EFFECT OF SiO2 AND Ag NANO-PARTICLES ON THE SENSITIVITY OF COLORIMETRIC COLESTEROL BIOSENSOR

Abstract

A biosensor comprises a biorecognition molecule immobilized over a signal transducer to give a reagentless analytical device. The biorecognition molecules, such as enzyme, antibody, sequence of DNA, peptide or even a microorganism, provide the biosensor with its selectivity for the target analyte so that the molecule of interest can be picked out by the biosensor from a matrix of many other molecules. The fundamental property of biosensor is its sensitivity of detecting even a small amount of sample and by the use of nanoparticles the sensitivity has been increased with faster response time. So, the main aim of any biosensor is to have high sensitivity and various nanoparticles like silver and silica, which have tendency to increase the sensitivity has been used. Silver nanoparticle has excellent electrical conductivity and optical properties. Silver nanoparticle is effective in the H2O2 reduction as, it enhances the reducing capability of H2O2 and hence increases the sensitivity of detection of cholesterol. Silica nanoparticles are hydrophilic and biocompatible in biological environment. Dye-conjugated with silica nanoparticles have been sensitive in detecting even a very small amount of cholesterol. Their flexible conjugation, excellent photostability, and ultrasensitivity make them a powerful tool in bioanalysis. Hence dye conjugated with silica nanoparticle enhances the sensitivity by enhancing the colour the of solution also the stability of dye was greatly enhanced in presence of silica nanoparticles.