Research On Photoelectrochemical Biosensing System Based On Smartphone

As a newly developed and promising analytical method,photoelectrochemical(PEC)analysis has been widely used in biosensing,medical monitoring,environmental monitoring,and food analysis.PEC analysis uses light as excitation source to stimulate photoactive materials to generate electron-hole pairs,which can generate photocurrent that can be detected by external circuits.Given the separation of excitation source and detection signal,the sensitivity of PEC analysis is high and the background noise is low.Traditional PEC analysis relies on the synergistic action of electrochemical workstation and high-power light source.The increasing demands of point-of-care(POC)testing put forward new requirements for the miniaturization and portability of PEC detection devices.Smartphone plays an important role in mobile sensing due to its advantages of high-speed computing,wireless communication,and open source operation.By combining integrated circuit technology,it is conducive to building an“integrated”detection platform for photoelectric integration,which provides a new idea for the practical application of PEC sensing.In this paper,we developed a smartphone-based photoelectrochemical biosensing system to realize the portability and miniaturization of PEC detection devices,so as to realize the real-time PEC detection of biomarkers.This system mainly consists of three parts:smartphone,detection circuit,and biosensors.Smartphone is the control center of the whole system,which is used for parameters setting,information interaction,data processing and display.The detection circuit integrates the functions of high-power light source and electrochemical workstation to realize simultaneous control of light excitation and photocurrent measurements.Biosensors are mainly utilized to detect target substances.Firstly,we constructed the hardware and software of the system.By selecting the appropriate integrated circuit chips and light emitting diodes,the hardware circuit was designed and processed.Through a series of photocurrent and performance tests,the feasibility analysis of the hardware circuit was completed.The measurement results of this circuit were in good agreement with those of electrochemical workstation.Then,we completed the development of smartphone application by using programming software,and realized the wireless communication between hardware circuit and smartphone application via Bluetooth.Secondly,we constructed the biosensors,especially the electrodes.In this paper,graphitic carbon nitride(g-C₃N₄)with visible photoelectric response was selected as photoactive material,and gold nanoparticles(Au NPs)were utilized as signal amplification elements.The electrodes were characterized by electron microscopy,spectroscopy,and electrochemistry.In addition,according to the requirements of portable detection,we also designed the PEC reaction device to meet the need of real-time detection.On the basis of the above system construction,we selected the corresponding target to analyze the feasibility of the system.Matrix metalloproteinase-2(MMP-2),an important cancer marker,was selected as an example in this paper.As an endopeptidase,MMP-2 can cleave peptide sequences(PLGVR)specifically.Therefore,based on the principle of peptide cleavage,we prepared specific peptide sequences and immobilized it to the surface of the electrodes.Then,the PEC detection system based on smartphone constructed in this paper was used to detect MMP-2 with different concentrations,and the linear relationship between the concentrations of MMP-2 and the photocurrents was obtained.The stability and specificity of the biosensors were also tested.The results showed that this system could realize rapid detection of MMP-2,which is of great significance in the early diagnosis and prognosis of cancer,and screening of anti-cancer drugs.In general,the miniaturized and portable PEC biosensing system based on smartphone provides possibilities for the practical application of PEC biosensors in the fields of biomedical and environmental monitoring.