Provided are encoded polymeric microparticles and a multiplexed bioassay using the encoded polymeric microparticles. Each of the encoded polymeric microparticles includes an encoded polymeric microparticle core and a silica shell surrounding the microparticle core. Further provided is a method for producing encoded polymeric microparticles. The method includes: mixing a photocurable material with a linker having a functional group polymerizable with the photocurable material and an alkoxysilyl group; applying patterned energy to cure the mixture, followed by encoding to obtain encoded polymeric microparticle cores; and treating the encoded polymeric microparticle cores with a silica precursor to form a silica shell on each encoded polymeric microparticle core.