Mesoporous Fe2O3-CdS Heterostructures for Real-Time Photoelectrochemical Dynamic Probing of Cu2+

A three-dimensional (3D) mesoporous Fe2O3-CdS nanopyramid heterostructure is developed for solar-driven, real-time, and selective photoelectrochemical sensing of Cu2+ in the living cells. Fabrication of the mesoporous Fe2O3 nanopyramids is realized by an interfacial aligned growth and self-assembly process, based on the van der drift model and subsequent selective in situ growth of CdS nanocrystals. The as-prepared mesoporous Fe2O3-CdS heterostructures achieve significant enhancement (similar to 3-fold) in the photocurrent density compared to pristine mesoporous Fe2O3, which is attributed to the unique mesoporous heterostructures with multiple features including excellent flexibility, high surface area (similar to 87 m(2)/g), and large pore size (similar to 20 nm), enabling the PEC performance enhancement by facilitating ion transport and providing more active electrochemical reaction sites. In addition, the introduction of Cu2+ enables the activation of quenching the charge transfer efficiency, thus leading to sensitive photoelectrochemical recording of Cu2+ level in buffer and cellular environments. Furthermore, real-time monitoring (similar to 0.5 nM) of Cu2+ released from apoptotic HeLa cell is performed using the as-prepared 3D mesoporous Fe2O3 CdS sensor, suggesting the capability of studying the nanomaterial cell interfaces and illuminating the role of Cu2+ as trace element.