Authors: S.J. Newati, V.M. Singh, S. Sachdeva, R.A. Khan
Affilation: Manav Rachna International University(MRIU), India
Pages: 39 - 42
Keywords: biosensor, self-assembled monolayers, enzyme, cholesterol oxidase, cystemine, iron oxide (Fe2O3) nanoparticles, electrochemical impedence
The immobilization of biomolecules on solid support is crucial component in fabrication of biosensors. The self assembled monolayers (SAM) can be used for fabrication of the biosensor-component that allows chemically reactive functional group manipulations for making compatible immobilizations. The enzyme, cholesterol oxidase (ChOx) was covalently attached to cysteamine (Cyst) self-assembled monolayers on gold–sheeted (Au) glass-plates and reinforced with iron-oxide (Fe2O3) nanoparticles. The Fe2O3-ChOx-Cyst-Au bioelectrodes were characterized by measuring changes in contact angles in the gradually transforming hydrophilicity versus lipophilicity which was measured for the consecutively stratified bioelectrodes at each stage of fabrication. The bare gold-sheet showed contact angle at 84.120 and as Cyst-SAM, ChOx enzyme layer were deposited and Fe2O3 nanoparticles were adsorbed on the solid support, the contact angle changed continually. The Fe2O3-ChOx-Cyst-Au bioelectrode showed the final contact angle at 74.740 confirming the formation of desired electrode. The FT-IR spectroscopy and Scanning Electron Micrographs also unambiguously confirmed the formation of Fe2O3-ChOx-Cyst-Au and adsorption of iron nanoparticles. The Fe2O3-ChOx-Cyst-Au electrode convincingly estimated the cholesterol concentration in known test samples. The developed biosensor was found to have linearity from 50-400 mg/dL with the detection limit of 50 mg/dL. The shelf-life was found about 4 weeks with 30 times reusability capability of the electrode. Furthermore, it was observed that the iron oxide nanoparticles reinforcement on electrode increased the shelf-life and its over-all working stability.