In-Situ Synthesis of Nanosized TiO2 within Zwitterionic Spherical Polyelectrolyte Brushes toward Antibacterial and Antiprotein Adsorption Coating

Developing a multifunctional coating with reduced fouling and antibacterial activity remains challenging. In this investigation, zwitterionic spherical polyelectrolyte brushes (SPB) were employed as nanoreactors for the in situ synthesis of nanosized TiO2, resulting in SPB@TiO2 hybrid nanounits with controlled inorganic distribution. Small-angle X-ray scattering (SAXS) confirmed that TiO2 was successfully immobilized within the brush layer and preferentially enriched in the inner shell region. SAXS data indicated that the SPB@TiO2 retained very low protein adsorption due to the zwitterionic polyelectrolyte structure. When SPB@TiO2 was integrated into a quaternary ammonium chitosan (QCS) matrix to assemble coating-oriented materials driven by electrostatic interactions, the resulting complexes exhibited enhanced antibacterial activity against Escherichia coli and Staphylococcus aureus, with antibacterial rates of 98.0% and 99.0%, respectively, upon UV irradiation. This work provides a practical route to hybrid surface antibacterial coatings through in situ inorganic incorporation and polymer complexation.