Structure Regulation Of Nanocarbon For Photoelectrochemical Biosensing

Nanocarbon materials have received enormous attention,due to their excellent physical and chemical properties from unique bonding mode and geometric structure,among multifarious nanomaterials.Interestingly,Nanocarbon materials with abundant functional groups,provide more possibilities for further structure regulation and performance optimization,which are prepared by surface modification and chemical doping.On the one hand,many derivatives can be synthesized by covalent interaction.On the other hand,a variety of nanohybrids can be obtained by noncovalent interaction,such as?-?stacked,electrostatic adsorption,and so on.Furthermore,nanocarbon materials can improve the stability and sensitivity of bioassay,because of inexpensive and simple to obtain,high stability,good biocompatibility and low toxicity for environmental pollution.However,the surface and interface properties of the original nanocarbon materials need to be further improved in order to improve the dynamic process of the sensing signal transduction.Therefore,the goal of this dissertation is to regulate the structure and interface of the nanocarbon materials via noncovalent interaction,improve the dispersibility and photoelectric conversion ability,increase the active sites for conjugating biomolecule of fullerene-based materials,then propose photoelectrochemical biosensors with high sensitivity and selectivity;study the catalytic activity of carbon nanozymes and improve the selectivity and sensitivity of the whole nanozyme system by designing cascade reactions in confined space.The detailed works are summarized as follows:(1)The graphene oxide/thionine hybrid(GO-Th)was prepared by?-?stacked interaction.GO was used as carrier of Th,which can not only accelerate the electron transfer kinetics between electrode and electrochemical probe,but also provide abundant carboxyl for conjugating nanoantibodies.This proposed electrochemical immunosensor detected Cry1C with high selectivity and sensitivity via square wave voltammetry,showing a wide calibration range of 0.01 to 100 ng·m L^-1 and a low detection limit of 3.2 pg·m L^-1.Therefore,this method expanded the application of GO-based electroactive probe in food analysis and environmental monitoring.(2)The fullerene/graphene nanohybrid(AC₆₀-Gr-GO)was prepared by coupling of alkylated fullerene(AC₆₀)with graphite flake(Gr)and graphene oxide(GO)using a simple wet grinding method.Gr in the assemble accelerated the charge-transfer and enhance the photoelectric conversion efficiency of AC₆₀ up to 35 times.Simultaneously,due to abundant carboxyl group active sites,GO in the AC₆₀-Gr-GO guaranteed enough aqueous dispersity and a friendly anchor for facile bioconjugation.The photoelectrochemical immunosensor with high sensitivity and high selectivity to detect alpha-fetoprotein using AC₆₀-Gr-GO as photoelectric active probe,which has explored the application of C₆₀-based nanomaterials in the early disease diagnosis.(3)The long-range ordering donor-acceptor system(C₆₀@PCN-224)was constructed by loading C₆₀ onto the surface and into the pore of the porphyrin-derived MOF(PCN-224)via?-?interaction and physical absorption,which enhanced the photoelectric conversion efficiency.According the proposed mechanism of photoelectric conversion,photogenerated electrons from PCN-224 would transfer to the lowest unoccupied molecular orbital of C₆₀,facilitating the separation of photogenerated electron-hole.Furthermore,the biosensor assay of S100 calcium binding protein,based on photoelectrochemistry,was constructed by taking nanoantibody as biometrics unit.This method not only showed high sensitivity and selectivity,but also opened a new venue for the application of C₆₀ in photoelectrochemical biosensor.(4)The cascade reaction in the confined space was built using Nitrogen doped carbon nanocage(NCNC)and Prussian blue nanoparticles(PB NPs).By comparing NCNC and iron and nitrogen-doped carbon materials with the catalytic oxidation of ascorbic acid(AA),the proper nanozymes were selected and the sequence of nanozyme was designed.The substrates were screened by the cascade reaction step by step,and the catalytic efficiency was improved by the confined apace.Therefore,the whole nanozyme system could detect AA with high selectivity and high sensitivity,which provided a new idea for solving the challenge of low selectivity of nanozyme.