A novel kind of hydrogen peroxide (H2O2) photoelectrochemical (PEC) sensor was constructed based on Co3O4 and PbS nanomaterial modified indium tin oxide (ITO) photoelectrode. The Co3O4 nanoparticles, as mimic enzyme of catalase (CAT), can catalyze H2O2 to generate oxygen (O2) in suit. Then the electron acceptor of O2 enhances the cathodic photocurrent of the photoelectrode. The PEC sensor exhibited high sensitivity because of the formation of p–p type heterostructure between PbS and Co3O4 semiconductors. The photocurrent enhancement can be used to detect concentration of H2O2. The calibration plot was linear in the range from 5 to 250 μM, and the detection limit was estimated to be 1.2 μM. The results demonstrated the possibility of nanozyme application in PEC biosensors and the substitution of Co3O4 nanozyme for the natural enzyme.
Chen Ben-Qi,Yang Meng,Liao Wen-Chun,Li Zi-Ying,Chen Zhi-Xiong,Yang Yun-Hui,Yang Tong,Hu Rong
Developing a strategy for the determination of trace ochratoxin A (OTA) in food is very important to ensure food safety. Here, based on a tripod probe, an electrochemical aptasensing platform for detected OTA sensitively was designed, which used the 3D DNA walker by endonuclease Nb.BbvCI
powered and the nanozyme of porous Co3O4 nanodisks loaded Pt nanoparticles (Pt NPs@Co3O4) as a cascaded signal amplifying device. With OTA as a model target, the swing-arm probe of DNA walker was triggered. Next, probe on the magnetic beads was cleaved
and released by Nb.BbvCI to realize the first signal amplification. After that, the partial sequence of the released probe is well assembled with triple-strand DNA by strand reaction and the other sequence exposed as a capture probe was combined with the Pt NPs@Co3O4.
It can efficiently make the decomposition of H2O2, bring about significant current, and the signal was amplified again. The designed electrochemical aptasensor demonstrated outstanding detection linearity in the OTA concentration range of 1 pg/mL to 100 ng/mL, with a
detection limit of 0.194 pg/mL (S/N = 3), with excellent reproducibility and high specificity. It can be used to find OTA in food. This research supplies a potential split-new avenue for the sensitive detection of electrochemical aptasensor.
Cui Zhang,Saiyu Dong,Zhaoli Liu,Nairu Liu,Xi Zhang,Jie Dong,Xueping Zhou,Yirong Guo,Jianxiang Wu
Immunochromatographic test strip (ITS) has been widely employed for point-of-care diagnoses. However, how to significantly enhance the analytical sensitivity of device-free ITS remains a challenge. Here, we synthesized a Cu single-atom anchored Co 3 O 4 (CuSA/Co 3 O 4 ) nanozyme that possesses ultrahigh peroxidase-mimicking catalytic activity owing to d -band center upshift mediated by Cu single-atom. Molecular orbital analysis demonstrated that d orbitals in CuSA/Co 3 O 4 have stronger orbital hybridization affinity than Co 3 O 4 to H 2 O 2 ′s π* orbitals. This reinforces hydroxyl radical ( OH) production and provides a stronger catalytic colorimetric signal, which is beneficial for improving the sensitivity of ITS. Moreover, we applied the CuSA/Co 3 O 4 to ITS as a signal reporter for monitoring Xanthomonas oryzae pv. oryzicola (Xoc) , the pathogen of rice bacterial leaf streak. The visual limit of detection (LOD) of the developed CuSA/Co 3 O 4 -based ITS was as low as 6.4 × 10 2 CFU mL −1 , which is 25-fold more sensitive than the traditional Au nanoparticles (AuNP)-based ITS. Taken together, this work demonstrates the great potential of CuSA/Co 3 O 4 nanocomposite as a signal reporter to improve the sensitivity of ITS for on-site Xoc detection.
危险品化学品经营许可证（带存储）