HU218903B - Biocompatible ionselective electrode - Google Patents

Abstract

The sensor (2) of a biocompatible ion selective electrode is constructed of 10-80 wt.% of polyurethane. This contains PVC and PVC complete with carboxy and/or hydroxy groups. The sensor contains active matter (e.g. a complexing compound) either in a molecular dispersion form or applied from its solution. Optionally, plasticiser and additives are also present the sensor (2), and a supporting phase, preferably netting, containing surface dispersed active matter or being impregnated by a solution of active matter.

Description

BACKGROUND OF THE INVENTION The present invention relates to a biocompatible ion-selective electrode for determining ion concentration, the sensing element of which is an aliphatic polyurethane containing an active substance and a mixture of polyvinyl chloride and polyvinyl chloride having special functional groups.

The rapid and accurate determination of the concentration of various ions present in body fluids, such as potassium and sodium, is of diagnostic importance. Selective in vitro and in vivo determinations of the concentration of various ions can be achieved most rapidly and conveniently using ion-selective electrodes potentiometrically.

The membrane sensing element of the ion selective electrode contains an active substance (e.g., a complexing compound, a precipitate) which is capable of electrochemically equilibrating with the ion to be determined in the sample. As a result of this equilibrium, the potential of the sensor contacting the sample is dependent on the concentration (activity) of the ion to be measured. The cell voltage of an electrochemical measuring cell consisting of an ion-selective electrode and a constant-potential reference electrode therefore carries quantitative information: its desired magnitude (activity) can be calculated (can be directly displayed by a suitable device).

Among the electrode constructions described in the literature (J. Havas: New Results in Chemistry, Volume 48: Ion and Molecular Selective Electrodes in Biological Systems. Akadémiai Kiadó, Budapest, 1980), the sensing element of a plastic material containing a heterogeneous distribution of the solid active substance polyvinyl chloride] membrane. The membrane-shaped sensing element is attached to the end of a so-called electrode body by a rigid polyvinyl chloride tube, also with a solution of polyvinyl chloride as an adhesive. The electrode body contains an electrolyte solution, which contacts the electrode body surface of the sensor element. A so-called internal reference electrode is immersed in the electrolyte solution.

One disadvantage of polyvinyl chloride-based membranes is the reduction of the so-called matrix effect (non-selective electrode function in the case of non-active membranes), which is described in Hungarian Patent No. 199,994B. However, the silicone rubber-containing, polyvinyl chloride-based sensor element of the present invention is pressure sensitive, highly vulnerable, and reliably adhesive to a polyvinyl chloride electrode body. These disadvantages significantly limit the life of the electrodes of the invention.

Another disadvantage of the known polyvinyl chloride-based membranes is that they form a poorly adherent layer on a solid surface and are therefore unsuitable for producing so-called solid-conducting, disposable sensor plates.

A further disadvantage is that they are not biocompatible and adsorb proteins on their surface in contact with biological fluids (such as blood). The variable surface protein layer degrades the sensitivity, reproducibility and lifetime of the electrode.

The object of the present invention is to provide an electrode structure which eliminates the described disadvantages (protein sensitivity, lack of biocompatibility), can be reliably adhered to the electrode body by gluing, and forms a good adhesive layer on a solid surface.

The present invention is based on the discovery that the disadvantages described above can be practically completely eliminated by forming the sensor element as a carrier from a biocompatible aliphatic polyurethane with a special functional group or groups forming an adherent layer through its functional groups (e.g. - Contains polyvinyl chloride having COOH, -OH) and polyvinyl chloride having adhesive properties.

BACKGROUND OF THE INVENTION The present invention relates to a biocompatible ion-selective electrode, preferably having a disc-shaped (membrane) sensing element made of polyurethane containing 10-80% by weight of a special functional group polyvinyl chloride and polyvinyl chloride, and the carrier phase having a molecular distribution of active or an active ingredient in a solvent, optionally known plasticizers and anionic suppressants.

The electrode of the present invention may also be configured such that the sensing member comprises a support phase (e.g., a mesh) treated with a solution of the known active material (e.g., swollen).

The biocompatible ion-selective electrode of the present invention is shown schematically in sectional view in accordance with one embodiment.

In Figure 1, a disc-shaped sensor element 2 is attached to one end of a tubular polyvinyl chloride electrode body 1. Inside the electrode body 1 is a 0.1 mol / l potassium chloride electrolyte solution 3, into which a silver / silver chloride secondary electrode is immersed as a potential conductor 4. The other end of the electrode body 1 is enclosed by a polyvinyl chloride insulating element 5 including a potential drain 4. Composition of the 2 sensing elements: 1.06 g polyurethane, 0.1 g carboxylated polyvinyl chloride, 0.16 g polyvinyl chloride, 0.10 g valinomycin active ingredient, 2.70 g bis (2- ethylhexyl) sebacate softener, 0.02 g potassium tetrakis (4-chlorophenyl) borate additive.

The disc-shaped sensor element 2 is formed by molding in a known manner by dissolving the sensor component components in a tetrahydrofuran solvent (14 g in an exemplary amount) and evaporating the solvent at room temperature. The sensor element 2 and the insulator element 5 are fixed with a solution of polyvinyl chloride in tetrahydrofuran as an adhesive to the end of the polyvinyl chloride electrode body.

The advantages of the electrode according to the invention over the known ones are as follows:

(a) Biocompatible (leukocyte count determined after 14 days in the case of a rat implanted detector in the abdomen) measured in the polyvinyl chloride detector only in ti2

EN 218 903 ede zede), adsorb negligibly on the surface of the sensor to increase their lifespan from a few months to 10-12 months, and are suitable for in vivo use,

(b) they can be bonded to both the polyvinyl chloride and polyurethane electrode bodies and form a highly adherent layer on a solid surface;

(c) they are mechanically resistant and therefore not vulnerable and not pressure sensitive.

Claims (2)

PATENT CLAIMS CLAIMS 1. A biocompatible ion-selective electrode solution for determining ion concentration and / or ion activity of a complexing compound or precipitate of a plastic membrane containing an active substance comprising a tubularly formed plastic electrode body comprising: or a electrolyte solution having a constant ionic activity, the latter being a potential drain, characterized in that the sensing element (2) comprises 10 to 80% by weight of polyvinyl chloride and polyvinyl chloride containing carboxyl and / or hydroxyl functional groups. , the sensing element (2) having a molecular weight of 1.2-2.4% by weight of active material, preferably valinomycin, or in a solvent, and optionally 40-60% by weight of plasticizer and 0.2-0.5% by weight Contains% Additive. A biocompatible ion-selective electrode according to claim 1, characterized in that the sensing element (2) comprises a surface-treated disperse or diffusive support phase impregnated with an active substance or a solvent dissolved in a solvent, preferably a web.