the flow tends to align the chains, and on the other hand the different particles constituting a chain, pass in front of the detector sequentially. Double information is thus available for the analysis, both on the light emission properties and on the time sequence of these properties, which constitutes a major advantage compared to the techniques of the prior art discussed above. . Another subject of the present invention, according to another of its aspects, is a method for analyzing, identifying, dosing, purifying or preparing a sample, implementing at least one step consisting in bringing said sample into contact with at least one assembly of particles according to the invention. Optionally, this method further comprises a washing step during which certain products contained in the sample are eliminated and / or during which certain products are recovered. Another subject of the invention is, according to another of its aspects, a method for analyzing the interaction of species contained in a sample with respect to a multiplicity of recognition sites or probes, comprising at least the steps consisting in: : A / bringing together said sample, with a set of assemblies of particles linked together linearly or in a branched manner, composed of several subsets, each subset being characterized by a code and by at least one type of site of recognition which are specific to it, and B / research and possibly quantify the fixation of species on at least some of said subsets of assemblies. By way of example and without limitation, the assemblies of particles according to the invention, and the various components and devices implementing said assemblies, can be used for: - in vivo or in vitro diagnosis, identification and / or the preparation of molecules, macromolecules, particles, atoms, ions, objects of natural or artificial origin such as nucleic acids, proteins, enzymes, antibodies, peptides, polypeptides , polysaccharides, proteoglycans, organelles, cancer cells, rare cells, epithelial cells, endothelial cells, fetal cells, genetically modified organisms or products derived from genetically modified organisms, organisms or pathogens , viruses, microorganisms; identification and / or preparation of chemical active ingredients such as toxic products, drugs, pollutants; drugs, food supplements. recognition of plant animal varieties or microorganisms; - detection of mutations; the search for allergies; genotyping; the search for genes involved in diseases; research and / or preparation of reaction products from combinatorial chemistry protocols. By way of example and without limitation also, the assemblies of particles according to the invention can be used for identification purposes for: marking industrial, strategic or food products, packaging, liquids, materials, plastics, paper and cardboard, weapons, vehicles for traceability purposes, and to be able to identify their origin a posteriori, and mark monetary and fiduciary tools such as banknotes, credit cards or checks , official documents such as passports, passes, identity cards, products covered by brands and models or copyrights such as clothing, leather goods, audio or audiovisual media such as CD or DVD, in order to identify possible counterfeits. The examples and figures which follow are presented by way of illustration and without limitation of the field of the invention. Figures Figure 1: Variants of particle assemblies according to the invention. la: rigid linear assembly, of the “pearl necklace” type, carrying the digital code “ABBACAB”; lb: rigid linear assembly, of the “column” type, carrying a code combining property information of the particles and length information assigned to said property. The code carried by this specific example is A (11) B (12) C (13) A (14), where 11, 12, 13 and 14 are, respectively, the lengths over which the chain consists of particles carrying the properties A, B, C and A. le: assembly of the “pearl necklace” type, flexible, ld: assembly of the “pearl necklace” type, semi-rigid. the: Branching of the “pearl necklace” type, branched. The particular assembly represented carries the digital code ABC (AB) BAAB (CCA) CC, according to a notation in which the first parenthesis represents the code carried by a substring carried by the third particle of the main chain having the property C, and the second parenthesis contains the code carried by a second substring, carried by the seventh particle of the main chain, carrying the property B. Figure 2: Schematic representation of three assemblies of particles according to the invention, combining a code and a type of recognition site for one or more species. We present, from top to bottom: A first assembly, carrying the digital code AABBCCDDAA (or the global code ABCDA) and the recognition site V, a second assembly carrying the digital code BBAAAACCBB (or the global code BACB) and the site recognition T, and a third assembly carrying the code BBBBDDAABB and the recognition site I Figure 3: Schematic diagram of a microfluidic cell for the manufacture in large quantities of assemblies of particles carrying a particular code, from particles magnetic carriers of specific properties A, B, C, D in a predetermined order and of a type of recognition site T. FIGS. 4 and 5: Different assemblies of particles carrying specific absorption and fluorescence emission properties, prepared according to Example 1 and displayed according to Example 2.

Example 1: Preparation of chains of magnetic particles, carrying a code constituted by a succession of different colors in fluorescence. A / Preliminary, 100 microliters of a suspension containing 1% of a sample of fluorescent magnetic beads carrying amino functions and having predetermined fluorescence properties are selected: In this example, a 1: 1: 1 mixture is more particularly chosen 2.6 μm beads, amino, "Yellow", ref PFAM-2052, 2, μm, amino, "pink", ref PFAM-2058, and 2.5 μm, amino, non-fluorescent, ref PMN-2,5 (Kisker GbR). The beads are washed 5 times with 0.1 M phosphate buffer at pH 7.3 by sedimenting them with a magnetic separator (Dynal) and resuspending them in the buffer. The beads are resuspended in 100 microliters of a phosphate buffer solution of pH 7.3 at 0.1 M, containing EDC (1-ethyl-3- (3-dimethylaminopropyl) carbodiimide (sigma)), 15 mg per 10 ml and S-NHS

(N-hydroxysulfosuccinimide (Sodium salt, Fluka)), 2.5 mg / 10 ml, prepared immediately before use. The mixture is stirred vigorously and left to incubate, with gentle agitation, overnight at 4 ° C. B / a solution B, 1% by weight of acrylamide, is also prepared in a phosphate buffer at pH 7.3, which is degassed for at least 2 h. C / the beads prepared in A are sedimented and resuspended in 800 microliters of solution B. The solution containing the beads is degassed for two hours, by bubbling nitrogen through. D / a solution C, of 10% ammonium persulfate, and a solution D, of TEMED at 10% E are also prepared / quickly added to 100 microliters of the suspension prepared in C,

14 microliters of solution C and 14 microliters of solution D. The whole is stirred vigorously. F / the corresponding solution is immediately placed in a cell with parallel faces, in which a magnetic field is created, perpendicular to the faces of the cell, of at least 20 mTesla. G / after one hour of incubation, the magnetic field is interrupted. A large number of linear assemblies of particles according to the invention are obtained, such as those presented in FIG. 2, bridged by polyacrylamide polymers. They can be observed as described in Example 2, or sorted according to the color sequence for later use, by flow cytometry.

Example 2: Observation and determination of the particle assembly code according to the invention, prepared according to Example 1. The assemblies are deposited by sedimentation on a microscope slide, and observed in epifluorescence, in a Zeiss Axiovert 100 inverted microscope equipped with a 100X immersion objective, an epifluorescence device and an intensified CCD camera (LHESA). , (the Ulis). Two fluorescence observation conditions are used: a set of filters 09 from Cari Zeiss, with excitation between 450 and 490 nm (blue), and emission above 512 nm (green and beyond), and a set of filters 15 from Cari Zeiss, with excitation at 546 nm (green) and emission beyond 590 nm. Transmission lighting is also used which makes it possible to see the particles independently of their fluorescence and which can be combined with fluorescence. The three types of particles, non-fluorescent, "pink" and "yellow", are visible in transmission. With the filter set 09, the “yellow” particles, for which it is the optimal absorption, are shiny, and the “pink” particles, fluoresce more weakly. Finally, with the set of filters 15, only the “pink” particles are visible. For the sake of brevity, the letter P will be assigned to the "pink" particles, the letter Y to the "yellow" particles and the letter N to the non-fluorescent particles. Figures 4a and 4b show the same assembly, in transmission (4a) and with the set of filters 09 (4b). Figure 4a gives us the number of particles, 6, and Figure 4b makes it easy to distinguish the two particles Y, very shiny on the left, and the four particles weakly shiny, on the right: the code for this assembly is YYPPP. Figures 4c to 4d show another assembly in transmission (4c), with the filter 09 (4d) and with a combination of the filter 15 and the transmission. In FIGS. 4c and 4e, there are easily 7 particles. Figure 4e indicates that only the second, starting from the left, is P, and we see on 4d that the 3rd and the seventh are also D, since it does not give a signal on 4th. The code is therefore NPYNNNY. Figures 4f to 4h show a set of two assemblies with a different code, in lighting respectively in transmission and filter 15, in filter 09 alone, and in transmission plus filter 15. The top assembly has 5 particles, and meets the code NNNPY, while the bottom assembly has three particles, and meets the code NNP. (we can note on the right an isolated particle, of type N, and below an isolated particle, of type P, and note that they do not interfere with the analysis). It can thus be seen that by combining a limited number of observation conditions, it is possible to unambiguously identify the code of a large number of assemblies according to the invention. The same identification was also made, even easier, using a color camera installed on the microscope.

Example 3: Observation of a branched type assembly. The conditions are identical to those of Example 2, FIG. 5d corresponds to lighting in transmission, and the figure on the right to lighting with the filter 09. The assembly has a main chain of 6 particles, and a branching of two particles carried by the third particle. The code is NNN (YY) NNN. .

Example 4: Serial production in a microfluidic cell This example describes a method of preparing assemblies of particles according to the invention, carrying a code and a type of recognition sites on a zone distinct from the code. This method of preparation is particularly advantageous for obtaining a large quantity of assemblies all having the same code. A / the procedure is as in Example 1 up to step E, but four containers are prepared, containing respectively fluorescent magnetic beads of type P, Y and N, and non-fluorescent magnetic beads carrying streptavidin PMSt-2.0 (kisker, Steinfurt), The different arrival channels 1, 2, 3, 4, 5, 10, are connected respectively to an eppendorf tube containing the solutions of particles Y, N, P, Y, P and streptavidin. The other difference with Example 1 is that the acrylamide solution (solution B in Example 1) also contains methylene blue at the concentration of (100 μM) in the presence of a redox system (1 mM sodium toluene sulfinic acid, and 50 μM diphenyliodonium chloride (Fluka)), B / each container is immediately connected to one of the input channels (1-4) of a microfluidic system such as that represented in FIG. 3 , prepared in PDMS according to Xia, Y. & Whitesides, GM Soft lithography. Angew. Chem. Int. Ed. 37, 550-575 (1998) and a permanent flow of the contents of these containers is induced in the form of a laminar liquid vein in the main channel 12, towards the reservoir of collection 14 by exerting a depression above said reservoir. An inverted microscope, identical to that used in Example 2, is advantageously used to control the good progress of the operations and the formation of the assemblies. An essentially uniform magnetic field perpendicular to the interfaces between the liquid veins, of at least 10 mTESLA, is created using an electromagnet whose pole pieces are machined so as not to create a significant magnetic field gradient in the main channel 12 and in the conduit connecting said channel with the collection tank 14. C / once the steady state is established, the main channel 12 is brightly lit by a UV lamp, in order to induce rapid photopolymerization of acrylamide and particle bridging. There are thus collected in the reservoir 14 assemblies of particles according to the invention, the color code of which is given by the order of the colors of the particles contained in the containers connected respectively to channels 1 to 5, ie in the example proposed here YNPYP (in this embodiment, the liquid veins do not make it possible to control the number of particles in an exact manner, and therefore a coding of the “global” type is used). The presence of streptavidin on the upper zone of the particles is easily verified by incubating the particles with fluorescent biotin (Molecular Probes). D / by repeating the operation by inverting the containers, and by changing the collection reservoir 14, it is thus possible to obtain a large number of assemblies of particles according to the invention, without having to resort to sorting after their synthesis.

Claims

1. Assembly of particles linked together linearly or in a branched manner, characterized in that said particles belong to at least two subsets identifiable by at least one property specific to each subset, and succeed each other according to a predetermined sequence constituting d 'a specific code.

2. Assembly according to claim 1, characterized in that the particles are bonded together permanently and in a linear form.

3. Assembly according to claim 1 or 2, characterized in that it is flexible or semi-rigid.

4. Assembly according to any one of the preceding claims, characterized in that the particles are in essentially spherical form.

5. Assembly according to any one of the preceding claims, characterized in that it has an average diameter varying from 10 nm to 1 mm, in particular from 10 nm to 100 μm, in particular from 100 nm to 5 μm and a length varying from 200 nm to 5 mm, in particular from 200 nm to 500 μm, and in particular from 1 μm to 100 μm. 6. Assembly according to any one of the preceding claims, characterized in that it has a density of less than 2, in particular less than 1,

6, and more particularly varying from 0.7 to 1.4.

7. Assembly according to any one of the preceding claims, characterized in that said particles are linked together by covalent links.

8. Assembly according to any one of the preceding claims, characterized in that the particles are linked together by bridging using molecules or macromolecules.

9. Assembly according to any one of the preceding claims, characterized in that said particles are dielectric or magnetic particles.

10. Assembly according to any one of the preceding claims, characterized in that the particles are organic, mineral or organomineral in nature.

11. Assembly according to any one of the preceding claims, characterized in that the properties held by the particles are properties of interaction with electromagnetic radiation, optical properties of the type emission of fluorescence and / or luminescence or properties relating to the light absorption spectrum.

12. Assembly of particles according to any one of the preceding claims, characterized in that it also carries at least one type of recognition site (s) for a species.

13. Set of assemblies of particles linked together linearly or in a branched manner composed of several sub-assemblies of assemblies according to any one of claims 1 to 12, said assemblies belonging to a given sub-assembly being carriers at the same time at least one type of recognition site (s) specific to said subset and a specific code also specific to said subset.

14. Method useful for preparing at least one assembly of particles linked together, said assembly having in its length a succession of predetermined properties constituting a specific code, characterized in that it comprises at least the steps consisting in: A / put in suspension in a medium, particles belonging to at least two subsets identifiable by at least one property specific to each subset, and capable of binding together, B / activating at least one means leading to the organization of said particles within said medium in a linear form, and C / obtain an irreversible bridging between the particles during their state of alignment.

15. A useful method for constituting at least one assembly of particles linked together in a linear fashion, comprising at least the steps consisting in: A / preparing a fluid medium comprising monomers capable of binding by polymerization or polycondensation, B / suspending in said medium, particles themselves carrying functions capable of reacting with said monomers, C / activating at least one means leading to the organization of said particles within said medium, in a linear form and D / obtaining an irreversible bridging between the particles during their alignment state.

16. A useful method for preparing a multiplicity of assemblies of particles linked together, said assemblies having, along their length, a succession of predetermined properties, characterized in that it comprises at least the steps consisting in: A / preparing in a first container particles identifiable by at least one property specific to these particles, or a composition comprising particles and at least one reagent making it possible to confer, over time or under the action of a stimulus to said particles, such a property, B / prepare in at least a second container of particles identifiable by at least one specific property, or a composition comprising particles and at least one reagent making it possible to confer, over time or under the action of a stimulus to said particles, such a property, the said property being different from that characterizing the particles or the reagents contained in in the first container, C / introduce into a microchannel, by at least two separate inlet channels, the solutions prepared in steps A and B, and possibly other solutions through other inlet channels, in such a way that said solutions form, in the main channel of essentially laminar and parallel liquid veins, D / activate, within said channel, at least one means inducing the organization of said particles in a linear form, E / link them particles in their linear state, and F / recovering said assemblies thus obtained.

17. Method according to any one of claims 14 to 16, characterized in that the said particles are as defined in claims 9 to 11.

18. Method according to any one of claims 14 to 17, characterized in that the assemblies are as defined in claims 1 to 12.

19. Method according to one of claims 14 to 18, characterized in that the said particles bind together directly or by means of a coupling agent, in response to a stimulus corresponding to a change in temperature and / or the action of light, an electric field, a magnetic field, an electromagnetic field, and / or radioactive radiation.

20. Method according to any one of claims 14 or 16 and 17 to 19, characterized in that it further comprises a preliminary step comprising the introduction into the medium of molecules capable of binding by polymerization or polycondensation between them and of reacting with said particles.

21. The method of claim 16 or 20, characterized in that said molecules are monomers of acrylic type.

22. Method according to any one of claims 14 to 21, characterized in that the means inducing the organization of said particles in a linear form are chosen from a magnetic field and an electric field.

23. Object marking system, characterized in that it comprises at least one assembly according to any one of claims 1 to 12 or a set of assemblies according to claim 13.

24. A useful method for marking an object, characterized in that it comprises at least one step consisting in associating with said object, at least one assembly of particles according to any one of claims 1 to 12 or a set of assemblies according to the claim 13.

25. A method for analyzing, identifying, dosing, purifying or preparing a sample, implementing at least one step consisting in bringing said sample into contact with at least one assembly of particles according to any one of claims 1 to 12, or a assembly of assemblies according to claim 13.

26. A method for analyzing the interaction of species contained in a sample with respect to a multiplicity of recognition sites or probes, comprising at least the steps consisting in: A / bringing said sample into contact with a set of assemblies according to claim 13, and B / research and possibly quantify the fixation of species on at least one of said subsets of assemblies identified by their code.