DE19813870A1 - Non-immobilized bio-electrode detector - Google Patents

Abstract

The detector makes a quantitative determination of the presence of specific organic substances. The detection and measurement process takes place in a small reaction chamber with a sensor in a solution under a membrane and incorporating a mixer. The organic substance is diffused into the chamber via the membrane. The enclosed reaction chamber has a closure which may be opened as required for the replenishment of the solution.

Description

The invention relates to a device according to the preamble of claim 1.

So-called bioelectrodes are required to quantitatively record organic substances.

Bioelectrodes consist of a chemical-specific receiver on a biochemical basis, the Receptor, for the detection of the organic molecules to be detected and a transducer that the serves electrical transformation. Organic substances such as enzymes come as receptors, Microorganisms, organelles, antibodies, lectins, hormones, etc. are used. Serve as a transducer pH electrodes, gas electrodes or ion-selective electrodes. The receptor reacts specifically the substance to be quantified. The amount of the resulting reaction products is captured by the transducer and converted into an electrical variable. This allows the one to be recorded organic matter can be measured quantitatively.

The substance to be detected in the test solution and transducer of the bioelectrode are through separate the membrane layer (s) of the bioelectrode in which the receptors are firmly embedded (immobilized bioelectrode). The molecules of the substance to be detected diffuse into the membrane and react there with the receptor, the amount of reaction products created converted into an electrical quantity by the transducer. The receptor molecules can be aground their size does not diffuse through the pores of the membrane and are therefore in the membrane or immobilized between two membrane layers (depending on the arrangement).

Because the receptor is immobilized, there are several disadvantages:

• - When immobilized in the membrane, the amount of receptor molecules stored is not exactly known.
• - The immobilization reaction sometimes makes the sensitive Receptor molecules inhibited, blocked or destroyed.
• - Because a relatively thick membrane is used or the receptor between two Membranes are permanently installed because of a certain inertia of the bioelectrode the time it takes for the substrate molecules to pass through the membrane layer (s) diffuse.
• - The reaction of the receptor molecules with the substrate molecules is determined by the restricted movement of the receptor molecules impaired.
• - Only through a problematic and difficult and therefore unprofitable exchange of the This is the receptor where the old has to be removed and a new one has to be immobilized Increase the sensitivity of the bioelectrode, the renewal when the receptor is used up or switching to the evidence of another organic substance possible.

The object of the invention is organic substances as well as immobilized To be able to quantify bioelectrodes, the disadvantages of immobilized Fix bioelectrodes, however.

This object is achieved by a device with the features of claim 1.

If the receptor molecules are not, as with the immobilized bioelectrode in one Membrane or between two membranes but creates a small one Reaction space, i.e. a small bioreactor in which the receptors are in solution, it succeeds in overcoming the disadvantages of the design of the immobilized bioelectrode overcome.

The substrate molecules reach the reaction chamber through a membrane non-immobilized bioelectrode and which prevents the receptor from coming out  non-immobilized bioelectrode diffuses. However, this membrane can be much thinner fail as the membrane of the immobilized bioelectrode or is only a membrane here necessary. This results in a lower inertia of the bioelectrode, since the Substrate molecules do not have to cross such a thick membrane layer.

Compared to the immobilized bioelectrodes, when casting the membrane surplus or non-immobilized arise with the embedded receptors Rinsing out receptor molecules is exactly the case with the non-immobilized bioelectrode Amount of receptor known since all receptor molecules are in the solution.

The receptor is not inhibited, blocked or destroyed because there is no immobilization step of the receptor takes place.

The substrate can react freely with the receptor, since the receptor moves in the Reaction space of the non-immobilized bioelectrode is not restricted.

The receptor solution can be exchanged very easily and thus the sensitivity the bioelectrode is increased by a stronger or weaker concentrated receptor solution or reduced, the bioelectrode can simply be replaced when the receptor is used up become or easily on the detection of another organic substance by using a other receptor solution.  

Embodiments of the invention are shown in the drawing and are described in more detail below described.

The figure shows a cross section through the bioelectrode.

The non-immobilized bioelectrode essentially consists of a tube (2 cm in diameter) made of aluminum or plastic, into which the receptor solution can easily be filled from above. The tube is tightly closed at the lower end with a precisely fitting plate that is sealed with silicone adhesive. Just above this end there are 24 holes with a diameter of 5 mm each in 3 rows in the pipe. These rows of holes are covered with the membrane (also sealed with silicone adhesive or the like), it being possible to use different types of membranes (glass membrane, dialysis membrane,...). This results in a membrane surface of 4.7 cm ² capable of diffusion. The transducer in the form of a pH electrode, gas electrodes, ion-selective electrode or conductometer electrode is firmly locked in the tube. The volume of the receptor solution and the immersion depth of the transducer are ideally chosen so that the top row of holes and the sensitive area of the transducer are just in the solution. There is a magnetic piece at the bottom of the tube so that, together with a magnetic stirrer, an even distribution of the substrate and thus a uniform reaction are ensured.

In an embodiment that is not shown, the bioelectrode is inserted into the bioelectrode instead of the magnetic stirring device built-in rod stirrer used. In an embodiment, also not shown, is the membrane attached to the bottom of the tube. In a further embodiment, not shown, a much larger membrane and a much larger volume of the receptor solution used. In a further embodiment, not shown, the bioelectrode is firmly closed, the Exchange of the receptor solution through a closable opening instead finds.

Claims (3)

1. Device for the quantitative detection of specific organic substances, characterized in that the measurement takes place in a small reaction space in which the substance to be detected diffuses in via a membrane and in which the receptor is in solution. 2. Device according to claim 1, characterized in that there is a stirring device in the reaction chamber. 3. Device according to claim 1 or 2, characterized in that the reaction space is complete and the exchange of Receptor solution takes place through a tightly closable opening.