Aggregation-induced Luminescent Organic Fluorescent Probes And Novel ZnO/CdS Nanophotovoltaic Materials Were Used For Biosensor Construction

In recent years,biosensors have broad application prospects in life sciences,disease diagnosis and treatment,food safety and so on,and are the forefront of analytical chemistry.Biosensor can replace the traditional and time-consuming bio-analysis methods of traditional laboratories.It has the advantages of good selectivity,high sensitivity and fast,in situ,miniaturization and low cost.It provides an effective means for life science research.Firstly,the research of nanomaterials has developed rapidly.The emergence of new functionalized nanomaterials has the advantages of high specific surface area,high electrical conductivity and strong mechanical properties.It also has the advantages of high catalytic activity,high adsorption capacity,Good compatibility,etc.,in the biological signal recognition,detection more and more show an important role,and for the construction of high selectivity,high sensitivity,fast and efficient biosensor provides a new design ideas.In addition,fluorescence detection technology has many advantages such as high sensitivity,low noise and wide dynamic range.The molecules with AIE properties do not undergo fluorescence quenching in the aggregation state,and the fluorescence spectra of most AIE molecules do not Concentration changes occur,AIE fluorescent probe is used in a turn-on mechanism,the sensitivity is relatively high.SiO₂-AIE has good biocompatibility,excellent chemical inertness,stable optical properties,high luminous intensity.In biomedical engineering,electronics,catalytic engineering has been widely used.Based on a large number of literatures,this paper focuses on the synthesis of luminescence and the synthesis of new optoelectronic nanomaterials,which are based on the application of aggregation-induced luminescence phenomena and functionalized nanomaterials in electrochemical,photochemical and biosensor.Biosensor detection of biomarkers.The main work is as follows:?1?We developed an AIE-SiO₂ NPs based label-free fluorescent assay for highly selective and sensitive “turn-on” sensing of GSH with the aid of MnO₂ nanosheets.The AIE-SiO₂ NPs design could avoid the notorious ACQ effect and sophisticated fluorophore labeling process of fluorescent probe.Besides,the MnO₂ nanosheets were employed as both positive charge protectors for amino-functionalized SiO₂ NPs to form MnO₂-SiO₂ NPs nanocomposite and specific recognition units for GSH.Moreover,the proposed sensing system was further applied in human serum samples for the detection of GSH with satisfactory results,demonstrating its promising application in practical biological samples.The simplicity in operation and instrumentation of this method made it more convenient and more readily adopted by other biotargets.?2?An AIE-SiO₂ NPs based fluorescent aptasensor for the sensitive detection of PSA is developed herein for the first time.The positively charged amino-functionalized SiO₂ NPs with good water dispersibility can be easily synthesized and used as an efficient nanocapturer.SiO₂ NPs-PA composite was formed by electrostatically adsorbed single-stranded PSA aptamer probes and AIE-SiO₂ NPs composite was obtained by adsorbing negatively charged AIE molecule TPE3.The binding of the PA to the target PSA could induce a rigid aptamer conformation,which would result in the release of the PA away from the surface of SiO₂ NPs.This made the negatively charged TPE3 aggregate on the SiO₂ NPs surface and emit high fluorescence.The proposed label-free aptasensor showed a “turn-on” fluorescent response to PSA with a high sensitivity and a detection limit of 0.1 ng/m L was achieved.The proposed aptasensor was further applied in human serum samples for the detection of PSA with satisfactory results,demonstrating its promising application in practical biological samples.?3?A novel photoelectrochemical biosensing platform was constructed via the combined strategy of both photoelectrochemcial analysis and bioetching.The tremella-like ZnO-Au@CdS nanospheres were obtained by depositing Au nanoparticles?NPs?and CdS NPs on the surface of ZnO microspheres.The introduction of intermediate electrotransfer of Au NPs to isolated ZnO and CdS systems significantly enhanced the photoelectrochemical property.CdS NPs could be irreversibly bioetched by an enzymatic reaction catalyzed by horseradish peroxidase?HRP?and H2O₂.As a result,the detection of H2O₂ could be realized based on the decrease of the intensity of the photoelectrochemical signal.This interference free sensing platform had the linear range from 0.15 to 100??M with a detection limit of 0.14 ?M H2O₂ at S/N = 3.Furthermore,glucose oxidase?GOD?was successfully immobilized on ZnO-Au@CdS nanospheres to construct a glucose biosensor.The excellent results were obtained with a detection limit of 0.50 ?M at S/N = 3.The photoelectrochemical biosensor showed a good performance with lower detection limit,good stability and accuracy,strong anti-interference,showing a promising application in photoelectrochemical biosensing.?4?We describe the fabrication of ZnO/CdS@ZIF-8 core-shell nanostructures to enhance the intrinsic catalytic performance of ZnO/CdS semiconductor heterojunction.The synthesis was conducted using CdS NPs-anchored spindle-like ZnO NPs as seeds to direct the heterogeneous growth of ZIF-8 and thus the formation of ZIF-8 shell.The synthetic strategy has three following advantages: i)Zn O/CdS seeds could serve as nucleation location for heterogeneous nucleation,which thus effectively eliminate the homogeneous nucleation and growth of ZIF materials that normally unvoided in the synthesis of ZIF-based core-shell product;ii)ZnO in the seeds could provide Zn2+ during the formation of ZIF-8 and thus no more Zn precursor needs to be added in the growth step;iii)unlike previous report using ZnO nanowire array as the starting material to fabricate semiconductor@ZIF core-shell structure,the current work employs free-standing spindle-like ZnO/CdS NPs as seeds,which makes the catalyst much easier to suspend in the reaction system and interact with reactants.A set of characterizations were performed to study their size,shape,structure,and composition.Interestingly,the as-prepared ZnO/CdS@ZIF-8 exhibited great distinct photocatalytic efficiency in degradation of organic pollutant due to the synergetic function of semiconductor heterojunction and ZIF material.