Study On The Electrochemiluminescence Of Functionalized Perylene Compounds And Its Application In Biosensor Analysis

Electrochemiluminescence(ECL)techniques,which combined the advantages of spectral analysis and electrochemical analysis,have witnessed significant progress in the biosensing field because of the promises offered by the simple instrumentation required,high sensitivity,low background signal,and wide dynamic concentration response range.Current luminophores were more likely to focus on metal complexes,luminol,quantum dots,and metal nanocluster.However,these ECL luminophores show some deficiency,such as high-cost and complicated preparation procedure.Perylene compounds with large ?-conjugated system could be used as a very promising ECL materials because of their high photoluminescence quantum yield,good physical and chemical stability and outstanding photoelectron properties.In addition,perylene compounds was easy to chemically modify with a variety of functional groups,and thus making it possessing a unique physiochemical properties.Accordingly,this thesis mainly studies the ECL mechanism of functionalized perylene compounds,and further combines the DNA-based signal amplification and nanomaterial-based signal amplification strategies to construct a variety of ECL biosensors for the detection of heavy metal ions.The studies of this thesis are mainly divided into the following sections:Part 1 The research on ratiometric type of lead ion sensor based on electrochemiluminescence resonance energy transfer system.Usually,ECL analysis was based on the single signal intensity to determine the concentration of analytes.However,in practical applications,the single signal was affected by many factors,such as the stability of the light source,the microenvironment of the substrate solution(polarity,temperature and pH)and the sensitivity of the instrument,etc.The ratiometric analysis was based on the change of the signal intensity ratio at two different wavelengths,which could decrease false positives or false negatives and makes the detection results more accurate.In this study,a ratiometric aptasensor,based on the electrochemiluminescence resonance energy transfer(ECL-RET)system between amino-terminated perylene derivative/peroxydisulfate(PTC-NH2/S2O82-)and O2/S2O82-,was successfully constructed for determination of heavy lead ion(Pb2+).In this study,the target Pb2+ induced the generation of the Pb2+G-quadruplex structure to control the amount of PTC-NH2,which further caused achange in the peak intensity ratio of the PTC-NH2/S2O82-at-0.7 V and O2/S2O82-at-2.0V.By measuring the ratio of ECL intensities at two excitation potentials,the developed ratiometric aptasensor exhibited the linear response range from 1.0×10-12 mol/L to1.0×10-7 mol/L with a detection limit of 3.5×10-13 mol/L for Pb2+.Part 2 The research on “on-off-on” type of copper ion sensor based on supramolecular nanorods as electroluminescent materials.Considering of the traditional ECL materials(such as metal complexes,luminol,quantum dots and metal nanoclusters)possess the characteristics,such as high cost,complicated preparation process,difficult structure modification and difficult loading.Thus,it is imperative to explore new ECL materials to overcome these shortcomings.In recent years,3,4,9,10-perylene tetracarboxylic acid(PTCA)has its unique advantages(such as higher fluorescence quantum yield,low cost,excellent electron transport properties and structure easy to modify,etc.),and thus making it being a very promising ECL materials.In this study,a novel supramolecular nanorods(PTCA-An)were prepared by the supramolecular force of PTCA and aniline(An),which could not only be used as biosensor interface materials possessing a large specific surface area and excellent conductivity and good film-forming properties,but also be used as a new ECL material providing a strong and stable ECL signal via the co-reaction promoter(An)amplification.Therefore,based on the high quenching effect of aminated ferrocene(Fc-NH2)on the excited state PTCA(1PTCA*),an “on-off-on” biosensor was constructed for heavy metal copper ions(Cu2+)detection.In the presence of Cu2+,the Cu2+-specific DNAzyme was irreversibly cleaved resulting in the release of the quencher probes from sensing interface.As a result,on the basis of the ECL intensities changes before and after incubating with the target Cu2+,the prepared Cu2+-specific DNAzyme-based biosensor showed the linear response range from 1.0×10-12 mol/L to1.0×10-7 mol/L with a detection limit of 3.4×10-13 mol/L for Cu2+.Part 3 The research on electrochemiluminescence copper ion nanosensor based on multifunctionalized cobalt ferrite magnetic nanoparticles.Generally,ECL biosensors based on the heterogeneous-based assay formats(e.g.,the modified gold electrode or glassy carbon electrode surface as the reaction interface)often accompanied by some intrinsic disadvantages:(1)the limited reaction area and the existence of local steric hindrance lead to relatively slow binding kinetics and low binding efficiency of recognition probes,which further impacted the sensitivity and selectivity of the analysis.(2)the fouling of the electrode lead to relatively low reproducibility.However,the magnetic nanocarriers in the quasi-homogeneous system,which could not only expand the reaction area and improve the steric hindrance as a "bridge" between the aqueous phase and the solid phase due to its large specific surface area,but also allow the reaction product to be quickly and conveniently separated from the complex sample solution by virtue of its excellent magnetic properties.In this study,a multifunctionalized cobalt ferrite(CoFe2O4)-based magnetic nanosensors with the dual amplified strategies of co-reaction accelerator amplification and hybridization chain reaction amplification,have been designed for ultra-sensitive ECL detection of copper ion(Cu2+).In addition,cobalt ferrite(CoFe2O4)magnetic nanoparticles could act as a new co-reaction accelerator in ECL binary(PTC-NH2/S2O82-)system,which could significantly enhance the ECL efficiency of PTC-NH2.As a result,the prepared magnetic nanosensors were applied for the determination of Cu2+ with a linear detection range from 10-13 mol/L to 1.0×10-7 mol/L with a detection limit of 3.4×10-14 mol/L for Cu2+.