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In this study, antibacterial properties were induced in polyurethane (PU) films by the incorporation of Ag þ -loaded zeolites as fillers. The mechanical and thermal properties of the prepared composites were also investigated. For this purpose, two different types of zeolite microparticles, high-silica zeolite beta crystals and low-silica zeolite A crystals, were synthesized. Ag þ was added by ion exchange, and these particles were incorporated into the PU prepolymer, which was prepared from its main components of toluene diisocyanate and polypropylene ethylene glycol (medical purity). Microbiological tests revealed that both types of composites, prepared by the addition of Ag þ -containing zeolite beta or zeolite A to the PU matrix, had antibacterial properties. It was demonstrated for the first time that a high-silica zeolite (zeolite beta) and its composite film could be effectively employed as antibacterial materials. Furthermore, mechanical and thermal characterization of the composites showed that the zeolites enhanced the mechanical properties of the polymer and did not cause any deterioration in its thermal properties.

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Development of a conductometric biosensor for the urea detection has been reported. It was created using a non-typical method of the recombinant urease immobilization via adsorption on nanoporous particles of silicalite. It should be noted that this biosensor has a number of advantages, such as simple and fast performance, the absence of toxic compounds during biosensor preparation, and high reproducibility (RSD = 5.1 %). The linear range of urea determination by using the biosensor was 0.05–15 mM, and a lower limit of urea detection was 20 μM. The bioselective element was found to be stable for 19 days. The characteristics of recombinant urease-based biomembranes, such as dependence of responses on the protein and ion concentrations, were investigated. It is shown that the developed biosensor can be successfully used for the urea analysis during renal dialysis.

Incorporation of zeolite into polyurethane (PU) membranes was investigated by using as-synthesized and calcined zeolite beta particles at two different loading contents (0.1 and 1 wt %). The chemical interaction between the zeolite beta crystals and PU was observed by ATR-FTIR spectroscopy. The SEM results suggested that the calcined zeolite beta crystals were more homogeneously dispersed in the composite membranes than the assynthesized zeolite beta crystals. DMA results demonstrated that all composite membranes had higher storage modulus in the rubbery state and higher stability towards thermal and mechanical degradation with respect to the control groups. Tensile testing results also showed increased tensile strength and elongation at break for all composite membranes. This study suggests that incorporating zeolite beta in its as-synthesized or calcined forms and at different amounts can be applied as an alternative method for tailoring the mechanical properties of PU membranes without changing its structural characteristics.

In this work, we developed a new amperometric biosensor for glutamate detection using a typical method of glutamate oxidase (GlOx) immobilization via adsorption on silicalite particles. The disc platinum electrode (d = 0.4 mm) was used as the amperometric sensor. The procedure of biosensor preparation was optimized. The main parameters of modifying amperometric transducers with a silicalite layer were determined along with the procedure of GlOx adsorption on this layer. The biosensors based on GlOx adsorbed on silicalite demonstrated high sensitivity to glutamate. The linear range of detection was from 2.5 to 450 μM, and the limit of glutamate detection was 1 μM. It was shown that the proposed biosensors were characterized by good response reproducibility during hours of continuous work and operational stability for several days. The developed biosensors could be applied for determination of glutamate in real samples.

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