POLYSTYRENE NANOPARTICLES BASED IMMUNOASSAY FOR THE DETECTION OF beta-GALACTOSIDASE USING QUARTZ CRYSTAL MICROBALANCE

An immunoassay has been developed for the detection of bacterium Escherichia coli (E. coli) through beta-Galactosidase (beta-Gal). For developing an immunoassay on piezoelectric quartz crystal a polystyrene nanoparticle (PSNP) surface was developed by anchoring synthesized PSNPs (60 +/- 5 nm) via self-assembled monolayer of p-aminothiophenol patterned on gold-coated quartz crystal. In order to make immunoassay specific to beta-Gal, antibody specific to beta-Gal (anti-beta-Bal) was captured through physical attraction. On exposing this immunoassay to the beta-Gal antigen (3.03 ng/ml), a strong detecting signal was observed, with simultaneous detachment of antibody from immunoassay as antigen-antibody complex. No appreciable change in the frequency shift, Delta f, of quartz crystal was observed upon exposure to nonspecific Brucella antigen, confirming the specific behavior of immunoassay.