Facile Synthesis of Poly ( N-isopropylacrylamide) Coated SiO2 Core-shell Microspheres via Surface-initiated Atom Transfer Radical Polymerization for H2O2 Biosensor Applications.

In this study, inorganic/organic composites containing poly (N-isopropylacrylamide) coated core-shell SiO2 microspheres were prepared via surface-initiated atom transfer radical polymerization (ATRP). The thermal responsive polymer, N-isopropylacrylamide was treated with methanol, water and CuBr/CuBr2/1,1,4,7,7-pentamethyldiethylenetriamine (PMDETA) at room temperature to form PNIPAM@SiO2 microspheres. The as-prepared PNIPAM@SiO2 microspheres were characterized by FT-IR, TGA, XPS, SEM, TEM analyses. Hemoglobin (Hb) was immobilized onto the surfaces of PNIPAM@SiO2 microspheres via hydrophobic and π-π stacking interactions. The as-prepared Hb/PNIPAM@SiO2 electrode exhibits well-defined redox peak at a formal potential of −0.38 V, validating the direct electrochemistry of Hb. The Hb immobilized composite film retained its bioelectroactivity without any significant loss of catalytic activity. The modified electrode detects H2O2 over a wide linear concentration range (0.1 μM to 333 μM) with a detection limit of 0.07 μM. This modified electrode also successfully detects H2O2 from food and disinfectant samples with appreciable recovery values, validating its practicality. We believe that PNIPAM@SiO2 composite has great potential to be used in the detection of H2O2 and development of other enzyme based biosensors. [ABSTRACT FROM AUTHOR]