| The thesis consists of five chapters and is listed as follow:Chapter 1:Recent advances in synthesis and biological applications of functionalized quantum dots (QDs) are reviewed, and glucose-sensor based on QDs very recently is included. A mini review of the progresses in the analytical application of resonance light scattering (RLS) is addressed, with special focus on the recent development of QDs as biochemical probes.As an important complementary method of fluorescence sensing, room temperature phosphorimetry (RTP) gives much more advantages, e.g. large Stokes shift, good selectivity, and especially longer and easily measurable triplet lifetimes. In this part, a brief overview of phosphorescent sensors is presented, with specific focus on the merits and application of phosphorescent metalloporphyrins (Pt- and Pd-porphyrins).Chapter 2:A simple method was developed for the modification and functionalization of CdSe QDs with dextran. Characterisation of dextran modified CdSe QDs indicate that dextran partially replaced the original oleic acid chains on the CdSe QDs surface by donating its non-bonding electron pairs on the oxygen atoms to coordinate with the Cd2+ ion and the hydrophilic hydroxyl groups render QDs watersoluble. The dextran-CdSe QDs maintain the fluorescence and also active in carbonate-protein reactions.Chapter 3:A RLS detection method for saccharides was developed using Dex-CdSe-QDs optical probes. The Dex-CdSe-QDs can be aggregated with concanavalin A (Con A), and the change in RLS intensity is used to monitor the extent of aggregation. The presence of glucose competitively binds with Con A, dissociating the Con A/ Dex-CdSe-QDs complexes, affording the RLS intensity change and hence determining glucose concentrations in the range from a few to about 90 mM. Transmission electron microscopy was used to investigate the competitive interaction between glucose and Dex-CdSe-QDs with Con A. The competitive strategy could also be used to detect similar types of saccharides, and the affinities of various monosaccharides for Con A increased in the order galactose<<glucose< fructose<mannose. The proposed method was successfully applied to determine glucose in the human serum. Furthermore, the results demonstrate that the sensitivity of lectin-dextran-modified-QDs interactions increase with dextran molecular mass, and an optimum dextran molecular mass is 500 kDa.Chapter 4:Using sodium sulfite as an oxygen scavenger, meso-tetra (4-N,N,N-tri-methylanilinium) porphyrin-Pd (Pd-TAPP) emits strong and stable room temperature phosphorescence (RTP) in sodium dodecyl sulfate (SDS) micellar solution. Heavy metal ions, including Fe2+, Co2+, Ni2+ and Cu2+, can efficiently quench the phosphorescence of Pd-TAPP. The Stern-Volmer constants increased in the order Fe2+ <Co2+ <Cu2+ <Ni2+, directly reflecting the relative sensitivity of the method for these ions. The detection limits calculated following the 3σIUPAC criteria are:2.3×10-7 mol/L for Cu2+,3.4x10-7 mol/L for Co2+,1.2×10-7 mol/L for Ni2+ and 2.1×10-6 mol/L for Fe2+. The addition of these ions also resulted in reduction of the lifetime (t) of Pd-TAPP. The linear relationship between the concentration of Fe2+, Co2+, Ni2+ or Cu2+ ions and t0/t indicated the dynamic quenching mechanism.Chapter 5:Summary the thesis and make a perspective. |
