Magnetic CMP microspheres: multifunctional poly(phenylene ethynylene) frameworks with covalently built-in Fe3O4 nanocrystals exhibiting pronounced sensitivity for acetaminophen microdetection

A novel multifunctional conjugated nanoporous polymer colloid (CNPC) combined with metal nanocrystals has been synthesized using the Sonogashira coupling reaction in a toluene-in-water miniemulsion. It is composed of a poly(phenylene ethynylene) (PPE) network that is covalently inlaid with the locked-in Fe3O4 nanocrystals. The Fe3O4@CNPC has a narrowly distributed size and uniform morphology, preserves the advanced porosity and fluorescence emission of the conjugated polymer network, and shows rapid magnetic response and high catalytic activity. The magnetic content can be controlled during the synthesis. This is accompanied by a corresponding enhancement of the size and surface area of the mesopores. In view of those characteristics, Fe3O4@CNPC is able to behave as fluorescence sensor for the detection of phenolic compounds. Acetaminophen (APAP) has been used as a model compound and the test results demonstrate that the Fe3O4-catalyzed oxidation of APAP takes place within the pores of the PPE network in the presence of H2O2. The oxidized intermediates are reactive radicals and can remove electrons from the pi-conjugated PPE network, eventually leading to a decrease or even quenching of its fluorescence. Since the multiple functions of Fe3O4@CNPC fully cooperate, it produces a rapid optical response and superior sensitivity for the detection of APAP at micromolar concentrations.