Prepartion And Immunoassay Application Of Multi-mode Optical Probes Based On Rod-like Silica Nanocomposites

Nanobioassay technology has important applications in food safety,disease diagnosis,environmental surveillance and other fields.However,the traditional single-mode nano-biological detection technology faced bottlenecks,such as the insufficient accuracy and the narrow detection range.Multi-mode nano-biological detection technology is an effective way to solve this problem.The reasonable design of multi-mode nano-biological probes,the avoidance of crosstalk between signals and the ensuring the accuracy of detection results arethe keys to achieve efficient multi-mode biological joint inspection.This paper based on the shape codesand the infrared characteristic absorption of the rod-like SiO₂ nanoparticles,combined functional materials such as fluorescent and magnetic materials to construct multi-mode nano-optical probes.The main research contents are as follows:（1）A Pickering emulsion-like system was designed,which used upconversion nanoparticles as the solid surfactants.The upconversion nanoparticles@SiO₂ nanorods with the different aspect ratio were prepared and their growth mechanisms were analyzed.A multi-mode immunoassay strategy based on upconversion nanoparticles@SiO2 nanorods was developed:rapid screening and semi-quantitative detection were achieved under an optical microscope by using its anisotropic shape codes.The infrared fingerprint signal of silica and the upconversion fluorescencewere used to improve the information flux,the sensitivity of the immunoassay and the detection range.The detection limit and the linear range were found out to be 400 fM and 500 fM-500 nM.And the mutual verification between the signals is used to improve the credibility of the test results and avoid the occurrence of false positive results.（2）The Pickering emulsion-like system was modified and the Fe₃O₄ nanoparticles@SiO₂nanorods were synthesized.Multi-mode optical nanoprobes were constructed based on their characteristic infrared absorption and shape codes.The magnetic materials can be rapid enriched under the external magnetic field.This can eliminatethe errors caused by the"coffee ring"phenomenon.The accuracy of assay results can be guaranteed.And diffusion barrier between solid-liquid interfaces and the boundary layereffect in the immunoassay process can be overcame.The sensitivity and speed of the immunoassay can be improved.The detection limit and the linear range were found out to be 920 fM and 1 pM-50 nM.The detection time was shortened from 2 h to 3 min with the aid of a magnetic field.