Highly sensitive photoelectrochemical detection of bleomycin based on Au/WS nanorod array as signal matrix and Ag/ZnMOF nanozyme as multifunctional amplifier.

An ultrasensitive photoelectrochemical (PEC) biosensor was constructed based on gold nanoparticles (Au NPs)/tungsten sulfide nanorod array (WS NA) photoelectrode as the PEC matrix and silver nanoparticles/flake-like zinc metal-organic framework (Ag/ZnMOF) nanozyme with the peroxidase mimetic enzyme property for sensitive detection of bleomycin (BLM). In particular, Au/WS and Ag/ZnMOF were linked by thiolate DNA and DNA strand, respectively, and the Au/WS-Ag/ZnMOF probe was prepared via hybridization reaction between the two DNAs. The introduction of Ag/ZnMOF in the probe offers two functions: i) the steric hindrance effect can effectively impede electron transport and reduce the photocurrent; ii) Ag/ZnMOF nanozyme can also be used as mimic peroxidase to effectively catalyze 3,3-diaminobenzidine (DAB) to produce the relevant precipitation, which will further reduce photocurrent and eliminate false positive signals. When BLM exists, BLM with Fe as irreversible cofactor can specifically recognize and cleave of the 5'-GC-3' active site of DNA, resulting in reduced precipitation deposited on the electrode and recovery of PEC signal. The highly sensitive PEC biosensor exhibits a the linear strategy from 0.5 nM to 500 nM with a detection limit down to 0.18 nM. Further, the unique strategy was conducted in biological samples for BLM detection with satisfactory consequence, offering available and efficient pathway for disease diagnosis.