Construction Of Plasmonic Nanostructures And Their Applications In Bioanalysis And Nanocatalysis

Local Surface Plasmon Resonance (LSPR) is a unique optical property of coinagemetal nanomaterials. Interactions of light and nanomaterials in nanoscale bring lightabsorption, scattering and even a photothermy effect on metal nanomaterials, whichfacilitate the studies in bioanalytical chemistry field. This unique plasmonic propertyis surprisingly highly sensitive to their size, shape, composition, and charge density aswell as local dielectric environment. In addition to high sensitivity, plasmonicnanostructures provide higher intensity, nonblinking, optical stability and easiness toprepare. In consequence, Au and Ag nanostructures have long been widely utilized fornanoplasmonic chemical and biological sensing, counting, imaging and trackingsystem. By Dark-field microscopy (DFM), single-particle imaging and spectroscopycan be obtained.Firstly, gold nanospheres, gold nanorods, gold nanoprisms, silver nanocubes andgold nanocages were synthesized and characterized.Secondly, we reported a conceptually new nanoplasmonic approach to providehigh-resolution dark-field microscopic (DFM) images of latent fingerprints (LFPs) aswell as the ability to identify cocaine in LFPs with aptamer-bound Au nanoparticles(Au NPs). The level2and level3characteristic details of sebaceous LFPs could beclearly observed. Moreover, by using aptamer-bound Au nanoparticles as imaging andrecognition probes, the cocaine-induced aggregation of Au NPs resulted in a truegreen-to-red color change of the scattered light, providing a quasi-quantative methodto identify cocaine loadings in LFPs.Thirdly, we proposed a nanoplasmonic-antenna mediated indirect strategy formonitoring a catalytic reaction at real time and on single nanoparticle level with darkfield microscopy (DFM), and designed a DNA assembled core-satellites (C/S) Aunanostructure comprising a large Au NP core as a plasmonic antenna and severalsurrounding small Au NPs satellites as heterogeneous catalysts, in which the nanoplasmonic properties and catalytic activities of Au NPs are integrated. Thus, theplasmon band shifts of one single C/S nanostructure throughout the reaction providedan indirect means for monitoring the catalytic reaction. Abundant information of thecatalytic reaction and the catalytic activity of single Au NPs were obtained. This studyexemplifies the power of dark-field microscopy and the concept of plasmonic-antennafor in-depth understanding of different chemical processes in a heterogeneouscatalytic reaction.At last, a summary and prospect was completed. There s plenty of room fornanoplasmonics in the bioanalytical chemistry field.