Damage-free Photoelectrochemical Cell Sensor Based On Low Toxicity Materials And Driven By Red Light

Cell is the fundamental building unit of biological structure and functions,and the research on cell is closely related with the development of life science,clinical treatment and diagnosis as well as public health.With the gradually increased incidence of disease,cancer has become the current leading killer of human health.Thus,the development of highly sensitive detection method towards cancer cells has become the key point for improving human health.The expression levels of intracellular small molecules,protein across the cell membrane and the intracellular pH changes would be obviously changed with the cancerization or pathological change of cells.Based on these changes,effective diagnosis of cancer cells can be achieved.Photoelectrochemical(PEC)bioanalysis is a novel analytical method which integrates PEC process and biological analysis.In PEC analysis,the excitation light source and detection signal are two independent parts,which can avoid the interference of background signal compared with the traditional electrochemical analysis techniques.Therefore,based on this novel technique,better sensitivity can be obtained,which attracted high attentions.In recent years,PEC bioanalysis technology has been successfully applied in detecting a variety of biological substances,such as nucleic acid,protein,enzyme,cell and intracellular small molecule substances.However,the traditional photoelectrochemical sensing system is mostly based on materials containing heavy metal elements,such as the lead and cadmium.Besides,the wavelength of the excitation light source is usually located in the UV-visible range.The material toxicity and short-wavelength excitation light are both harmful to biological samples,which limits its further development,especially in cell detection.Thus,the development of low toxicity photosensitive material driven by long wavelength light(red light)has great significance for photoelectrochemical biosensors.In this paper,based on low toxic ternary inorganic semiconductor nanomaterials and their composites,cells and cells related substances were detected by red light-driven PEC technology.The detailed works are as follows:1.Based on the dye sensitized AZIS quantum dots(QDs),a label-free photoelectrochemical cytosensing platform driven by red light has been developed.Compared with the undoped Zn-In-S QDs,the Ag doped Zn-In-S QDs synthesized by hydrothermal method showed higher absorption efficiency towards red light and the photocurrent signal intensity increased by 7 times.The composite formed by ultrasonic mixing of FePc and AZIS QDs was applied as the signal source for PEC detection,which also significantly improves the generation ability of photocurrent under red light.Hyaluronic acid(HA)can recognize the overexpressed CD44 protein on the surface of A549 cells.Therefore,the amide reaction between the carboxyl group on the surface of HA and the amino group on the surface of the composite material was used to modify it on the surface of the electrode and an efficient PEC cytosensing platform was proposed for the ultra-sensitive detection of A549 cells.After the cell capture on the electrode surface,the photocurrent intensity of the composite material decreased sharply due to the huge steric hindrance effect.The concentration of A549 cells were quantized by the change of photocurrent before and after the cell capture.The linear concentration range of A549 cells detected by the cytosensor was 2×102-4.5×106 cells/mL,and the detection limit was 15 cells/mL at the signal to noise ratio of 3.The sensor has the advantages of high sensitivity and good stability,and can be applied as an ideal platform for the detection of other biomolecules.2.A novel photoelectrochemical biosensor platform driven by red light based on low-toxic AgInS2 nanoparticles(NPs)capped with 3-mercaptopropionic acid(MPA)is proposed.The AgInS2 NPs with excellent water solubility and biocompatibility was used as the photoactive material to construct cytosensor.Under the excitation of red light,the material showed high photocurrent conversion efficiency and generates strong photocurrent signal,which significantly improves the sensitivity of PEC detection.The amino-terminal modified sgc8c aptamer was immobilized on the AgInS2 NPs modified electrode.The aptamer could effectively capture the overexpressed tyrosine protein kinase on the surface of CCRF-CEM cells.Therefore,CCRF-CEM cells were used as the analyte model.After the capture of CCRF-CEM cells on the electrode surface,the photocurrent intensity was significantly decreased.Under the light excitation of 630 nm and the applied potential of 0.15 V,an ultrasensitive and non-destructive PEC detection platform was designed.The PEC cytosensor possesses wide linear response range,low detection limit,high specificity,low cytotoxicity and excellent analytical performance.Based on this platform,a detection limit of 16 cells/mL was obtained at the signal to noise ratio of 3.This work not only expands the application of ternary semiconductor nanomaterials in photoelectrochemical biosensors,but also provides a non-destructive assay for the early clinical diagnosis of cancer.