Novel Electrochemiluminescence Approaches For Prostate Cancer-related Gene And Protein

Electrochemiluminescence(ECL)technique has been widely used in biosensing with the advantages of low cost,wide range of analytes,low background signal,and high sensitivity.Because of the amounts of some proteins and microRNAs are usually low in the biological body,the development of highly sensitive analytical methods is highly desirable.This doctoral dissertation focuses on developing ECL biosensors based on signal amplification and resonance energy transfer technic for cancer biomarker and microRNAs detection.1.Nanopore-Based Electrochemiluminescence for Detection of microRNAs via Duplex-Specific Nuclease-Assisted Target RecyclingIn this study,we proposed a nanopore-based ECL sensor combined with DuplexSpecific Nuclease(DSN)-assisted target recycling amplification to detect microRNAs.Due to the synergetic effect of electrostatic repulsion and volume exclusion of gold nanoparticle-labeled DNA capture(DNA-Au NPs)to negatively charged luminol anion probe,the DNA-Au NPs modified anodized aluminium oxide(AAO)nanopores electrode exhibited high ECL decline in comparison to bare AAO electrode.Upon the introduction of DSN enzyme and target microRNA,the specific DNA-RNA binding and enzyme cleaving could trigger the detachment of capture DNA from the membrane surface,resulting in uncapping of AAO and an increased ECL signal.For comparsion,positively charged Ru(bpy)32+was used as ECL probe instead of luminol.Because the electrostatic attraction effect between DNA and Ru(bpy)32+is partially offset by the volume exclusion effect of Au NPs,AAO electrode only modified with DNA capture is more suitable for Ru(bpy)32+ case.In our experiment,the case of negatively charged luminol combined with the synergetic effect of electrostatic repulsion and volume exclusion of DNA-Au NPs provides a quantitative readout proportional to the target microRNAs concentration in the range of 1.0 fM to 1.0 nM with a lower detection limit(LOD)of 1 fM.2.Electrochemiluminescence Resonance Energy Transfer System for DualWavelength Ratiometric microRNA DetectionElectrochemiluminescence resonance energy transfer(ECL-RET)technique has been extensively used for biosensing with the advantages of high sensitivity,low background signal,low cost,and wide range of analytes.Compared to single-signal measurement,the dual-wavelength ratiometric ECL system relies on the ratio of ECL intensities at two wavelengths,which is an ideal choice to reduce the falsepositive or negative signals and makes the detection more convincing.To construct a highly sensitive dual-wavelength ECL-RET ratiometric system,a perfect energy overlapped pair of donor-acceptor with strong ECL emission of donors and high quantum yield of the acceptor is needed.In this study,combining with DSN-assisted target recycling amplification,we proposed a dual wavelength of ECL-RET ratiometric sensor with strong ECL emission of L-LDH and high quantum yield of Au NCs as donor-acceptor to sensitively detect target microRNAs.Due to the high ECL-RET efficiency of donor-acceptor and DSN-assisted target recycling amplification,the designed sensor provides a quantitative readout proportional to the target microRNAs concentration in the range of 10 aM to 100 pM with a low detection limit down to 9.4 aM.This designed ECL sensor has a high sensitivity and selectivity for microRNA detection,providing a great promise in clinical diagnosis.3.Multi-Segmented CdS-Au Nanorod for Electrochemiluminescence BioanalysisIn SPR-enhanced fluorescence study,it has been commonly accepted that the increased excitation and radiative decay rate,which is the result of the enhancement of electromagnetic field,are contributed to the fluorescence enhancement.Unlike the fluorescence,the excitation source of SPR of plasmonic nanoparticles is come from the light generated by electrochemical reaction in electrochemiluminescence(ECL),the influence of electron transfer to electromagnetic field of SPR should be considered.To provide some basis in this area,we developed a programmable ECL system based on multi-segmented CdS-Au nanorod arrays.This unique nanostructure is synthesized by an electrodeposition method.In that way,the CdS segments and Au segments could be electrodeposited at the sequence and the length can be specifically designed.We shed light on that the better ECL performance of multi-segmented CdS-Au nanorod arrays is a result of the favorable electron transfer combined with the SPR effect of Au segment,comparing to pure CdS nanorod arrays.This study provides some basis for designing high-performance ECL emission materials.Using the multi-segmented CdS-Au nanorod arrays as ECL emission material,a sensor was successfully constructed to detect prostate specific antigen(PSA).4.Multiple Amplified Electrogenerated Chemiluminescence Immunosensor Based on Poly-L-Glutamic AcidIn this work,On the basis of the ECL signal of Au NPs-L-LDH,an ECL sandwich immunosensor for sensitive detection of cancer biomarkers was developed with a signal am plification strategy by enhanced precipitation using glucose oxidase(GOx)and Pt NPs attached on Poly-L-Glutamic Acid.In this sensor,PGA could carry numerous GOx which can catalyze dissolved oxygen and glucose to produce hydrogen peroxide.Pt NPs can greatly improve the ECL signals by catalyzing electrochemical reactions associated with the luminol ECL process.The as-proposed ECL immunosensor exhibited high sensitivity and specificity on the detection of PSA.A linear relationship between ECL signals and the concentrations of PSA was obtained in the range from 1.0 pg/mL to 150 ng/mL.The detection limit of 0.6 pg/mL(signal-to-noise ratio of 3)was obtained.Moreover,the as proposed ECL immunosensor exhibited excellent stability and selectivity.The results suggest that the as-proposed ECL immunosensor will be promising in the diagnostics application of clinical screening of cancer biomarkers.