Biomedical subjects

T Hianik

Publications and source records attributed to T Hianik.

59 records · Page 4Linked to original sources

PubMedDate not supplied

Glucose biosensors based on dendrimer monolayers.

The peculiarities of glucose biosensors based on different generation of dendrimers (G0, G1 and G4) have been studied by amperometry and QCM techniques. It is shown that stable glucose biosensor can be obtained with low generation of dendrimers. The sensor sensitivity, however considerable, increased with increasing number of generation of dendrimers. This can be due to the increased volume of the dendrimer interior as well as with increased number of binding sites for glucose oxidase (GOX). QCM experiments showed that immobilization of GOX resulted in formation of enzyme multilayers on a dendrimer surface. The enzyme turnover for this system (0.1-0.01 s(-1)) was lower then that for immobilization of GOX onto a supported lipid films by means of avidin-biotin technology (1.1 s(-1)). However, dendrimer based biosensors are more stable in comparison with sBLM based sensors and could be stored in a refrigerator in dry conditions over 15 days without substantial loss of sensitivity.

Journal Article↗

PubMedDate not supplied

[Relation between gramicidin D and valinomycin-induced conductivity of lipid bilayer and cholesterol levels].

Kinetics of conductance and current-voltage characteristics (VACH) were studied on the bilayer lipid membranes from egg lecithin and cholesterol modified by gramicidin D and valinomycin. There were found significant changes of ionic channels conductance g, lifetime tau and non-linearity coefficient beta of VACH of modified membranes dependent on cholesterol content. In the region of high cholesterol concentrations, more than 20 mol%, there were observed abrupt changes of the ionic channels parameters: tau increased more than ten times, conductance decreased two times and beta greater than 0 in the whole region of electrolyte concentration.

Cholesterol↗

PubMedDate not supplied

[Calcium-induced changes in bilayer membranes from oxidized cholesterol].

Elastic properties of oxidized cholesterol bilayers in n-octane and membrane solvent free were studied by measuring Young modulus E perpendicular in the direction perpendicular to the membrane plane as a function of concentration of calcium ions. Interaction between calcium ions and solvent free bilayers resulted in a significant increases of Young modulus E perpendicular in the concentration range 20-40 mmol/l Ca2+. It is suggested that the hardening of the membrane is caused by some structural changes in the hydrophobic region of the membrane.

Calcium↗

PubMedDate not supplied

[Conductivity fluctuation of lipid bilayer membranes formed on a substrate].

In the range of voltages -0.9-(+)0.9 V the fluctuations of conductivity of bilayer lipid membranes formed on the support (s-BLM) were measured. The new cut of the wire from stainless steel SS-10T served as the support. The similarity of current fluctuations for s-BLM as well as for support-electrolyte interface was observed, some quantitative distinctions are revealed. Three types of fluctuations are observed; 1) large current jumps observed as current steps at DC channel; 2) small current fluctuations near zero line with the spectrum of 1/f alpha type (flicker noise); 3) short current jumps, whose amplitudes are many folds higher than mean noise level, and the density of distribution function falls off as fluctuation magnitude raised to power 2.5 for s-BLM.

Animals↗

PubMedDate not supplied

[Current-voltage characteristics of bilayer lipid membranes formed on the substrates].

Current-voltage characteristics (CVC) of bilayer lipid membranes formed on the support (s-BLM) were measured in static mode as well as in cyclic one with the period 33 s. The new cut of the wire from stainless stell SS-10T served as the support. In the range of voltages -0.9-(+)0.9V the similarity of the CVC for s-BLM as well as for support- electrolyte border was observed. Static CVC for both objects satisfy the Tafel's equation with close parameters. If the voltage amplitudes were over 0.3 V, s-BLM specific capacitance approached the same value for the support-electrolyte border. Possible electrical models of s-BLM are discussed.

Lipid Bilayers↗