Study On Electrochemiluminescent Biosensors Based On Nanomaterials

Electrochemiluminescence?ECL?is the process whereby species generated at electrodes undergo high-energy electron-transfer reactions to form excited states that emit light.It is a new technology combined with electrochemical and chemiluminescence.It has become a useful technology in basic research and analytical application because of its high sensitivity,wide linear range,low background signal and good selectivity.Nano-materials have been widely used in the construction of biosensors because of their excellent biocompatibility,optical and electrochemical properties.In this paper,a series of highly sensitive electrochemiluminescence biosensors were constructed by using novel nanomaterials and their composites,and their applications in biological applications were discussed.The main contents are as follows:1.An ultrasensitive electrochemiluminescence DNA-based biosensor that employs steric hindrance effects to detect Human IgGA highly selective DNA-based electrochemiluminescence?ECL?biosensor was developed for the detection of Human IgG?IgG?that take advantage of steric hindrance effects to influence of the ECL signal at the presence of target protein.In this assay,Digxin-linked signaling DNA was specifically bound to the target protein IgG with strong affinity in the presence of IgG,generating steric hindrance effects,which limited the ability of this DNA to hybridize with capturing DNA strand attached on the surface of a gold electrode,leading to lower ECL siganl.Using this steric hindrance hybridization assay in an ECL format under the optimum conditions,the ECL signals of biosensor were proportional to the concentration of IgG in a wide linear range and a low detection limit.This unique detection method simplifies the process,shorten the time,improve the detection sensitivity.2.A novel electrochemiluminescence biosensor for the detection of microRNAs based on a DNA functionalized nitrogen doped carbon quantum dots as signal enhancersIn this paper,nitrogen doped carbon quantum dots?N-CQDs?were synthesized by microwave-assisted hydrothermal method.The quantum dots with smaller particle size and good optical properties.Based on N-C QDs as a biomarker for signal and combined with the endonuclease?Nb.BbvCI?mediated signal amplification?NESA?,a ultrasensitive biosensor was built for detection of microRNA.First,the hairpin probel-QDs?HP1?with assistant probe and microRNA?miRNA?formed Y junction structure which was cleaved with the addition of nicking enzymes Nb.BbvCI to release miRNA and assistant probe.Subsequently,the released miRNA and assistant probe could initiate the next recycling process,leading to the generation of numerous intermediate sequences N-CQDs-DNA?S1?,which can hybridize with hairpin probe2?HP2?immobilized on GO/Au composite modified GCE surface for ECL signal enhancing by N-CQDs.Therefore,the ECL intensity will increase with the increasing concentration of microRNA,with a linear range of 10 aM-104 fM and a lower detection limit for 10 aM,and this biosensor display high specificity and good reproducibility.3.Label-free electrochemiluminescence aptasensor for highly sensitive detection of acetylcholinesterase based on Au nanoparticles functionalized g-C₃N₄ nanohybridA feasible label-free electrochemiluminescence?ECL?aptasensor using Au nanoparticles functionalized g-C₃N₄ nanohybrid?Au-g-C₃N₄ NH?as luminophore was constructed for highly sensitive acetylcholinesterase?AChE?detection.The sensor was fabricated by successively modifying a glassy carbon electrode?GCE?with Au-g-C₃N₄ NH and thiol-modified AChE-specific aptamers.In the presence of AChE,the ECL signal decreased significantly because ACNE could hydrolyze the substrate acetylthiocholine?ATCl?to generate acetic acid?HAc?which could react with the coreactant triethylamine?Et3N?,leading to evident consumption of the coreactant.The ECL response of the aptasensor was linearly proportional to the concentration of AChE ranging from 0.1 pg/mL to 10 ng/mL,with a detection limit of 42.3 fg/mL?S/N=3?.This novel ECL sensing strategy demonstrated a highly sensitive and selective method for AChE detection and was expected to possess potential applications in clinical diagnosis and biomedical technology.