Analytical Applications Of Plasmon Resonance Light-scattering And Surface Light-scattering Technique In Biochemical Medicament

Light scattering spectra, a branch of modern spectrum analysis, play an important role in analytical science. After a thorough review about the light scattering technique, especially resonance light scattering (RLS) technique theoretically and practically, the studies are started with the aim of developing several methods for the target detection with simplicity, greater sensitivity and time-saving using gold nanoparticles as plasmon resonance light-scattering (PRLS) probe, and improving the selectivity of RLS technique by measuring surface-enhanced light-scattering (SELS) signals on solid phase. The main content is as follows:(1) Using gold nanoparticles as PRLS probe, we investigate the process of the aggregation of gold nanoparticles occured due to their interaction with Cap, a typical clinic organic drug. In aqueous medium of pH 2.09, there are about 2.2×10³ Cap molecules covalently binding to the surface of a 10-nm diameter gold nanoparticle through the thiol functional group of Cap, and thus forms a core-shell assembly of [(Au)₃₁₀₀₀]@[(Cap)₂₂₀₀], displaying strong enhanced PRLS signals in the plasmon resonance absorption (PRA) region of gold colloid. The PRLS intensities characterized at 553.0 nm were found to be proportional to the concentration of Cap over the range of 0.1-1.7 mg l^-1 with the determination limit (3a) of 32.0μg l^-1. With that, Cap in pharmaceutical preparations could be determined with the recovery of 97.0-104.5% and RSD of less than 2.4%.(2)Based on the fact that the selective adsorption of single strand DNA (ssDNA) on gold nanoparticles can stabilize the gold nanoparticles against aggregation at concentrations of salt but the double strand DNA (dsDNA) can't do, and the Hg²⁺ ion-mediated T-Hg^â…¡-T pair was more stable than the Watson-Crick (WC) A-T pair, we design a simple homogeneous PRLS assay for the detection of Hg²⁺. To begin with, we mix the d(T₆) and the different concentration of Hg²⁺, and then Hg(2+)-mediated T-T base pair (T-Hg^â…¡-T pair) forms. therefore, the extent of the mixtures' stabilizing the gold nanoparticles against aggregation at concentrations of salt is different, and results in different PRLS signals with the variation of concentration of Hg²⁺. Consequently, the PRLS intensities characterized at 556.0nm under optimal experimental conditions were found to be proportional to the concentration of Hg²⁺ over the range of 4.0×10^-8 mol L^-1 - 6.0×10^-7 mol L^-1 with the determination limit (3a) of 1.0×10^-9 mol L^-1.(3) Based on the molecular recognition of human immunoglobulin (IgG) with Protein A (SpA), a cell wall-associated Protein of 5. aureus on the surface of solid phase, we devoloped a light-scattering method with selective identification and detection of pathogenic bacteria, 5. aureus. It was found that the molecular recognition on glass slide sensing area could result in strong SELS signals, and the SELS intensity (â–³I) increases proportionally with the concentration of 5. aureus over the range of 2.5×10⁵～1.0×10⁸ CFU mL^-1, 2.0×10⁵～1.0×10⁸ CFU ml^-1 with right angle light-scattering (RALS) and backward angle light-scattering (BALS) signals detection mode, respectively.