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.