AgInSe2-Sensitized ZnO Nanoflower Wide-Spectrum Response Photoelectrochemical/Visual Sensing Platform via Au@Nanorod-Anchored CeO2 Octahedron Regulated Signal

Herein an ultrasensitive photoelectrochemical (PEC)/visual biosensor coupled with a multiple signal amplification strategy was proposed for the detection of nucleic acids. The initial signal amplification was achieved via ternary AgInSe2 quantum dot (QD)-sensitized ZnO nanoflowers (ZnO NFs) to form an excellent photoelectric layer. A gold-modified nanorod-anchored CeO2 (Au@NR-CeO2) octahedron was introduced as a multifunctional signal regulator via the formation of triple helix molecules. The Au@NR-CeO2 octahedron could not only quench the photocurrent signal due to the competitive capture of photon energy and electron donors with the photoelectric layer but could also act like a peroxidase to catalyze the formation of mimetic enzymatic catalytic precipitation (MECP) on the surface of the photoelectric layer. Furthermore, the steric hindrance effect from the Au@NR-CeO2 octahedron further reduced the output of the photocurrent signal. After incubation with t-DNA, the triple helix conformation was disassembled and the Au@NR-CeO2 octahedron was released from the electrode surface, leading to the significant increase of photocurrent signal. Meanwhile, the released Au@NR-CeO2 octahedron could flow into the colorimetric area of the lab-on-paper device to catalyze the occurrence of the color reaction, achieving a visual detection for t-DNA. On the basis of the multiple signal amplification strategy, t-DNA was detected specifically with a lower limit of detection of 0.28 fM and a wider linear range from 0.5 fM to 50 nM. The proposed method has the potential utility to detect a variety of nucleic acids and biomarkers.