Sensing System Based On Gold Nanoparticles For Charge Neutralization Aggregation And Catalytic Tb³⁺/Eu³⁺luminescence

Due to its special optical properties,high catalytic properties,electrical properties and good biocompatibility,Au NPs has become one of the most popular nanomaterials at home and abroad.Based on the unique surface plasmon resonance effect,high catalytic activity and the diversity of signal characterization pathways,Au NPs has been widely used in biological colorimetric sensing and catalysis to detect nucleic acids,metal ions and other targets.Nucleic acid molecules have become genetically important research objects in biomedicine because they carry genetic information and are closely related to life activities such as growth,development,reproduction and canceration of organisms.Rare earth elements play an important role in the progress of science and technology and the development of industry because of their unique spectral properties.In this work,the special optical properties and high catalytic activity of gold nanoparticles are combined with the latest sensing analysis technology to target nucleic acids and rare earth ions as the target analytes to construct a highly sensitive new nano-gold sensing probe analysis method.It mainly includes the following two research sections:???Based on nucleic acid dyes to induce rapid accumulation of gold nanoparticles,a new colorimetric sensing method for DNA detection by gold nanoparticles label-free was developed.Aggregation of plasmonic gold nanoparticles?Au NPs?has been widely used for label-free colorimetric sensing.Adding salt is a commonly used method to induce a color change,but salt-induced aggregation by charge screening is a slow kinetic process,making quantitative and reproducible measurement difficult.Herein,we explored an alternative method by charge neutralization using positively charged molecules,such as a DNA-staining dye,SYBR Green I?SG?,for efficient and stable assembly of Au NPs.The charge neutralization effect of SG was confirmed with zeta potential measurements.The SG-induced assembly of Au NPs was developed into a label-free colorimetric sensing platform.Positively charged nucleic acid dyes can be embedded in the grooves of ds DNA to prevent them from interacting with Au NPs.Based on the formation or dissociation of ds DNA,the regulation of nano-gold aggregation can be used for DNA detection.Benefiting from the intense blue color,this new sensing strategy allowed visual detection of as low as 0.1 n M DNA,50-fold lower than that by salt.This work itself significantly improved Au NP-based colorimetric sensors in terms of detection time,signal stability,and sensitivity.The method is simple to operate,no need to separate,labeling and other steps,and can be extended to the detection of other arbitrary sequence DNA,which has a good application prospect.???A sensing method based on Na IO₄-H₂O₂-Au NPs chemiluminescence system for detecting rare earth ions was developed.Catalysis is one of the simple and effective means to achieve high-sensitivity analysis and has been widely used in biological analysis,environmental analysis and other fields.We found that nano-gold has a catalytic activity comparable to horseradish peroxidase in the Na IO₄-H₂O₂ chemiluminescence system,thereby establishing a nano-gold catalytic-rare-earth chemiluminescence sensing platform.The luminescence mechanism of the system was verified by free radical scavenger and free radical trapping agent,and it was proved that the redox reaction between Na IO₄ and H₂O₂produced reactive oxygen species 1O₂ and·OH,and the characteristic chemiluminescence spectrum was emitted by energy transfer to rare earth ions through ligand EDTA.The influences of different ligands on the system were also investigated,and the concentrations of system ligands,H₂O₂ and Na IO₄ were optimized.Under the optimal conditions,chemiluminescence detection using filters with specific wavelengths has enabled the simultaneous detection of europium and europium ions,with detection limits of 5.0 n M and 0.8?M,respectively.This method has the advantages of high sensitivity,simple and fast instrument operation,no background interference such as light scattering,and can realize multi-component detection.It provides new ideas for the diversified development of the detection platform for analysts.