This thesis is devoted towards the development of polymeric matrices and bioconjugated quantum dots for immuno-based detection of S.typhi in water. Thesis involves the surface modification of nylon membrane by grafting with GMA using free radical graft copolymerization. S.typhi specific IgG immobilized NyM-g-GMA was used as solid phase in development of ELISA for detection of S.typhi. Developed sandwich ELISA was found to be specific, reproducible, reasonably rapid and sensitive with detection limit of 103cells/mL. Developed sandwich ELISA was found to have two-fold higher limit of detection as compared to the assay performed using PS plates. For further validation of the developed immunoassay, water samples were collected from different sources in and around Delhi and tested for various parameters of validation. A method for fluorescence based detection of sandwich immunocomplex of bacteria and antibody conjugated CdSe/ZnS quantum dots on surface modified porous polycarbonate membrane was also developed. Fluorescent aggregates were observed on the anti-Sty IgG immobilized membranes under confocal microscope and semi-quantified using spectral profiling.