| As a new yet actively developing technique,photoelectrochemical(PEC)has attracted considerable interest in various fields including environmental monitoring,food security,especially bioanalysis.Due to its desirable advantages such as high sensitivity,fast respond,low-cost and simple instrumentation,enormous efforts have been devoted to its study and significant progress has been made for DNA detection,immunoassay,as well as cell-related analysis.On the other side,photocatalytic nanostructured materials also play important roles in PEC bioanalytical science in the past decade.Among various nanomaterials,TiO2 is one of the most extensively studied nanostructured oxides and possesses unique characteristics including large strength-to-weight ratio,high catalytic efficiency,excellent photochemical stability and biocompatibility in PEC applications.In this thesis,through the design of novel PEC platforms for exploitation of ingenious signaling mechanism,we have fabricated innovative PEC devices to realize immunoassay and cell-related analysis.The main works are described as follows:1.Photoelectrochemical Probing of Cellular Interfaces and Evaluation of Cellular H2S Production Based on In Situ-Generated CdS-Enhanced TiO2 Nanotube HeterostructuresThe first work reports the novel photoelectrochemical(PEC)probing of cellular interfaces and the evaluation of cellular H2S production based on in situ-generated.CdS-enhanced TiO2 nanotube(NT)heterostructures.We chose the TiO2 NT array in particular,owing to its structure of regular oriented vertical NTs(which permits fast directional charge transport)and its substantial inner cavity(which guarantees the highly efficient guest loading and molecule capture).HepG2 cells directly grown on and interfacing with the the as-obtained Cd2+/TiO2 NTs electrodes.H2S could be released from HepG2 cells by the stimulation of appropriate drugs and then CdS generated in situ on the TiO2,NTs.Owing to the aforementioned unique properties of TiO2 NTs,even small amounts of in situ-generated CdS could be detected and result in apparent electrical signals.To the best of our knowledge,such TiO2 NT-based in situ PEC probing of cellular interfaces and evaluation of H2S cellular production have not previously been reported2.Alkaline Phosphatase Tagged Antibodies on Gold Nanoparticles/TiO2 Nanotubes Electrode:A Plasmonic Strategy for Label-free and Amplified Photoelectrochemical ImmunoassayThis work reports a plasmonic strategy capable of label-free yet amplified photoelectrochemical(PEC)immunoassay for the sensitive and specific detection of model protein p53,an important transcription factor that regulates the cell cycle and functions as a tumor suppressor.Specifically,on basis of Au nanoparticles(NPs)deposited on hierarchically ordered TiO2 nanotubes(NTs),a protein G molecular membrane was used for immobilization of alkaline phosphatase(ALP)conjugated anti-p53(ALP-a-p53).Due to the immunological recognition between the receptor and target.the plasmonic charge separation from Au NPs to the conduction band of TiO2 NTs could be influenced greatly that originated from signal amplification.The degree of signal suppression is directly associated with the target concentration,so by monitoring the changes of the plasmonic photocurrent responding after the specific binding,a new plasmonic PEC immunoassay could be tailored for label-free and amplified detection.This approach could sensitively detect the concentration of target p53 in a wide range from 0.05 ng mL-1 to 100 ng mL-1.The operating principle of this study could be extended as a general protocol for numerous other targets of interest. |
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