Biosensor based on enzyme coupled PVC reaction cell for electrochemical measurement of serum total cholesterol

Polyvinyl chloride (PVC) being chemically inert and corrosive resistant with ease in molding to various shapes and size, was used to fabricate enzyme reaction beaker which acts as electrochemical cell for three electrode-based system for measurement of serum total cholesterol. Inner bottom surface of PVC beaker (15 mL) was chemically modified for covalent immobilization of cholestryl esterase and cholesterol oxidase using glutaraldehyde as a coupling agent. HRP incorporated carbon paste working electrode was fabricated for amperometric measurement at a potential of −50 mV. The sensor showed optimum response within 20 s at pH 7.0 with incubation temperature of 45 °C. Km and Vmax for cholesteryl acetate were 760 mg dL−1 and 0.9 mA s−1, respectively. The PVC-based electrochemical cell showed a correlation of 0.9916, with the values estimated with a commercially available Bayerʹs Enzo Kit. The reaction cell lost 50% of its initial activity during its regular use for 200 times over a period of 100 days when stored in 0.1 M sodium phosphate buffer, pH 7.0 at 4 °C. No metabolite interference was observed. The overall results strengthen our view that PVC can be used as a solid support for immobilization of enzymes and their applications in biochemical measurements.