WO2010069296A1 - Means for separating microorganisms on the basis of electrospun fibers - Google Patents

Abstract

The invention relates to composite filters for separating microorganisms from liquids that are contaminated therewith. Composite filters of the invention comprise at least one porous, liquid-permeable support material and at least one nonwoven made from electrospun fibers. The support materials are selected from among fiber-oriented nonwovens, matted nonwovens, porous solids, tissues, paper filters, plastic filters, metal screens, and membrane filters. The electrospun fibers can be water-stable polymer fibers made of synthetic polymers or biopolymers, metal fibers, metal oxide fibers, carbon fibers, or ceramic fibers. In order to produce the composite filters, at least one nonwoven fabric is deposited on the support material/s using the electrospinning technique. The microorganisms that can be separated from liquids contaminated therewith using the composite filters of the invention include archaea, bacteria, viruses, fungi, and protozoa. They also include algae and viruses if they are unicellular organisms or multicellular clusters which are not larger than 0.2 mm. The composite filters of the invention can be used for separating microorganisms from cell culture liquids, industrial and private wastewater and process water, blood plasma, blood serum, and cooling lubricants.

Description

 Agent for the separation of microorganisms based on electrospun fibers

The present invention provides composite filters for separating microorganisms from contaminated liquids. Composite filters according to the invention comprise at least one permeable, liquid-permeable carrier material and at least one nonwoven made of electrospun fibers.

Description and introduction of the general field of the invention

The present invention relates to the fields of macromolecular chemistry, polymer chemistry, biopharmacy and materials science. State of the art

The separation of microorganisms from contaminated liquids plays a major role for technical and private sectors. Under microorganisms Archaeen, bacteria, fungi, algae, protozoa and viruses are understood.

For the production of nano- and mesofibers, the skilled person is familiar with a large number of methods, of which the electrospinning method is of greatest importance at present.This method, which is described, for example, in DH Reneker, I Chun: "Nanometer Diameter Fibers of Polymer , produced by electrospinning ", Nanotechn 1996, 7, 216-223, usually a polymer melt or a polymer solution is exposed to a high electric field at an edge serving as an electrode. This can be achieved, for example, by extruding the polymer melt or polymer solution in an electric field under low pressure through a cannula connected to one pole of a voltage source. Due to the resulting electrostatic charging of the polymer melt or polymer solution, a material flow directed onto the counterelectrode forms and solidifies on the way to the counterelectrode. Depending on the electrode geometries, nonwovens or ensembles of ordered fibers are obtained with this method. While with polymer melts so far only fibers with diameters larger than 1000 nm are obtained, one can produce from polymer solutions fibers with diameters greater than or equal to 5 nm.

DE 100 53 263 A1 describes oriented meso- and nanotube nonwovens which are used inter alia for size separation of viruses and bacteria. However, these nonwovens are not applied to a substrate. With low application strengths such nonwovens are difficult to handle, while high application strengths lead to long filtration times.

DE 101 33 393 A1 describes tubes with inner diameters in the nanometer range, which can also be used for separation techniques. These tubes are also not applied to a carrier material and therefore have the same disadvantages as separation media as the nonwovens according to DE 100 53 263 A1. DE 20 2006 007 518 U1 and DE 10 2006 021 905 A1 describe particle and aerosol filters made of composite materials. The filters contain an absorbent layer of a fabric or a nonwoven, the latter optionally being made by electrospinning. The thickness of the absorption layer is between one micron and 10 mm.

So far, although separation materials are known which comprise or consist of electrospun fibers or nonwovens and with which microorganisms can be separated from liquids contaminated therewith, these materials are either difficult to handle or require very long filtration times. The present invention overcomes these disadvantages by providing composite filters that contain carrier materials and electrospun nonwovens and therefore are easy to handle and allow rapid filtration.

task

The object of the present invention is to provide new means for separating microorganisms from contaminated liquids and to methods for producing these agents.

Solution of the task

The object of providing means for the separation of microorganisms from contaminated liquids is achieved according to the invention by composite filters comprising at least one permeable, liquid-permeable carrier material and at least one nonwoven made of electrospun fibers.

Surprisingly, it has been found that the composite filters according to the invention based on fleeces of electrospun fibers are suitable for the separation of microorganisms from liquids contaminated therewith.

The compositions according to the invention for separating microorganisms from liquids contaminated therewith are referred to below as "composite filters". The composite filters according to the invention based on fleeces of electrospun fibers, the process for their preparation and the use of these composite filters for the separation of microorganisms are explained below, wherein the invention comprises all embodiments listed below individually and in combination with one another.

In the context of the present invention, the term "separation" encompasses both the separation of microorganisms from liquids by means of filtration and the separation of these microorganisms by sizes.

The liquids which can be separated from microorganisms for the purposes of the present invention are aqueous solutions, emulsions, water-miscible solutions (for example cooling lubricants) and oily solutions. An emulsion is understood to mean a finely divided mixture of two immiscible liquids in which one of the two phases is finely distributed in the form of small droplets in the other liquid. The emulsions which can be separated from microorganisms with the aid of the composite filters according to the invention can be both oil-in-water and water-in-oil emulsions.

The term "composite" generally refers to composite materials, Accordingly, composite filters according to the invention are composed of at least one carrier material and at least one nonwoven based on electrospun fibers.

By carrier material is meant a base or base on which the at least one nonwoven on the basis of electrospun fibers is applied. According to the invention filters are used as support materials. Filters are agents that trap solids from a gas or liquid stream.

Nonwovens are generally called loose materials or fabrics of textile or non-textile staple fibers or filaments, the cohesion of which is given by the fibers own adhesion. The term "filament" is used to designate fibers of essentially indefinite length, and filaments obtained by cutting are referred to as staple fibers.

Nonwovens based on electrospun fibers are understood to mean nonwovens according to the above definition, the fibers of which are produced by the known electrospinning process.The nonwovens based on electrospun fibers may consist of one or more layers and optionally these may be based on electrospun fibers with other substances be equipped, for example, those with antimicrobial action.

In contrast, fabrics are textile fabrics made from threads that are crossed at right angles or at right angles. The cohesion of the threads is effected by this very perpendicular or approximately right-angled crossing, the said type of crossing being generally referred to as "weaving." Nonwovens are not woven.

According to the invention, the filters to be used as the carrier material are selected from fiber-oriented nonwovens, random fiber webs, porous solids (for example made from sintered metals), woven fabrics, paper filters, plastic filters, metal sieves and membrane filters.

Filters made of fiber-oriented nonwovens and random fiber webs as well as solid nonwovens and woven fabrics can be made of natural fibers (such as cotton, cellulose, linen, silk, wool), mineral fibers (for example asbestos, glass, mineral wool, basalt) or of artificial fibers, i. made of synthetic polymers, or containing these materials.

Porous solids filters can be made of activated carbon or sintered metals, for example, or contain these materials.

For example, paper filters can be made of cellulose or glass microfibers or contain these materials.

Plastic filters may for example consist of synthetic polymers, glass fibers and mixtures thereof or contain these materials. Membrane filters may consist of, for example, regenerated cellulose, alumina or of synthetic polymers such as cellulose acetate, cellulose nitrate, mixed cellulose esters, polyesters, polytetrafluoroethylene, polyamides, polyethersulfones or polyolefins or contain these materials.

According to the invention, the electrospun fibers are selected from water-stable polymer fibers, metal fibers, metal oxide fibers, carbon fibers, ceramic fibers.

According to the invention, "water-stable polymer fibers" are understood as meaning fibers of such polymers which are substantially water-insoluble

Substantially water-insoluble polymers are, for the purposes of the present invention, in particular polymers having a solubility in water of less than 0.1% by weight. Accordingly, polymers whose solubility in water is greater than or equal to 0.1% by weight are to be understood in the sense of the present invention as water-soluble polymers.

Analogously, for the purposes of the present invention, "oil-stable polymers" are those whose solubilities to an oil are less than or equal to 0.1% by weight .. Polymers whose solubility in an oil is greater than 0.1% by weight are accordingly to understand oil-soluble polymers.

By swelling polymers is meant the liquid uptake by these polymers and a concomitant change in the density and volume of the polymer. As a rule, polymers swell before they dissolve in a solvent. For polymer fibers used for separation purposes, swelling would reduce or even eliminate the separation performance because swelling would clog pores and voids between the fibers. Water- or oil-stable polymers according to the above definitions, however, are essentially non-swellable.

Polymers in the context of the present invention are polycondensates, polyaddition compounds or polymers, but not graphite-like compounds of pure or doped carbon.

If the electrospun fibers are water-stable polymer fibers, the polymers are selected from Poly (p-xylylene); polyvinyl halides; polyvinylidene halides; Polyesters such as polyethylene terephthalates, polybutylene terephthalate, polyvinyl esters; polyethers; polyvinyl ethers; Polyolefins such as polyethylene, polypropylene, poly (ethylene / propylene) (EPDM); polycarbonates; polyurethanes; natural polymers, eg rubber; polycarboxylic acids; polysulfonic; sulfated polysaccharides; polylactides; polyglycosides; polyamides; Homopolymers and copolymers of aromatic vinyl compounds such as poly (alkyl) styrenes, polystyrenes, poly-Q-methylstyrenes; polyacrylonitriles; polymethacrylates; Polymethacrylnitrilen; polyacrylamides; polyimides; polyphenylenes; polysilanes; polysiloxanes; polybenzimidazoles; polybenzobisbenzazoles; polyoxazoles; polysulfides; polyesteramides; Polyarylenvinylenen; polyether ketones; polyurethanes; polysulfones; Polyvinylsulfonen;

polyvinylsulfonic; Polyvinylsulfonsäureestern; inorganic-organic hybrid polymers such as ORMOCER®s of the Fraunhofer Society for the Promotion of Applied Research e.V. Munich; silicones; wholly aromatic copolyesters; acrylates of poly (alkyl); Poly (alkyl) methacrylates; Polyhydroxyethylmethacrylaten; polyvinyl acetates; Polyisoprene, synthetic rubbers such as chlorobutadiene rubbers, e.g. Neoprene® from DuPont; Nitrile butadiene rubbers, e.g. Buna N®; polybutadiene; polytetrafluoroethylene; modified and unmodified celluloses, homo- and copolymers of D-olefins.

Furthermore, the polymers can be water-soluble polymers, such as polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone or hydroxypropylcellulose, if fibers from these polymers are stabilized after electrospinning by a further processing step to water. This further processing step is preferably a crosslinking. This can be carried out, for example, thermally or photochemically, wherein in the case of photochemical crosslinking, the aid of a photoinitiator is particularly advantageous. Further, crosslinking may be by reaction of the water-soluble polymer with a crosslinking agent. These crosslinking agents include, for example, dialdehydes, sodium hypochlorite, isocyanates, dicarboxylic acid halides and chlorinated epoxides. The person skilled in the art knows how to stabilize fibers of water-soluble polymers with respect to water. He can apply this knowledge without departing from the scope of the claims. Furthermore, the polymers may be biopolymers. According to the invention, biopolymers are to be understood as meaning those polymers which are synthesized by polymerization processes from naturally occurring monomer units. In the following, some of these biopolymers are given by way of example but not exhaustively, the corresponding monomer units being given in parentheses: proteins and peptides (amino acids); Polysaccharides such as starch, cellulose, glycogen (glucose); Lipids (carboxylic acids); Polyglucosamines such as chitin and chitosan (acetylglucosamine, glucosamine); Polyhydroxyalkanoates, also referred to as PHB (hydroxyalkanoate); Cutin (C16 and C18 subunits); Suberin (glycerin and polyphenols); Lignin (coumaryl alcohol, coniferyl alcohol, sinapyl alcohol). It is known to those skilled in the art that some of these biopolymers are water-soluble. Water-soluble biopolymers used in the context of the present invention must, as described for the synthetic polymers, be stabilized against water by a further processing step.

Further, they may be copolymers composed of two or more monomer units constituting the aforementioned polymers. These copolymers may be random copolymers, gradient copolymers, alternating copolymers, block copolymers or graft copolymers. All of the abovementioned polymers can be used in the polymer fibers to be used according to the invention individually or in any desired combination and in any desired mixing ratio.

If the electrospun fibers are metal fibers, the metals are selected from the group consisting of Cu, Ag, Au, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Ni, Pd, Co, Rh, Ir. If the electrospun fibers are metal oxide fibers, these are oxides of the metals mentioned.

It is known to those skilled in the art that electrospun metal or metal oxide fibers are made by electrospinning a solution of at least one degradable polymer and at least one metal salt. Metal salts are inorganic or organic salts of said metals. Inorganic salts are, for example, chlorides, sulfates and nitrates. Organic salts are understood as meaning salts of carboxylic acids, for example formates, acetates and stearates. A prerequisite for this is in any case that the appropriate combination of inorganic or organic anion and metal cation exists. The person skilled in the art knows which of these combinations exist.

By spinning said solution of at least one polymer and at least one metal salt, polymer-containing fibers are first obtained. The at least one polymer can then be thermally, chemically, radiation-chemically, physically, biologically, with plasma, ultrasound or by

Remove extraction with a solvent. Preferably, the polymer is through

Pyrolysis in an oxygen-containing atmosphere (e.g., air). This gives metal oxide fibers.

These metal oxide fibers can then be reduced to metal fibers. Suitable reducing agents are, for example, hydrogen, carbon monoxide, gaseous hydrocarbons, carbon, furthermore metals having a more negative standard potential than the metal to be reduced, furthermore sodium borohydride, lithium aluminum hydride, alcohols and aldehydes. Alternatively, the metal oxide fibers can be reduced electrochemically.

In the case of composite filters according to the invention, in which the at least one nonwoven comprises electrospun metal or metal oxide fibers, the carrier material must be chosen such that it withstands the above-described production process of the electrospun fibers, in particular the removal of the polymer.

Suitable carrier materials consist for example of the abovementioned

Polymers, provided that these under the production conditions of the metal or metal oxide non-wovens are not degraded. Furthermore are

Support materials consisting of the above-mentioned mineral fibers and / or porous solids; as well as the mentioned plastic and membrane filters, provided that they survive the production process of the metal or metal oxide comprehensive webs. It is known to the person skilled in the art which carrier materials survive the above-mentioned production conditions for electrospun webs comprising metal or metal oxide. He can apply this knowledge without the

To leave the scope of the claims.

When the electrospun fibers are ceramic fibers, they consist of mixtures of alumina and silica, optionally with boron oxide and / or zinc oxide. The person skilled in the art is aware that such Fibers can be prepared, for example, by dissolved in water salts or colloidally dissolved inorganic components with organic polymers, such as polyvinyl alcohols or polyethylene oxides, mixed and spun. The so-called green fiber obtainable by this spinning process is converted by a sintering process into the corresponding oxide ceramic fiber.

Alternatively, the ceramic fibers may be silicon carbide fibers. It is known to the person skilled in the art that the preparation of such ceramic fibers takes place via polycarbosilanes as precursors.

It has been found that an application thickness of the fibers on the at least one support material of 0.1 g / m ² to 10.0 g / m ² gives particularly good filtration results in terms of filtration rate and filtration efficiency. This level of application is sufficient to quantitatively filter microorganisms from aqueous solutions, and the flow resistance of the composite filters is sufficiently low to allow a good filtration rate.

The ratio of nonwoven to substrate surface is preferably 0.3 g / m ² to 5.0 g / m ² . Most preferably, this ratio is 0.5 g / m ² to 2.0 g / m ² .

The diameter of the fibers is preferably 10 nm to 50 μm. Fiber diameters between 50 nm and 500 nm are particularly preferred.

In a further preferred embodiment, the at least one carrier material is paper, for example a porous paper made of cellulose, and the at least one nonwoven made of electrospun fibers is a nonwoven made of electrospun polymer fibers.

In a further preferred embodiment, the webs of electrospun fibers are gradient nonwovens. "Gradient" can affect the

Fiber diameter and / or refer to the polymers. For example, it may be a non-woven of a single polymer, wherein the

Fiber diameter has a gradient. Likewise, it may be nonwovens of at least two different polymers, wherein the proportion of the polymer varieties in wt .-% within the nonwoven and / or the diameter of the fibers of these different polymers varies. The electrospun webs naturally have pores, and the characteristics of the pores, for example, their size and shape, greatly affect the filtration properties of the composite filters of the present invention. The characteristic of these pores (or the porosity of the web) depends above all on the fiber diameter.

It is advantageous to keep the application thickness of the fibers on the carrier material low. The application thickness of two nonwovens can be the same, although the fiber diameters of both nonwovens are different. With the same application strength, the smaller the fiber diameter, the higher the filter efficiency.

The pore size of the electrospun nonwovens also depends on the fiber shape. According to the invention, the fibers may be smooth, rough, barbed nanowire fibers or structured, cylindrical, spindle-shaped or undulated, solid or hollow, and optionally may have thickenings. Barbed nanowire fibers are particularly advantageous for the filtration of bacteria, as bacteria adhere to these fibers very well.

In another embodiment, the electrospun webs have a web-like structure. "Tissue-like" here means that several nonwoven layers are superimposed, each layer lying at right angles to the layer above and below it, however, there is no crossover of the fibers, as is the case with "real" fabrics. In the case of fabric-like nonwovens, any number of layers can come to lie one above the other.

In another embodiment, the electrospun webs are made of functional polymers. These are understood to mean polymers which can chemically or biologically interact with microorganisms or polymers which are equipped with antibacterial substances.

An interaction of polymers with microorganisms is possible when the polymers carry certain functional groups which interact with the surface proteins of the microorganisms. Such groups are, for example, but not exhaustive, aldehyde groups. Antibacterial substances are, for example, antibiotics, quaternary nitrogen compounds but also metals and metal compounds such as titanium dioxide, zinc oxide and silver.

The support materials can be rough or smooth.

In a preferred embodiment, the composite filters according to the invention consist of a layer of a permeable, liquid-permeable carrier material and a layer of a fleece of electrospun fibers.

In a further embodiment, the composite filters according to the invention consist of several layers of carrier materials and electrospun fiber webs. In this case, both the carrier materials and the nonwovens can be identical or different independently of each other in each layer.

The composite filters according to the invention can be regenerated and cleaned very easily: it could be shown that the microorganisms only rest on the fleece, but not on the inside between the fibers. By irradiation with UV light or heating, the microorganisms can be killed. The prerequisite for this, of course, is that the fleece and the carrier material are UV- or temperature-stable.

Optionally, to filter bacteria, use composite filters containing the TiO ₂ particles as additives or add TiO ₂ particles to the composite used filter and then irradiate with UV light to increase the irradiation efficiency.

The use of antibiotic-containing composite filters or the subsequent addition of antibiotics and optional subsequent irradiation with UV light kill bacteria. It is known that antibiotics can act bacteriostatically, bactericidally or bacteriolytically. Bacteriostats only prevent bacteria from multiplying, but do not kill them. Bactericides kill bacteria, but do not destroy their cell wall, while bacteriolytics kill the bacteria and dissolve their cell wall. If the antibiotics in the antibiotic-containing composite filters according to the invention are bacteriostats, the killing of the bacteria takes place only by irradiation with UV light, while bactericides and bacteriolytics themselves kill the bacteria. Instead of bactericidal antibiotics can also other bactericidal substances are used, for example bactericidal quaternary nitrogen compounds.

If the microorganisms are killed by irradiation and the fleece is a polymer fiber fleece, then a UV or at least daylight-stable polymer must be used. As daylight also contains UV components, it is possible to optionally use daylight instead of pure UV light.

The composite filters according to the invention have excellent service lives, i. If the carrier material of the composite filter is made of paper, dry running of the filter should be avoided, since the electrospun web can then separate from the carrier material.As long as the composite filter is kept moist and a pressure difference is applied, the paper and nonwoven will be dissolved but not from each other.

It could be shown that the composite filters according to the invention are better suited for the separation of microorganisms from solutions contaminated therewith than filters consisting exclusively of electrospun nonwovens. This is shown, for example, in exemplary embodiment 2: A "pure" nonwoven material without a carrier material must be comparatively dense, otherwise it can not be handled mechanically The filtration quality of "pure" nonwovens is comparable to composite filters, but the filtration time is significantly higher in the first case.

The present invention provides means for separating microorganisms from contaminated liquids. Under microorganisms according to the invention

Archaea, bacteria, fungi, algae, protozoa and viruses understood. Algae and fungi can be both single-celled and multicellular. According to the invention, the term "microorganisms" in the case of algae and fungi refers to those protozoa and multicellular dressings whose maximum extent is less than or equal to 0.2 mm and thus just below the resolution of the human

Eye is lying.

Archaea are single-celled organisms with a mostly self-contained DNA molecule (also referred to as chromosome), which is arranged in a small volume and is referred to in this form as the core equivalent. So they belong to the prokaryotes and have neither a cytoskeleton nor cell organelles. Following are Phyla (strains), classes and orders of these archaea named according to their phylogenetic system:

- Phylum: Crenarchaeota - Class: Thermoprotei

Odor: Caldisphaerales

Family: Caldisphaeraceae Odor: Cenarchaeales

Family: Cenarchaeaceae - order Desulfurococcales

Family Desulfurococcaceae family Pyrodictiaceae order Sulfolobales

Family Sulfolobaceae - Order Thermoproteales

Family Thermoproteaceae family Thermofilaceae

- Phylum: Euryarchaeota

- Class Archaeoglobi - Order Archaeoglobales

Family Archaeoglobaceae

- Class Halobacteria

Order Halobacteriales - family Halobacteriaceae - class Methanobacteria

- Order Methanobacteriales

Family Methanobacteriaceae family Methanothermaceae

- Class Methanococci - Order Methanococcales

Family Methanocaldococcaceae family Methanococcaceae

- Class "Methanomicrobia"

Order Methanocellales Family Methanocellaceae

- Order Methanomicrobiales

Family Methanocorpusculaceae Family Methanomicrobiaceae - family Methanospirillaceae

- Order Methanosarcinales

Family Methanosaetaceae

- Family Methanosarcinaceae family Methermicoccaceae - genus Methanopyri

Order Methanopyrales family Methanopyraceae

- Class Thermococci

- Order Thermococcales - Family Thermococcaceae

- Class Thermoplasmata

- Order Thermoplasmatales

Family Ferroplasmataceae

- Family Picrophilaceae - Family Thermoplasmataceae

Bacteria in the sense of the present invention are microscopically small, mostly unicellular organisms which have no true cell nucleus and therefore belong to the prokaryotes. As with all prokaryotes, the DNA of bacteria is not contained in a cell nucleus bounded by a double membrane by the cytoplasm, as in eukaryotes, but the DNA lies freely in the cytoplasm, compressed in a narrow space, the nucleoid (nuclear equivalent).

With the aid of the composite filter according to the invention, bacteria can be separated from liquids. Following are phyla (strains), classes and orders of these bacteria according to the phylogenetic system of bacteria called:

- Phylum: Aquificae

- Class: Aquificae - Odor: Aquificales - Phylum: Thermotogae

- Class: Thermotogae

- Order: Thermotogales

- Phylum: Thermodesulfobacteria - Class: Thermodesulfobacteria

Order: Thermodesulfobacteriales

- phylum: Deionococcus-Thermus

- Class: Deinococci

Orders: Deionococcales, Thermales - Phylum: Chloroflexi

- Class: Chloroflexi

Orders: Chloroflexales, Herpetosiphonales

- Class: Anaerolineae

- Order: Anaerolineal - Phylum: Thermomicrobia

- Class: Thermomicrobia

Order: Thermomicrobiales

- Phylum: Nitrospira

- Class: Nitrospira - Order: Nitro spirals

- Phylum: Deferribacteres

- Class: Deferribacteres

Order: Deferribacterales

- Phylum: Cyanobacteria - Class: Cyanobacteria

Orders: Subsection I (formerly Chroococcales), Subsection II (Pleurocapsales), Subsection III (Oscillatoriales), Subsection IV (Nostocales), Subsection V (Stigonematales)

- Phylum: Chlorobi - Class: Chlorobia

- Order: Chlorobiales

- Phylum: Proteobacteria

- Class: Alphaproteobacteria - Orders: Rhodospirillales, Rickettsiales, Rhodobacterales, Sphingomonadales, Caulobacterales, Rhizobiales, Parvularculales

- Class: Betaproteobacteria

- Orders: Burkholderiales, Hydrogenophilales, Methylophilales, Neisseriales, Nitrosomonadales, Rhodocyclales, Procabacteriales

- Class: Gammaproteobacteria

- Orders: Chromatiales, Acidithiobacillales, Xanthomonadales, Cardiobacteriales, Thiotrichales, Legionellales, Methylococcales, Oceanospirillales, Pseudomonads, Alteromonadales, Vibrionales, Aeromonadales, Enterobacteriales, Pasteurellales

- Class: deltaproteobacteria

- Odnungen: Desulfurellales, Desulfovibrionales, Desulfobacterales, Desulfarcales, Desulfuromonales, Synthrophobacterales, Bdellovibrionales, Myxococcales (Suborders: Cystobacterieae, Sorangineae, Nannocystineae)

- Class: epsilonproteobacteria

- Order: Campylobacterales

- Phylum: Firmicutes

- Class: Clostridia - Orders: Clostridiales, Thermoanaerobacteriales, Haolanaerobiales

- Class: Mollicutes

- Orders: mycoplasmatales, entomoplasmatales, acholeplasmatales, anaeroplasmatales, incertae sedis

- Class: Bacilli - Orders: Bacillales, Lactobacillales

- Phylum: Actinobacteria

- Class: Actinobacteria

- Orders: Acidimicrobiales, Rubrobacterales, Coriobacteriales, Sphaerobacterales, Actinomycetales (Suborders: Micorcoccineae, Corynebacterineae, Actinomycineae, Propionibacterineae,

Pseudonocardineae, Streptomycineae, Streptomycineae,

Micromonosproineae, Frankineae, Glycomycineae), Bifidobacteriales

- Phylum: Planctomycetes

- Class: Planctomycetacia - Order: Planctomycetales - Phylum: Chlamidiae

- Class: Chlamydiae

- Order: Chlamydiales

- Phylum: Spirochaetes - Class: Spirochaetes

Order: Spirochaetales

Phylum: Fibrobacteres

- Class: Fibrobacteres

- Order: Fibrobacterales - Phylum: Acidobacteria

- Class: Acidobacteria

- Order: Acidobacteriales

- Phylum: Bacteroidetes

- Class: Bacteroidetes - Order: Bacteroidales

- Class: Flavobacteria

Order: Flavobacteriales

- Class: Sphingobacteria

- Order: Sphingobacteriales - Phylum: Fusobacteria

- Class: Fusobacteria

- Order: Fusobacteriales

- Phylum: Verrucomicrobia

- Class: Verrucomicrobiae - Order: Verrucomicrobiales

- Phylum: Dictyoglomi

- Class: Dictyoglomi

- Order: Dictyoglomales

- Phylum: Gemmatimonadetes - Class: Gemmatimonadetes

- Order: Gemmatimonadales

The bacteria which can be separated from liquids with the aid of the composite filters according to the invention include, for example, but not exhaustively Eschericia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Micrococcus luteus.

Viruses are intracellular, but not cellular, parasites in living cells. Viruses contain nucleic acids (DNA or RNA) for their proliferation and spread, but have no cytoplasm and therefore no metabolism of their own and are therefore dependent on the metabolism of the host cell. They are thus intracellular

Parasites. Viruses attack cells of eukaryotes (plants, animals, humans, fungi) and prokaryotes (bacteria and archaea). Viruses that use prokaryotes as hosts are called bacteriophages.

Viruses come in two forms:

as nucleic acid (DNA or RNA) in the cells of the host. The nucleic acid contains the information for its replication and for the reproduction of the second

Virus form (called virion). The host cell replicates the nucleic acid (proliferation).

- as virions, which are released to spread the virus from the host cells.

The classification of viruses is based on three criteria:

- enveloped and non-enveloped viruses,

- DNA or RNA genomes,

single stranded (ss) or double stranded (ds) nucleic acid.

In the context of the present invention, viruses are counted among the microorganisms. In the following, by way of example, but not exhaustively, some viruses are named whose hosts are bacteria, plants, animals and / or humans and which can be separated from liquids with the aid of the composite filters according to the invention:

bacteriophages:

Lambda, lambdoid phage, M13 phage, Mu phage, P1 phage, P22 phage, QD phage, T-even phage, T-odd phage, T2 phage, T4 phage, T7 phage. Plant viruses:

Alfalfa mosaic virus, Bromovirus, Capillovirus, Carlavirus, Carmovirus, Caulimovirus, Closterovirus, Cryptovirus, Cucumovirus, Dianthovirus, Fabavirus, Fijivirus, Furovirus, Geminivirus, Hordeivirus, llarvirus, Luteovirus, Machlovirus, Marafivirus, Necrovirus, Nepovirus, Phytoreovirus, Plant Rhabdovirus, Potexvirus , Sobovirus, Tenuivirus, Tobamovirus, Tobravirus, Tomato spotted wilt, Tombusvirus, Tymovirus.

Viruses infecting animals:

Adenovirus, Arenaviridae, Baculoviridae, Bimaviridae, Bunyaviridae, Caliciviridae, Cardioviruses, Coronaviridae, Corticoviridae, Cystoviridae, Epstein-Barr Virus, Enterovirus, Filoviridae, FMD Viruses, Hepadnaviridae, Hepatisviruses, Herpesviridae, Immunodeficiency Viruses, Influenza Virus, Inoviridae, Orthomyxoviridae, Papovaviruses, Paramyxoviridae, Parvoviridae, Picornaviridae, Polioviridae, Polydnaviridae, Poxviridae, Reoviridae, Retroviruses, Rhabdoviridae, Rhinoviruses, Semliki Forest Virus, Tetraviridae, Togaviridae, Toroviridae, Vaccinia Virus, Vesicular Stomatitis Virus.

Human pathogenic viruses:

Enveloped viruses: double-stranded DNA viruses (dsDNA)

- Family: Poxviridae

Subfamily: Chordopoxvirinae

Species: Orthopoxvirus, Parapoxvirus, Molluscipoxvirus - Family: Herpesviridae

Subfamily: Alphaherpesvirinae

Genera: simplex virus, varicellovirus

Subfamily: Betaherpesvirinae

- Genera: Cytomegalovirus, Reseolovirus - Subfamily: Gammaherpesvirinae

- Genera: Lymphocryptovirus, Rhadinovirus

- Family: Hepadnaviridae

- Genus: Orthohepadnavirus Enveloped viruses: single (+) - strand RNA viruses (ss (+) RNA)

- Family: Togaviridae

- Genera: Alphaviruses, Rubiviruses

- Family: Flaviviridae - Genera: Hepacivirus, Flavivirus

- Family: Coronaviridae

- Genera: coronavirus, torovirus

- Family: Retroviridae

Subfamily: Orthoretrovirinae genera: deltaretrovirus, lentivirus

Enveloped viruses: single (-) - strand RNA viruses (ss (-) RNA)

- Family: Arenaviridae

- Genus: Arenavirus - Family: Bornaviridae

- Genus: Bornavirus

- Family: Bunyaviridae

- Species: Orthobunyavirus, phlebovirus, nairovirus, hantavirus

- Family: Filoviridae - genera: Marburg virus, Ebola virus

- Family: Orthomyxoviridae

- genera: influenza virus A, influenza virus B, influenza virus C

- Family: Paramyxyviridae

Subfamily: Paramyxovirinae genera: Avulavirus, Morbillivirus, Henipavirus, Rubulavirus

Subfamily: Pneumovirinae

- genera: pneumovirus, metapneumovirus

- Family: Rhabdoviridae

Genera: Vesiculovirus, Lyssavirus

Non-enveloped viruses: double-stranded DNA viruses (dsDNA)

- Family: Adenoviridae

- Genus: Mastadenovirus

- Family: Polyomaviridae Genus: Polyomavirus

- Family: Papilllomaviridae

Genus: Papillomavirus - Subgenus: Human papillomaviruses

Non-enveloped viruses: single-stranded DNA viruses (ssDNA)

- Family: Parvoviridae

Subfamily: Parvovirinae

- Genera: Dependovirus, erythroid virus

Non-enveloped viruses: double-stranded RNA viruses (dsRNA)

- Family: Reoviridae

Genera: rotavirus, coltivirus

nested viruses: single (+) - strand RNA viruses (ss (+) RNA)

- Family: Caliciviridae

- Genera: norovirus, sapovirus

- Family: hepevirus

- Genus: Hepevirus - Family: Picomaviridae

- Genera: enterovirus, hepatovirus, rhinovirus

Algae, mostly aquatic, single to multicellular eukaryotic organisms, which are assigned to the plant kingdom, although some of their characteristics suggest a relationship to animals, and which in their entirety do not constitute a cohesive genealogy. Algae are divided into nine divisions: Glaucophyta, Euglenophyta, Cryptophyta, Chlorarachnophyta, Dinophyta, Haptophyta, Heterocontophyta, Rhodophyta and Chlorophyta. The skilled person is aware that in some of these departments there are both single-celled algae and multicellular to those which form tissue-like cell aggregates.

Fungi are eukaryotic organisms whose cells contain mitochondria and a cytoskeleton. In the biological classification they form apart from animals and plants an independent kingdom, which includes single-celled organisms as well as baker's yeast as well as multicellular organisms such as molds and edible mushrooms. Numerous monocellular and multicellular Fungi are relevant to plants, animals and humans: some are pathogenic, others are medically significant, biotechnologically relevant, or they cause mold.

Hereinafter, by way of example, but not exhaustively, some fungi are mentioned which can be separated from liquids with the aid of the composite filters according to the invention.

The fungi which cause mycoses (fungal diseases) in plants include, for example, Erysiphales (powdery mildew fungi), Peronosporaceae (false downy mildew), Claviceps purpurea (ergot), Diplocarpon rosae (star sooty), Phytophtora infestestans (cabbage rot), Ophiostoma novo -ulmi, Ophiostoma ulmi, synonym: Ceratocystis υlmi (elm dying), Ustilago maydis (corn dew), Tilletia caries, synonymous: Tilletia tritici (stone fire in wheat), Vθrticillum (wilting disease in many crops), Venturia (apple scab), Gymnosporangium sabinae (pear grid ), Nectria galligena (fruit tree crayfish), Taphrina pruni (fool's disease), as well as the brown rot, caused for example by the Lärchenporling (Laricifomes officinalis), the Schwefelporling {Laetiporus sulphureus) or the Bitteren Saftporling {Spongiporus stipticus) and the white rot, caused for example by Trameten (Trametes and Daedolopsis), the fire sponges (Phellinus) , Tinder sponges (Fomes), House Porfolus (Donkioporia expansa, also called "Oak Porling"), Butterfly Porcupine (Trametes versicolor, Butterfly Tramete), and most wood-lobed (Xylariaceae).

In addition to numerous other types of fungi, the spongy damage caused by brown rot in buildings is especially true of the dry rot (Serpula lacrymans), the brown cellar sponge {Coniophora puteana) and the white pore sponge (Antrodia vailantii or Antrodia sinuosa).

Fungi include fungi of the genera Acremonium, Alternaria, Aspergillus, Aureobasidium, Botrytis, Chaetomium, Cladosporium, Claviceps, Curvularia, Dematiaceae, Eurotium, Fusarium, Monilia, Mucor, Mycelia sterilia, Neurospora, Paecilomyces, Penicillium, Phoma, Rhizopus, Scopulariopsis, Stachybotrys, Stemphylium, Trichoderma, Ulocladium, Wallemia. Furthermore, there are some fungi that cause mycoses as parasites in living tissue. The pathogens of mycoses are differentiated into dermatophytes (filamentous fungi), yeasts (yeasts) and molds (see above). Currently, 38 types of dermatophytes are known to be pathogenic in humans and / or animals. They belong to the three genera Microsporum, Trichophyton and Epidermophytum within the family Moniliaceae. A yeast pathogenic to humans and many animals is Candida albicans.

On the other hand, many yeasts are economically important, such as the food industry. These include, for example, but not exhaustive

Schizosaccharomyces pombe, Saccharomyces cerevisiae, Saccharomyces carlshergensis, Saccharomyces uvarum, Candida utilis, Saccharomyces boulardii,

Pichia pistoris and Brettanomyces bruxellensis, the latter on the one hand for

Must and wine is a pest yeast, on the other hand, but also used for beer production.

In addition, yeasts such as e.g. Arxula adeninivorans (Blastobotrys adeninivorans), Candida boidinii, Hansenula polymorpha {Pichia angusta), Kluyveromyces lactis, Pichia pastoris, Saccharomyces cerevisiae and Yarrowia lipolytica use as expression platforms.

Fungi that can be separated from liquids using the composite filters of the present invention include, but are not limited to, Aspergillus niger and Chaetomium globosum.

Protozoa are unicellular organisms that do not have a cell membrane but, unlike bacteria, have a true cell nucleus. A so-called true cell nucleus is delimited from the cytoplasm by a double membrane called the nuclear envelope or nuclear membrane. The presence of a true cell nucleus is the characteristic feature of eukaryotes, which is why protozoa are among the eukaryotes.

With the aid of the composite filter according to the invention, protozoa can be separated from liquids. The following are classes and orders of protozoa according to the zoological classification: - 1st class: Flagellata (flagellum, whip-lizard)

- 1st order: Choanoflagellata

- 2nd order: Trichonomonadida

- 3rd order: Diplomonadida - 4th order: Hypermastigida

- 5th order: Kinetoplastida

- 6th order: Opalinida

- 2nd class: Rhizopoda (root feeder) - 1st order: Amoebina (feeder)

- 2nd order: Testacea (Theca)

- 3rd order: foraminifera

- 4th order: Radiolaria (radiolarians)

- 5th order: Heliozoa (Sonnentierchen)

- 3rd class: Sporozoa (Sporiertierchen)

- 1st order: Gregarinida

- 2nd order: coccidia

- 3rd order: Piroplasmida

- 4th grade: Microspora

- 5th grade: Myxozoa

- 6th grade: Ciliata (crayfish)

- 1st order: Holotricha

- 2nd order: Petritricha

- 3rd order: Spirotricha

- 4th order: Chonotricha - 5th order: Suctoria

Preference is given to protozoa which can be separated from liquids with the aid of the composite filters according to the invention, for example, but not exhaustively, Plasmodium falciparum, Plasmodium ovale, Plasmodium vivax and Plasmodium malaήae. The composite filters according to the invention comprising at least one permeable, liquid-permeable carrier material and at least one fleece made from electrospun fibers are produced by applying the at least one carrier material to the counterelectrode 7 of an electrospinning apparatus (as shown in FIG. 1) and depositing at least one nonwoven thereon by means of the electrospinning process becomes. The material to be spun does not necessarily have to touch the counterelectrode. Alternatively, the material to be spun can also be guided over the electrode surface without contact in a continuous process.

The polymer or polymers from which the at least one nonwoven fabric is to be produced are dissolved in at least one solvent prior to electrospinning. By "soluble" is meant that the polymer or polymers have a solubility of at least 1 wt .-% in the corresponding solvent.

The person skilled in the art knows which polymers are soluble in which solvent or solvent mixture as defined above. He can apply this knowledge without departing from the scope of the claims.

Suitable solvents are, for example, but not exhaustive:

Water, aliphatic alcohols, for example methanol, ethanol, n-propanol, 2-propanol, n-butanol, isobutanol, tert-butanol, cyclohexanol, carboxylic acids which are liquid at room temperature, for example formic acid, acetic acid, trifluoroacetic acid

Amines, for example diethylamine, diisopropylamine, phenylethylamine, polar aprotic solvents, for example acetone, acetylacetone, acetonitrile, ethyl acetate, diethylene glycol, formamide, dimethylformamide (DMF),

Dimethylsulfoxide (DMSO), dimethylacetamide, N-methylpyrrolidone (NMP), pyridine, benzyl alcohol, halogenated hydrocarbons, for example dichloromethane, chloroform, nonpolar aliphatic solvents, for example alkanes, selected from hexane, heptane, octane and cycloalkanes selected from cyclopentane, cyclohexane, cycloheptane, nonpolar aromatic solvents, for example benzene, toluene.

In this case, water is suitable as a solvent, especially for the production of electrospun metal or metal oxide.

Advantageously, such solutions are spun, the polymer content is 1 wt .-% to 25 wt .-%.

The polymer solution to be used according to the invention can be electrospun in all manners known to the person skilled in the art, for example by extrusion of the solution under low pressure through a cannula connected to one pole of a voltage source on a counter electrode arranged at a distance from the cannula outlet. On this counter electrode is the at least one carrier material.

Preferably, the distance between the cannula and the counterelectrode acting as collector and the voltage between the electrodes is set such that between the electrodes an electric field of preferably 0.5 to 2 kV / cm. The result is a flow of material directed at the counterelectrode, which solidifies on the way to the counterelectrode.

Good results are obtained, in particular, when the diameter of the cannula is 50 μm to 500 μm.

The person skilled in the art knows how to adjust the fiber diameter. Thus, for example, the fiber diameter becomes greater, the more viscous, ie the more concentrated the polymer solution to be spun. The higher the flow rate of the spinning solution per unit time, the larger the diameter of the obtained electrospun fibers. Furthermore, the fiber diameter depends on the surface tension and the conductivity of the spinning solution. This is known to the person skilled in the art and he can apply this knowledge without departing from the scope of the patent claims. The application thickness of the fibers on the carrier material (in g / m ² ) is preferably kept low. The more concentrated the spinning solution is, the higher the application strength per time. As already stated, the application thickness can be the same for different fiber diameters, and the fiber diameter depends on the characteristics of the pores in the nonwoven fabric.

According to the invention, the fibers can be smooth, rough, barbed wire (so-called Barbed nanowire fibers) or structured, cylindrical, spindle-shaped or undulating, solid or hollow, and they can optionally have thickenings. It is known to those skilled in the art how to make such fibers by, for example, varying the concentration of the spinning solution, the application level and the applied voltage. For example, the spinning of relatively dilute aqueous polymer solutions with a maximum of about 5 weight percent polymer at relatively high voltages results in Barbed nanowire fibers. Bi- and polymodal fiber diameters are obtained when multiple polymer solutions are spun simultaneously in at least two different reservoir vessels equipped with capillary jets. With the aid of this last-mentioned process variant, the porosity of the webs obtained can be controlled particularly advantageously, for example by increasing the proportion of fine fibers and reducing the proportion of coarse fibers.

Hollow fibers can be produced by first producing a massive fiber from a degradable polymer. Subsequently, this fiber is coated with a second, non-degradable material. This may be, for example, a non-degradable polymer, a metal, a metal salt or a ceramic material. Optionally, multiple layers of the same or different non-degradable materials can be applied. Subsequently, the first massive fiber is removed, e.g. thermally, by irradiation or with a solvent. What remains is a hollow fiber, the inner wall of the second, non-degradable material and the outer wall of the last applied non-degradable material.

In another embodiment, the electrospun webs have a web-like structure as described above. Such fabric-like nonwovens are produced by a special spinning technique: In the production of the first layer of the nonwoven fabric, the counterelectrode (ie the "base" on which the fibers are deposited) has an orientation x. Subsequently, the counterelectrode becomes in-plane Turned 90 ° and spun the second layer. The first and the second layer of the web are then at right angles to each other. This rotation of the counter electrode can be repeated as often as desired, and the rotation angle can optionally also deviate from 90 °, wherein the layers are shifted in the latter case against each other, but not come to lie at right angles.

Nonwovens of functional polymers are obtainable by spinning polymers containing appropriate functional groups, for example aldehyde groups. With a suitable choice of the functional polymer, either surface proteins of the microorganisms can be bound to the nonwoven or also antibiotic molecules.

Furthermore, polymer fleeces can be equipped with antibacterial substances. These include, for example, particles of antibacterial metals and metal compounds, such as titanium dioxide, zinc oxide and / or silver. In addition, antibacterial non-metallic substances such. As quaternary nitrogen compounds and particles of these substances are introduced into the polymer webs.

Water soluble fibers are chemically linked or crosslinked with each other after the electrospinning process as described above.

All of the polymers mentioned above can be spun. Furthermore, all the above-mentioned carrier materials can be used.

The production of gradient nonwovens according to the above definition is known from the literature.

The composite filters according to the invention can be used for the separation of microorganisms from liquids contaminated therewith. The microorganisms are selected according to the above definition from bacteria, viruses, fungi, protozoa, algae and viruses, where algae and viruses are unicellular or multicellular associations, the largest dimension is less than or equal to 0.2 mm.

The filtration can be operated continuously or discontinuously. The above-described regeneration of the filters can also be carried out during a continuous filtration. The separation of microorganisms from contaminated liquids with the aid of the composite filter according to the invention is expediently carried out with a pressure difference. This can be either an overpressure filtration or a vacuum filtration.

The microorganisms contaminated liquids may be industrial or domestic effluents and service waters (for example from sewage treatment plants and swimming pools), microbiological fluids containing microorganisms and medicines such as cell culture media containing these microorganisms, blood plasma or blood serum. Furthermore, these contaminated fluids may be coolants. For example, water-miscible cooling lubricants are often attacked by bacteria. Often, therefore, preservatives are added, which, however, can cause skin irritation. The cleaning of contaminated cooling lubricants using the composite filter according to the invention offers a remedy here. It is also possible to separate off microorganisms from aqueous solutions of water-miscible organic solvents and from emulsions. The prerequisite for this is that the electrospun nonwoven fabric of the composite filter according to the invention consists of an oil-stable material. It is known to the person skilled in the art that metal fibers, metal oxide fibers, carbon fibers and ceramic fibers are oil-stable. He is also aware of which polymer fibers are oil stable. These include, for example but not exhaustively, fibers of polyamide, polyvinyl chloride and polystyrene.

In a preferred embodiment, the composite filters according to the invention are used for the separation of bacteria from liquids contaminated therewith.

A further embodiment of the invention provides for the use of a means for separating microorganisms from contaminated liquids in a filter, wherein the means is a composite filter comprising at least one permeable, liquid-permeable carrier material and at least one nonwoven made of electrospun fibers.

The carrier material may be a fiber-oriented nonwoven, a random fiber web, a porous solid, a woven fabric, a paper filter, a plastic filter, a metal sieve or a membrane filter. The fibers may be water-stable polymer fibers, metal fibers, metal oxide fibers, carbon fibers or ceramic fibers. A particularly advantageous application provides that the filter is a refrigerator filter or a sub-rinse filter.

LIST OF REFERENCE NUMBERS

1 voltage source

2 capillary nozzle

3 syringe

4 spinning solution

5 counter electrode

6 fiber formation

7 fiber fleece

Figure legends

Fiq. 1

1 shows a schematic representation of a device suitable for carrying out the electrospinning process according to the invention.

The device comprises a syringe 3, at the tip of which is a capillary nozzle 2. This capillary nozzle 2 is connected to a pole of a voltage source 1. The syringe 3 receives the polymer solutions 4 to be spun. Opposite the outlet of the capillary nozzle 2, a counterelectrode 5 connected to the other pole of the voltage source 1 is arranged at a distance of about 20 cm, which acts as a collector for the fibers formed.

During operation of the device, a voltage of between 15 kV and 150 kV is set at the electrodes 2 and 5, and the polymer solution 4 is exposed to a small amount

Pressure through the capillary 2 of the syringe 3 discharged. Due to the electrostatic charge of the polymers in the solution due to the strong electric field of 0.5 to 2 kV / cm, an on the

Counter electrode 5 directed material flow, which solidifies on the way to the counter electrode 5 with fiber formation 6, as a result of which on the Gegenelekrode 5 fibers 7 with diameters in the micro and nanometer range.

Fig. 2 Polyamide 6 was spun from solutions in formic acid. Commercial paper filters equipped with layers of variable thickness were prepared. The filter paper with a diameter of 28 mm was placed on the collector electrode of the apparatus and spun at different times.

Solutions were used with a concentration between 10 and 19 wt .-%. To make the polyamide-6 filter fleece, a sterile piece of paper was placed on the collector electrode and spun. To remove the web, a cut piece of the spun paper was placed in sterile, demineralized water. After separation from the paper, the web was removed, dried under sterile conditions and stored in a sterile disposable petri dish.

The determination of the filter efficiency was carried out as described in Example 1 with a suspension of M. luteus.

Fig. 2 shows the plot of the Lebendzellzahl against the spinning time. For the filtration composite filter according to the invention were used.

Fig. 3

Tap water was, as described in Example 2a), pressed through a round filter, which was coated with polyamide 6-Fasem. Subsequently, the filter was examined under the scanning electron microscope.

Fig. 3 shows a scanning electron micrograph of the filter: On the left is the left on the filter pad, the right figure shows a point at which the pad was chipped.

The white bar at the bottom of the picture corresponds to a length of 2.00 μm (left) or 3.75 μm (right). Fig. 4

Tap water was, as described in embodiment 2a), pressed through a round filter, which was coated with nylon-6 fibers. Subsequently, the filter was examined under the scanning electron microscope.

4 shows a scanning electron micrograph of the filter: On the left is the transition between the fibers located beneath the filter apparatus and the coating. The right image shows fibers that were under the edge of the filter apparatus.

The white bar at the bottom of the picture corresponds to a length of 15.00 μm (left) or 2.00 μm (right).

Fig. 5 30 ml of E. coli suspension were drawn through the filter under reduced pressure and the filter cake was then rinsed off again with water. This is described in detail in embodiment 2b).

The left image of Fig. 3 shows an overview after rinsing, the right a detail. Remains of the filter cake can be seen; the fibers seem undamaged.

The white bar at the bottom of the picture corresponds to a length of 6.00 μm (left) or 2.00 μm (right).

embodiments

Exemplary Embodiment 1 Production of Bacterial Filters by Electrospinning

Micrococcus (M.) luteus was cultured at pH = 7 in a mixture of 5.0 g of meat extract and 3.0 g of peptone as the basis of the bacterial suspensions used to examine the filter efficiency. The bacteria were sedimented, washed and resuspended in 50 mM phosphate buffer pH = 7. To prepare the fibers, an apparatus was used as described in M. Bognitzki et al. Adv. Mater. 12, 637 (2000).

Polyamide 6 was spun from solutions in formic acid. Produced were commercial paper filters finished with layers of variable thickness and non-carrier supported filter webs. The paper filters were cellulosic filters with pores. The edition consisting of the electrospun fleece, but not the paper filter, was varied. To prepare the modified paper filters, the filter papers were dried to constant weight before use and sterilized at 130 ^° C. for three hours in a sterilizer. The electrospinning apparatus was cleaned with 70 vol% ethanol in water before the beginning of the spinning process and made germ-free as far as possible. The filter paper with a diameter of 28 mm was placed on the collector electrode of the apparatus and spun for different times.

Solutions were used with a concentration between 10 and 19 wt.%.

The distance between the electrodes was 20.0 cm and the voltage 25 kV. The flow rate was 0.2 mL / h. The coated paper filter was then removed from the electrode with a scalpel and stored in a sterile disposable petri dish until further use.

To make the polyamide 6 filter fleece, a sterile piece of paper was placed on the collector electrode and spun. To remove the web, a cut piece of the spun paper was placed in sterile, demineralized water. After separation from the paper, the web was removed, dried under sterile conditions and stored in a sterile disposable petri dish.

The efficiency of the filter media was determined by passing through the filter 40 mL of a suspension of M. luteus, with a viable cell count in the range of one million cells per milliliter of suspension. After filtering, the number of live M. luteus in the filtrate and analogously in the original suspension was determined by the KBE method (colony-forming units). For this purpose, the filtrate 0.1 mL was removed and a dilution series using 50 mmol / L phosphate buffer prepared at pH = 7. Subsequently, 0.1 ml of the various dilutions and of the filtrate were applied to agar plates and this incubated at 37 ⁰ C for 72 h. From the number of growing colonies, the number of living bacteria present in the sample was calculated. This is shown in FIG. 2.

Embodiment 2: Filter life

a) test the service life of the filters

The "life" is the life of the filter.

Approximately 10 L of tap water were pressed within ten hours with the aid of the line pressure through a round filter, which was covered with polyamide 6 fibers. The active filter area here was about 3.1 cm ^2. The amount of nylon-6 on the filter paper was 0.12 mg / cm ² . Subsequently, the filter was examined under the scanning electron microscope.

It turned out that the filter was completely covered with dirt, which had been filtered out of the water. At a point where the dirt layer had chipped off, it was clear that the underlying fibers were in good condition. The filters are shown in FIGS. 3 and 4.

b) Removal of the filter cake

30 mL of E. coli suspension at an approximate concentration of 4 * 10 ⁹ bacteria per mL were drawn through the filter with negative pressure. The filter cake was then rinsed with distilled water from a squeeze bottle, directing the stream of water directly at the filter. The filter cake could be removed except for a slight discoloration. Subsequently, the filter was examined by scanning electron microscopy.

It turned out that the filter cake did not completely peel off, but that the fibers had no obvious damage either.

The scanning electron micrographs are shown in FIG. 5. Embodiment 3

Comparison of a filter paper coated with PA 6 with a pure PA 6 membrane

A filter paper coated with PA 6 and a PA 6 membrane without supporting tissue were compared with regard to the filter effect and the throughput time of the medium to be filtered. For this purpose, in each case 30 ml of a bacterial suspension in sterile buffer solution having a bacterial concentration of about 1 × 10 ^{8 were} drawn through the filter to be tested by negative pressure.

Subsequently, the exact concentration of the bacteria in the original suspension as well as in the filtrate was determined. This was done by preparing a dilution series, applying a defined amount to an agar plate and then incubating. In this case, single bacteria showed up as colonies (CFU method). The efficiency of the filter is calculated according to the following equation:

C ₁ - C ₂

V =

C ₁

Here, η is the efficiency of the filter. C ₁ and C ₂ indicate the concentration of bacteria before and after filtration.

In both cases, the bacteria were virtually quantitatively removed from the buffer solution. However, the time taken for the 30 mL to pass through the filter was significantly longer at 19 minutes for the membrane without support material. On the other hand, with the filter paper coated with PA 6, the time was only 3.5 min. This is shown in Tab. 1.

Table 1: Comparative data of the two filters tested. Sample PA 6 per cm ² flow time efficiency

Pure PA 6 membrane 0.68 mg 19 min 1

Filter paper with PA 6 0.068 mg 3.5 min 1

The membrane of pure PA 6 thus requires a significantly longer time to filter 30 mL of bacterial suspension than the PA 6 occupied filter paper with the same filtration performance. It should also be noted that the PA 6 membrane with a basis weight of 0.68 mg per cm ² was practically no longer to handle due to the extreme instability. Thicker and therefore stiffer membranes would increase the filtration time even more drastically.

Claims

Patnetansprüche

1. A means for separating microorganisms from contaminated liquids, characterized in that it is composite filter comprising at least one permeable, liquid-permeable carrier material and at least one web of electrospun fibers.

2. A means for separating microorganisms from contaminated liquids according to claim 1, characterized in that as

Carrier material to be used filters are selected from fiber-oriented nonwovens, random fiber webs, porous solids, tissues, paper filters, plastic filters, metal screens and membrane filters.

3. A means for separating microorganisms from contaminated liquids according to claim 1 or 2, characterized in that the fibers are selected from water-stable polymer fibers, metal fibers, metal oxide fibers, carbon fibers, ceramic fibers.

4. means for separating microorganisms from contaminated liquids according to one of claims 1 to 3, characterized in that the application strength of the fibers on the at least one carrier material is 0.1 g / m ² to 10.0 g / m ² .

5. A means for separating microorganisms from contaminated liquids according to any one of claims 1 to 4, characterized in that the at least one carrier paper and the at least one web consists of electrospun fibers.

6. A means for separating microorganisms from contaminated liquids according to one of claims 1 to 5, characterized in that the nonwoven consists of electrospun polymer fibers.

7. A process for the production of composite filters according to one of claims 1 to 6, characterized in that the at least one carrier material is applied to the counter electrode of an electrospinning apparatus and the at least one nonwoven is deposited thereon by means of the electrospinning process.

8. Use of composite filters according to any one of claims 1 to 6 for the separation of microorganisms from contaminated liquids, wherein the microorganisms are selected from archaea, bacteria, viruses, fungi, protozoa, algae and viruses, wherein algae and viruses are protozoa or multicellular associations whose maximum dimension is less than or equal to 0.2 mm.

9. Use of composite filters according to claim 8, characterized in that the microorganisms are bacteria.

Use of an agent for separating microorganisms from contaminated liquids according to any one of claims 1 to 6 for use in a filter.

11. Use according to claim 10, characterized in that the filter is a refrigerator filter or a Unterspülenfilter.