Fabricating Self-powered Paper-based Microfluidic Analytical Devices Triggered By Biological Enzymes For Electrochemical Biosensing

With the progress of science and technology,in recent years,portable self-powered paper chips have played an important role in the fields of public health safety,food safety and environmental pollution monitoring and treatment.In t he process of monitoring,traditional electrochemical biosensors need external power and complex equipment,which cannot realize rapid monitoring in the point-of-care testing.Due to the advantages of porous,flexible,low-cost,easy to fabricate and use,paper provides a favorable tool for the construction of miniaturized,implantable or portable devices.Nanomaterials have the advantages of good biocompatibility,large specific surface area and high conductivity,which lays a foundation for the preparation of high-performance self-powered paper chips.The enzyme biofuel cell-based self-powered electrochemical biosensor can collect the energy in the environment and realize the self-supply of electricity for sensing by means of electrochemistry.The low bio-enzyme loading and slow electron transfer rate will greatly reduce the performance of the sensor.In this paper,a self-powered electrochemical biosensor was designed by combining combining the triggering effect of bio-enzymes with different nanomaterials.Metal nanoparticles or metal oxide nanomaterials with different structures were grown in situ on the surface of paper fibers as conductive substrates,and combined with bio-enzymes and biomolecules to regulate the signal response of electrochemical sensing,which realized the construction of self-powered paper chips triggered by bio-enzymes.The research work has been carried out as follows:（1）A self-powered origami sensor with a pop-up structure was designed using paper as the substrate because of its easy folding and porous characteristics.Gold nanoparticles were grown in situ in the detection area to improve the conductivity of the substrate and connect DNA strands.Glucose oxidase（GOx）was immobilized through the hybridization reaction of the chain.The presence of the target will trigger the releasing of GOx.GOx in different positions can undergo different oxidation-reduction reactions to realize the detection of differential pulse voltammetry/supercapacitor by changing the direction of the pop-up structure.The introduction of supercapacitors could amplify the readout of signals,thereby improving the sensitivity of self-powered electrochemical biosensor.（2）An enzyme biofuel cell-based self-powered three-dimensional origami biochip was designed to detect prostate-specific antigen.The key components were composed of GOx/gold nanoparticles/ZnO nanorods hybrid anode and bilirubin oxidase/Pt Ni nanocube（BOD/Pt Ni NCs）bioconjugated aptamer functionalized biocathode.Gold nanoparticles functionalized paper chip was prepared to solve the problem of poor conductivity and increase the effective active area.ZnO nanorods were prepared on the anode by secondary in-situ growth method to increase the enzyme loading and the electron transfer rate between the redox center and the substrate.Bilirubin oxidase/Pt Ni NCs bioconjugate was used to synergically catalyze O₂ reduction and regulate the electrochemical signal response to achieve high signal output of the target,expanding the application of self-powered paper chips in the field of medical diagnosis.