Preparation Of Hierarchically Porous Nanocomposite Arrays Modified Carbon Fiber Microelectrode And Its Electrochemical Biosensing Research

Early diagnosis and treatment of cancer has gained more attraction towards the electrochemical biosensing as they have high sensitivity,fast detection,great stability,real time analysis and superb selectivity for in vivo or in vitro detection.Being reactive oxygen species(ROS),hydrogen peroxide(H₂O₂)is similar to tumor cells in physiological activities.In this regard,H₂O₂ plays vital role in the detection of cancer biomarker.Hence,an electrochemical sensor based on 3D hierarchically porous nano-arrays modified carbon fiber microelectrode is developed in this article to detect H₂O₂as well as in situ monitoring of living cancer cells.The main contents of this article are as follows:(1)Designing and preparing a hierarchically porous nitrogen-doped carbon foam arrays loaded with Cu nanoparticles to modify carbon fiber microelectrodes and using them for H₂O₂ sensing.Initially,a highly ordered and densely arranged Cu O nanofoam arrays(Cu O-NFAs)are grown on carbon fiber(CF).A green carbon doping technology is developed by dopamine(DA)self-polymerization to obtain PDA/Cu O-NFAs/CF electrode.After high temperature annealing,PDA film forms a nitrogen-doped carbon layer(NC).Then,the Cu O template is removed by acid etching to uneffect the carbon layer morphology.During the high-temperature carbonization process,Cu O reacts with carbon layer to obtain Cu NPs which in turn to form the N-dope carbon nanofoam arrays(NC-NFAs)and modified CF flexible microelectrode(Cu NPs/NC-NFAs/CF).This enhances the specific surface area along with electrocatalytic activity of the electrode.The sensor system based on the Cu NPs/NC-NFAs/CF microelectrode is used to detect H₂O₂ with a detection limit of 2?M,a linear range of 0.265-1.665 m M,and a sensitivity of 162.7?A cm^-2 m M^-1.(2)Constructing a hierarchically porous nitrogen-doped carbon nanofoam arrays embedded with PdCu alloy nanoparticles modified CF composite electrode,and appling it to detect H₂O₂ released by cancer cells.In order to further improve the catalytic activity of the composite flexible microelectrode for H₂O₂,we developed a novel and facile strategy for the synthesis of a highly active and stable electrocatalyst based on PdCu alloy nanoparticles(PdCu-ANPs)embedded in 3D hierarchically porous NC-NFAs,which were assembled on flexible CF microelectrode for in situ sensitive electrochemical detection of biomarker H₂O₂.Utilizing the reducibility of PDA to modify Pd nanoparticles on the surface of PDA/Cu O-NFAs/CF.Cu atoms generated during high-temperature carbonization combine with Pd atoms to form PdCu-alloy nanoparticles(PdCu-ANPs)which are embedded on the surface of the electrode material in the annealing process.NC-NFAs embedded with PdCu-ANPs modified CF flexible composite microelectrode(PdCu-ANPs/NC-NFAs/CF)is finally prepared after acid etching Cu O template.The ECSA of the composite electrode is 6 times larger than that of CF.The results show that the unique hierarchically porous structure of NC-NFAs provides a large surface area for embeding high-density PdCu-ANPs and promotes mass transfer and molecular diffusion during electrochemical reactions.Utilizing the unique structural advantages of NC-NFAs scaffold and the excellent electrocatalytic performance of PdCu-ANPs,PdCu-ANPs/NC-NFAs/CF microelectrode shows good electrochemical sensing performance for H₂O₂,including a wide linear range up to 3.44 m M,detection limit as low as 500 n M,and good reproducibility,stability and anti-interference ability.When real-time in situ tracking H₂O₂ secreted by different types of human colorectal cancer cells HCT116,HT29,SW48 and Lo Vo,this microelectrode can distinguish cancer cells by measuring the number of extracellular H₂O₂ molecules released by each cell,which shows a great prospect in the early diagnosis and treatment of cancer.