One step polymerization of [2-(methacryloyloxy)-ethyl trimethyl ammonium chloride] (METAC) onto the surface of silicon dioxide nanopowder (SDNP) has been carried out to achieve quaternized polymer/nanosilica composite. Various aspects of a quaternized polymer (such as anion selectivity, ion exchange capacity, biocompatibility and antibacterial activity) have been evaluated for the possible applications in analytical and biomedical fields. The composite has been characterized by FTIR, TGA, TEM, and chemical and biochemical analysis. The role of SDNP in polymerizing METAC has been elucidated. The core-shell structure of the composite favors chromate selectivity and desireable bioactivity.