Study On High Sensitive Photoelectrochemical Immunoassay Based On Functionalized Liposome

As an important direction of photochemical(PEC)bioanalysis,PEC immunoassay is a new analysis detection method based on the photoelectric conversion of photoactive materials.PEC immunoassay is an effective integration of PEC analysis and specific immune response,which has some advantages,including simple operation,easy miniaturization and high sensitivity.Due to the above fascinated characteristic,PEC immunoassay has attaracted extensive research interest.Currently,PEC immunoassay has made some progress,and a variety of advanced PEC immunoassay have been developed for different targets.The continuous development of life analysis science also puts forward higher requirements for the existing PEC immunoassay methods.The development of a new signal amplification strategy is of great significance to realize the sensitive analysis of various small molecules.As the carrier of signal molecules,liposomes can convert one-to-one biorecognition events into one-to-many signal output events,which can realize the effective amplification of signals.Thus,three functionalized liposome PEC immunoassay protocols have been developed as follows:1.Enediol-Ligands-Encapsulated Liposomes Enables Sensitive Immunoassay:A Proof-of-Concept for General Liposomes-Based Photoelectrochemical ImmunoassaySensitive photoelectrochemical(PEC)bioanalysis usually relies on enzyme-assisted signal amplification.This chapter describes the first proof-of-concept study for liposome-based PEC bioanalysis.Specifically,unilamellar liposomes were prepared and then utilized to carry the enediol-ligands and antibodies within their internal cavities and upon their external surfaces,respectively.On the other hand,the 96-well plate was used for accommodating the sandwich immunocomplexing,and then the confined liposomes were directed to release the encapsulated enediol-ligands into an individual well.The subsequent in situ sensitization of the TiO2 nanoparticles(NPs)electrode was then used to transduce the recognition events.This facile strategy allows for sensitive immunoassay without the involvement of laborious electrode fabrication and enzymatic amplification.Importantly,the protocol can be extended as a general PEC method for numerous other targets of interest.We believe this work could offer a new perspective for the rational implementation of various liposome complexes for novel PEC bioanalysis2.Cu Nanoclusters-Encapsulated Liposomes:Toward Sensitive Liposomal Photoelectrochemical ImmunoassayIn the third chapter,we have proposed the strategy of liposome mediated Cu2+-induced exciton trapping upon CdS quantum dots(QDs)for amplified PEC immunoassay application.Specifically,the Cu nanoclusters(NCs)-encapsulated liposomes were first fabricated and then processed with antibodies bound to their external surfaces.After the sandwich immunocomplexing,the confined liposomal labels were subjected to sequential lysis treatments for the release of Cu NCs and numerous Cu2+ions,which were then directed to interact with the CdS QDs electrode.The interaction of Cu2+ions with CdS QDs could generate CuxS and form the trapping sites to block the photocurrent generation.Since the photocurrent inhibition is closely related with the Cu NCs-loaded liposomal labels,a novel and general"signal-off" PEC immunoassay could thus be tailored with high sensitivity.Meanwhile,a complementary "signal-on" fluorescent detection could be accomplished by measuring the fluorescence intensity originated from the Cu NCs.This work features the first use of Cu NCs in PEC immunoassay and also the first NCs-loaded liposomal PEC immunoassay.More importantly,by using other specific ions/reagents-semiconductors interactions,this protocol could serve as a common basis for the general development of a new class of liposome-mediated PEC immunoassay.3.Liposome-Mediated in Situ Formation of AgI/Ag/BiOI Z-Scheme Heterojunction on Foamed Nickel Electrode:A Proof-of-Concept Study for Cathodic Liposomal Photoelectrochemical BioanalysisIn the forth chapter,we have reported the liposome-mediated in situ formation of the AgI/Ag/BiOI Z-scheme heterojunction on foamed nickel electrode for signal-on cathodic PEC immunoassay.Specifically,in a proof-of concept study,Ag NPs encapsulated liposomes were initially confined via the sandwich immunobinding and then processed to release numerous Ag+ions,which were then directed to react with the BiOI/Ni electrode,resulting in the in situ generation of a Agl/Ag/BiOI Z-scheme heterojunction on the electrode.The enhanced cathodic signal could be correlated to the target concentration,which thus underlays a novel signal-on cathodic liposomal PEC immunoassay strategy.Diferent from previous anodic liposomal PEC immunoassay,this work features the first cathodic liposomal PEC immunoassay on the basis of the in situ formation of a Z-scheme heterojunction.More generally,integrated with various biorecognition events,this protocol could serve as a common basis for addressing numerous targets of interest.4.A Polymer Quantum Dots Liposomes Based Photoelectrochemical Cell Sensor:High-Efficient Analysis of Surface protein expression of Cancer cellsIn the fifth chapter,we have developed a cathodic PEC cell sensor based on polymer quantum dot liposome(PDLL),which could be used for the ultrasensitive detection of MCF-7 cell surface protein.The PDLL labeled sandwich immune complex was constructed in 96-well plates.The concentration of target is proportional to the amount of polymer quantum dots(Pdots)encapsulated liposomes,so the standard curve of CEA concentration have been made based on the measurement of the photocurrent change.The developed PEC immunoassay has been also used to measure the MCF-7 cell surface protein under the same experimental conditions.On the basis of this novel protocol,signal amplification was ingeniously introduced into the PEC cell sensor,resulting in ultrasensitive quantification of MCF-7 cells surface CEA.Benefting from the fascinating analytical performance of the developed liposomal PEC sensor,ultralow expression of antigens for MCF-7 was discriminated effectively.