Preparation Of SiO₂-core Quantum Dot Nanoparticles And Their Application In Lateral Flow Immunosensing

Quantum dot（QD）is a semiconductor nanomaterial with the advantages of high quantum efficiency,wide absorption spectrum and narrow emission spectrum,which is a good candidate for biochemical analysis.Recently,the construction of quantum dot nanoparticles by embedding quantum dots in polymer molecules has become a research focus.Compared with ordinary quantum dots,these quantum dot nanoparticles provide stronger fluorescence properties,further yielding a higher sensitivity and stability,and has been widely applied to detect toxins,viruses,biomarkers.In this research,a method for the preparation of high performance silica-core quantum dot nanoparticles is reported.Firstly,silica-core@quantum dot nanoparticles（SiO₂@QD）were prepared by electrostatic adsorption of polyethyleneimine（PEI）.Next,silica-core@multilayer quantum dot nanoparticles were prepared using PEI-mediated layer-by-layer self-assembly method.Finally,a novel method of fluorescence lateral flow immunoassay（LFA）was established using silica-core@quantum dot nanoparticles as a label to achieve rapid and highly sensitive quantitative detection of the analytes.The main conclusions are as follows:（1）The silica-core@quantum dot nanoparticles were characterized by TEM,SEM and fluorescence spectroscopy instruments.The results showed that silica-core@quantum dot nanoparticles have the advantages of uniform particle size,good stability and good dispersion.Compared with ordinary quantum dots,the fluorescence signal of silica-core@quantum dot nanoparticles is significantly enhanced.When silica-core@quantum dot nanoparticles were used as fluorescent labels for LFA,they have the advantages of high sensitivity and stable fluorescent signal,and are suitable for multi-channel immunoassay quantitative detection.（2）A method is reported based on dual-color SiO₂@quantum dot（SiO₂@QD525/SiO₂@QD625）–integrated lateral flow immunoassay strip to realize the quantitative and simultaneous detection of C-reactive protein（CRP）and procalcitonin（PCT）in serum.The results showed that the SiO₂@QD-based LFA has high sensitivity,stability and specificity,and the limits of detection（LODs）of CRP and PCT reached 0.5and 0.05 ng/m L,respectively,which were 20 and 100 times higher than those of colloidal gold LFA.In conclusion,the SiO₂@QD-based LFA has the ability of rapid,sensitive and quantitative detection.（3）A strategy is proposed based on spike protein-conjugated silica–core@dual quantum dot（SiO₂@DQD）-integrated LFA strip to simultaneously detect SARS-Co V-2-specific Ig M and Ig G in clinical samples.And the sensitivity,specificity,reproducibility were performed.The results indicate that the SiO₂@DQD-based LFA has excellent stability,sensitivity and specificity.（4）A sensitive and quantitative silica–core@triple quantum dot（SiO₂@TQD）-based LFA strip for simultaneous detection of influenza A（H1N1）virus and SARS-Co V-2 is proposed.The limits of detection（LODs）of H1N1 and SARS-Co V-2 reached 50 pfu/m L and 0.005 ng/m L,respectively,and had good specificity and stability.Compared with commercial ELISA kits,the detection sensitivity was increased by 100 and 20 times,respectively.It demonstrates the SiO₂@TQD-based LFA has the ability of rapid,ultrasensitive and quantitative detection.