Application Research Of Photoelectric Conversion In The Field Of Cell Detection And Antibacterial

Since the essence and connection between light energy and electric energy have been elucidated,the transformation technology between them has been developed rapidly.Electrochemistry,combined with photochemical and chemiluminescence,has developed photoelectric chemistry and electrochemical luminescence.The former can convert light energy into electricity,the latter can convert electrical energy into light energy.Compared with traditional methods of chemical analysis,photoelectrochemical analysis and electrochemical luminescence have the advantages of low background signal,high sensitivity and simple operation.High photoelectric conversion efficiency is the determining factor of photoelectric materials,so the development of new biocompatible photoelectric active materials with high photoelectric responsiveness is a hot topic in the field of bioapplication.Analytical detection is one of the main research directions of electrochemical luminescence.Therefore,it is desirable to develop new application fields by using electrochemical luminescence.In this context,this thesis is divided into two parts.(1)The development of quantum dots and carbon nanomaterials composites,titanium dioxide and gold nanoparticle composites and cationic polymers with excellent photoelectric properties as photoelectric active material for application as biosensor in cancer cells and its internal microRNAs detection;(2)To use electrochemiluminescent(ECL)signal to excite photosensitive material OPV sensitization and produce active oxygen,which is used in the field of sterilization.The work contents are as follows:Firstly,A label-free photoelectrochemical(PEC)cytosensing strategy was designed based on the excellent PEC activity of carbon dot(C-dot)-cysteamine capped gold nanoparticles(AuNPs-Cys)conjugates.The perfect spectral overlap between the C-dots and the AuNPs-Cys guarantees the generation of resonant energy transfer(RET).The efficient RET process excited more electron-hole pairs in the C-dots and promoted hot electron stored in AuNPs-Cys transfered to the C-dots,significantly increased the photocurrent of the C-dots.The use of HeLa cells,which were captured via the specific affinity between folic acid and the folic acid receptor,as a model analyte hindered the electron donor from reaching the electrode surface,decreasing the PEC response.This proposed photoelectrochemical cytosensing platform exhibited good performance for assay of tumor cells with overexpress receptors on cells.Secondly,a new PEC cytosensor was constructed by using cationic polyfluorene derivative,poly(9,9-bis(6'-N,N,N,-trimethylammonium)hexyl)fluorene-co-alt-1,4-phenylene)bromide)(PFP)as the photoelectric-responsive material for sensitive cell detection.Positive-charged PFP with high photoelectric conversion efficiency can generate robust photocurrent under the light illumination.In the PEC cytosensor,the 3-phosphonopropionic acid was linked to the ITO electrode followed by the modification with anti-EpCAM(epithelial-cell-adhesion-molecule)antibody via amide condensation reaction.Thus,target SKBR-3 cells with overexpressed EpCAM antigen could be captured onto the electrode via the specific antibody-antigen interactions.Upon adding cationic PFP,a favorable electrostatic interaction between cationic PFP and negatively charged cell membrane led to a turn-on detection signal for target SKBR-3 cells.This new cytosensor not only exhibits good sensitivity because of the good photoelectric performance of conjugated polymers,but also offers decent selectivity to target cells by taking advantage of the specific antibody-antigen recognition.Thirdly,a novel ultrasensitive PEC microRNAs(miRNAs)biosensing strategy was established based on the robust photocurrent generated by TiO2/Au nanoparticles(AuNPs)composite.Au NPs,acted as a plasmonic photosensitizer,could extend the photo-conversion wavelength to visible region,which increased the photocurrent intensity.After introducing the CdS QDs,the plasmonic Au NPs acted as an electron relay could accelerated the charge transfer between CdS QDs and TiO2 nanorod.Moreover,the efficient energy transfer also promoted more electron-hole pairs in TiO2/AuNPs composite.The dual role of AuNPs dramatically increased the photocurrent compared with single TiO2 nanorod,which guaranteed enough sensitivity for the miRNAs biosensor.In the presence of the target miRNA-122,CdS QDs would separate from TiO2/AuNPs composite,resulting in the decrease of photocurrent.A novel signal-off biosensor was constructed based on the proportional relationship between photocurrent intensity and the concentration of target miRNA-122.This proposed detecting platform exhibited wide linear range,low detection limit and good sensitivity,indicating promising prospects for early clinical diagnoses of cancer.The employment of physical light source in clinical photodynamic therapy(PDT)system endow it with crucial defect in the treatment of deeper tissue lesions due to the limited penetration depth of light in biological tissues.In the fourth work,we constructed for the first time an electric driven luminous system based on electrochemiluminescence(ECL)for killing pathogenic bacteria,where ECL is used for the excitation of photosensitizer instead of physical light source to produce reactive oxygen species(ROS).We named this new strategy as ECL-therapeutics.The perfect spectral overlap guarantees the energy transfer from the ECL generated by luminol to photosensitizer,cationic oligo(p-phenylene vinylene)(OPV),which could sensitize the surrounding oxygen molecule into ROS and kill pathogenic bacteria.This new strategy exhibits good germicidal efficacy,which exploits new field for ECL beyond sensors and also opens up a new model for PDT.Lastly,we used flexible polyacrylamide hydrogel replace the liquid system as substrate to loading chemical to develop hydrogel antibacterial device.We employ the simple AC power to replace the traditional electric chemiluminescence workstation to provide electric energy.The ECL of luminol activates photosensitizer cationic oligomers OPV to produce reactive oxygen species and then achieve the purpose of sterilization.Because the chemical reaction is a slow process in the hydrogel,the luminescence could last for more than ten minutes after only electrifying for five seconds.This unique persistent luminescence characteristic with long afterglow life makes them suitable for persistent antibacterial applications.This stretchable hydrogel device provides a unique pattern of short charge and persistent antibacterial activity.