Near-Infrared-Responsive Photoelectrochemical Aptasensing Platform Based on Plasmonic Nanoparticle-Decorated Two-Dimensional Photonic Crystals

The photoelectrochemical (PEC) analysis is an emerging and fast developing biosensing technique. However, the in vivo PEC biosensing in deep tissue is seriously hampered because of the shallow penetration depth of ultraviolet and visible light. Expanding the optical absorption wavelength of photoelectrodes from the visible light region into the near-infrared (NIR) light region is highly desirable because of its deep tissue penetrability and minimal invasiveness for organisms, but the exploration of the facile strategy to implement efficient NIR absorption with good biocompatibility is still challenging. Herein, a NIR PEC aptasensor is proposed by coupling plasmonic nanoparticles (NPs) into periodic two-dimensional nanocavity (NC) photonic crystals as photoelectrodes, where the Au NPs are sputtered on a periodic two-dimensional TiO₂ NC photonic crystal substrate to significantly enhance the NIR PEC response and successfully achieve sensitive PEC detection of Hg²⁺ under irradiation of NIR light in blood. We believe that the proposed NIR-responsive Au/TiO₂ NC-based PEC aptasensor will open a new in vivo biosensing model for a series of important biomolecules and pave up an avenue for the practical applications of PEC biosensing in deep tissue or even in organs and brain of the living body.