The Research Of H-BN Based Photoelectrochemical Aptasensor For Organophosphorus Pesticides Detection

Organophosphorus（OP）pesticides,as an effective insecticide with high durability,are widely used in agriculture.However,a little amount of organophosphorus pesticide residues in water and soil can irreversibly inhibit acetylcholine esterase（ACh E）and accumulate acetylcholine neurotransmitter leading to neurotoxicity symptom even death.Therefore,to detect the concentrations of OP pesticides in environmental samples for public security is still of great necessity and urgency.Generally,various methods can be applied for OP pesticides detection,such as gas chromatographic-mass spectrometry（GC-MS）,surface enhanced Raman scattering（SERS）,high performance liquid chromatography（HPLC）,chemiluminescence techniques and electrochemical strategies.However,these methods are often expensive,complex,time-consuming,and need laboratory based large instrumentation.Therefore,to develop a convenient and sensitive biosensor for detection of OP pesticides certainly is of significance.Photoelectrochemical（PEC）aptasensor as a newly emerged bioanalytical techniques,has attracted considerable attention because of prominent advantages,such as fast response,low background,high sensitivity,simple operation and straightforward detection mechanism.The application of various two-dimensional（2D）layered materials,such as graphene,graphitic carbon nitride（g-C₃N₄）and molybdenum disulfide（MoS₂）,is particularly advantageous to fabricate a PEC biosensing platform.Hexagonal boron nitride（h-BN）,as a 2D n-type semiconductor material with the graphene-like structure,has wide applications in photocatalysis,drug delivery and bioimaging.Meanwhile,h-BN possesses good conductivity,large specific surface areas and high electron mobility,to obtain a good photoelectric conversion efficiency.Therefore,we constructed two different h-BN based PEC aptasensor for ultrasensitivity detection of OP pesticides.The main contents of this study are as follows:1.A novel hexagonal boron nitride（h-BN）based self-powered photoelectrochemical（PEC）aptasensor for ultrasensitive detection of diazinon（DZN）with excellent photoelectric conversion efficiency.It was the first time that h-BN based materials were applied to PEC aptasensor,in which the construction of Z-scheme heterojunction of h-BN and graphitic carbon nitride（CN）via doping sulfur into h-BN was innovatively proposed.Meanwhile,Au nanoparticles（Au NPs）were utilized for the surface plasmon resonance（SPR）effect and the formation of new recombination centers.The charge transfer mechanism was expounded and verified by the electron spin resonance（ESR）spin-trap technique.The proposed PEC aptasensor for determination of DZN exhibited a wide linear range from 0.01 to 10000 nM and a low detection limit of 6.8 pM with superb selectivity and remarkable stability.Moreover,the constructed PEC aptasensor performed well with excellent recoveries in three different real samples.2.A p-type heterojunction CuS QDs/Co₃O₄ polyhedra,by p-n semiconductor quenching effect and mimetic enzymatic catalytic precipitation effect for construction of unmodified h-BN based PEC biosensing platform with low background signal and high sensitivity.Herein,by utilizing ZIF-67 dodecahedra as the precursor,the p-type heterojunction CuS QDs/Co₃O₄ polyhedra with large specific surface areas and porous structure was prepared and used as a multiple signal amplifier for the construction of h-BN biosensing platform for chlorpyrifos PEC assay.In the PEC biosensing platform,the n-type semiconductor h-BN was used as the photoelectrode material,and the p-type heterojunction CuS QDs/Co₃O₄ polyhedra drove the multiple signal amplification to enable the h-BN PEC biosensing platform.The proposed PEC aptasensor for determination of chlorpyrifos exhibited a wide linear range from 1×10^-1to1×10⁷ng ml^-1and a low detection limit of 0.34 pg ml^-1with superb selectivity and remarkable stability.In addition,the constructed PEC aptasensor performed well with excellent recoveries in three different real samples.