Sammendrag
The field of biosensors is a large and varied one [1]. Biosensor technology has developed into an ever-expanding and multidisciplinary field since the Clark enzyme electrode was first reported. Biosensors generically offer simplified reagent less analysis for a range of biomedical and industrial applications. The bi-molecular layers supported on a gold electrode offers excellent environment for incorporation of bioreceptors [2-4]. Among receptors the calixarenes are of substantial interest. They are relatively new class of macrocyclic molecules containing cavity that specifically bind certain ligand [5]. In this work we prepared self-assembled bilayer lipid membranes supported on a gold surface (sBLM) with incorporated calixarenes sensitive to amino groups. The tOct[6]CH2COOH calixarenes [5] were incorporated into small unilamellar liposomes composed of soy bean phosphatidylcholine in a molar ratio calixarene:lipid=1:10. The lipid layer containing calixarenes has been formed on a surface of gold electrode with chemisorbed octadecanethiol monolayer by liposome fusion [2]. The interaction of dopamine, epinephrine, lysine and cytochrome C (cyt C) with the surface of the sensor has been studied by impedance spectroscopy. The significant changes of sBLM electrcal capacitance started already at 10 nM of cyt C. The interaction of cyt C with the calixarene can be due to lysine residues at the protein surface. However, much higher concentration of lysine (>30 μM) was necessary to induce significant changes of capacitance. Similar sensitivity like for lysine was observed also for dopamine and epinephrine. Thus the sensor revealed substantial sensitivity to cyt C. The potential for usable biosensors based on these types of devices in the medical diagnostic and environmental monitoring applications is immense.
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