Polydopamine-templated synthesis of metal oxide hollow nanospheres for electrochemically detecting hydrogen peroxide released by cancer cells
Abstract
This study presents a facile biomimetic synthesis of metal oxide hollow nanospheres (HNSs) using polydopamine (PDA) templates for electrochemical H2O2 sensing. Monodispersed PDA spheres (350 nm) enabled controlled fabrication of TiO2, Mn2O3, and CeO2 HNSs via calcination (550 °C), yielding uniform hollow structures with 10 nm shells. The TiO2 HNS material's inherent electrocatalytic properties, particularly its ability to facilitate electron transfer during the reduction of H2O2, were enhanced by the HNS design. The HNS structure dramatically increased the effective surface area, accelerating H2O2 adsorption and promoting highly efficient reaction kinetics. The TiO2 HNS-modified electrode demonstrated exceptional catalytic activity, achieving a 4.0 nM detection limit and a 0.01–7.5 μM linear range for H2O2 reduction at −0.6 V (vs. SCE). The sensor showed >93% stability over 15 days and excellent selectivity against biological interferents. The provided method was successfully used for the rapid determination of hydrogen peroxide released by cancer cells, particularly human cervical cancer cells (HeLa cells) and human breast cancer cells (MCF-7 cells). The PDA-templating method offers advantages over conventional approaches through ambient-pressure processing and precise morphological control. Due to their highly active surfaces, the synthesized HNSs are promising candidates for biosensor fabrication.