Synthesis And Characterization Of Biocompatible Core-shell Nanoparticle-Based Surface-enhanced Raman Tags For Bioanalytical Applications

Bioanalysis on nanometer scale has been a topic of significant interest in the developments of current biological and chemical research. Recently, the integration of nanotechnology with biology and analytical chemistry has broad implications in a variety of areas including nano-biosensor and nano-biochips. This dissertation describes the research on biocompatible core-shell nanoparticle-based surface-enhanced Raman scattering (SERS) tags including the novel synthesis methods and their applications in immunoassays and DNA detection. The details are summarized as follows:1. The synthesis of core-shell nanoparticle-based SERS tagsTwo novel synthesis methods have been developed in the preparation of core-shell nanoparticle-based SERS tags including Au@SiO₂ and Ag@SiO₂ based SERS tags. To enrich the kinds of the nanoparticle-based SERS tags and reduce the reaction time during the synthesis of the core-shell nanoparticle-based SERS tags have been the goal in designing these two novel synthesis methods. In the previous literature, it was necessary to pretreat the metal nanoparticles with siliane agent with the group of amino or mercapto to make their surface vitrophilic.(1) In chapter 2, we employed improved synthesis method without the need of coupling agent to prepare Au@SiO₂ nanoparticle-based SERS tags. This synthesis method obviates the competition between the coupling agents and the Raman reporters. Thus, common dyes such as crystal violet and rhodamine 6G can be successfully encapsulated in the Au@SiO₂ core-shell nanoparticle-based SERS tags which efficiently enriched the kinds of SERS tags. Compared to the previous methods reported in literature, the whole synthesis procedure was greatly simplified and the reaction time was significantly reduced. Furthermore, Our experiments have demonstrated the hypothesis that the glass encapsulation chemistry is based on the reaction between silanol groups hydrolyzed by TEOS and citrate anion groups adsorbed onto the gold nanoparticles leading to the formation of a silica layer through further reaction with silanol groups of other hydrolyzed TEOS.(2) In chapter 3, we synthesized Ag@SiO₂ core-shell nanoparticle-based SERS labels using reverse micelle technique or microemulsion being used as a nanoreactor. Using the proposed approach, different processes including the preparation of silver...