This research describes the preparation and sensor applications of multifunctional monodisperse, Fe 3O 4 nanoparticles-embedded poly(styrene)/poly(thiophene) (Fe 3O 4-PSt/PTh), core/shell nanoparticles. Monodisperse Fe 3O 4-PSt/PTh nanoparticles were prepared by free-radical combination (mini-emulsion/emulsion) polymerization for Fe 3O 4-PSt core and oxidative seeded emulsion polymerization for PTh shell in the presence of FeCl 3/H 2O 2 as a redox catalyst, respectively. For applicability of Fe 3O 4-PSt/PTh as sensors, Fe 3O 4-PSt/PTh-immobilized poly(ethylene glycol) (PEG)-based hydrogels were fabricated by photolithography. The hydrogel patterns showed a good sensing performance under different H 2O 2 concentrations. They also showed a quenching sensitivity of 1 μg/mL for the Pd 2+ metal ion within 1 min. The hydrogel micropatterns not only provide a fast water uptake property but also suggest the feasibility of both H 2O 2 and Pd 2+ detection.
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