Application Of Surface Plasmon Resonance In Analytical Chemistry, And Study On Functionalized Adsorbent For Separation And Preconcentration Of Trace Elements

Since the first application of the surface plasmon resonance (SPR) phenomenon for sensing almost three decades ago, this method has made great strides both in terms of instrumentation development and applications. SPR sensor technology has been commercialized and SPR biosensors have become a central tool for characterizing and quantifying biomolecular interactions. This paper mainly described the application of SPR on resistance of protein non-specific adsorption and the interaction between bio molecules. Moreover, we studied the relationship of SPR and electrochemistry, and detected the intermediate in the reaction by EC-SPR. At the last chapter, we focused on the preparation of the adsorption material for the pre-concentration and separation of trace components. The more detailed novelty of this work can be categorized as following:1. A study of protein resistance of poly (ethylene glycol) (PEG), HS(CH2)11(OCH2CH2)nOH (n=3,4, and 6), self-assembled mono layers (SAMs) on gold surfaces was presented here. Hydroxyl-terminated PEG-SAMs were chosen to avoid the hydrophobic effect, particularly at high packing densities. The structure of the bare gold and PEG-SAM surfaces were characterized by atomic force microscopy (AFM), Ellipsometry and FT-IR Protein adsorption on these surfaces was investigated by surface plasmon resonance (SPR). Compared with PEG2-and PEG4-SAMs, PEG6-SAMs show great resistance of protein adsorption.2. This chapter describes the immobilization of IgG on mixed self assembled monolayers (SAMs) of alkanethiolates with different ratio on gold generated from HS(CH2)11(OCH2CH2)6OH and the HS(CH2)11(OCH2CH2)6CH2COOH. The immobilization was achieved by a two-step procedure:generation of reactive N-hydroxysuccinimidyl esters from the carboxylic acid groups in the SAM and coupling of these groups with amines on the protein or ligand. Because this method involves a common reactive intermediate that is easily prepared, it provides a convenient method for attaching ligands to SAMs using surface plasmon resonance spectroscopy. These SAMs were highly resistant to nonspecific adsorption of proteins. The pH of the protein buffer solution that influenced the amount of the protein immobilized was investigated. The kinetics of IgG and Anti-IgG binding was calculated and analysed.3. A quantitative formalism of electrochemical Surface Plasmon Resonance (EC-SPR) was developed for studying electrochemical reactions. The EC-SPR signal from the reactions was found to be a convolution function of electrochemical current, and therefore, EC-SPR is a powerful tool that can provide information similar to the conventional current-based electrochemical techniques. As an example, potential-sweep EC-SPR was analyzed in details and found to provide a new way to measure convolution voltammetry without numerical integration. In addition to the benefits provided by the conventional convolution voltammetry, the EC-SPR possesses several unique advantages, including 1) spatial resolution that is particularly attractive for studying heterogeneous reactions,2) optical properties of the reactions species that may assist identification of reaction mechanisms; and 3) high surface sensitivity for studying surface binding of the reaction species. Experiments and numerical simulations were carried out for a model system, hexaammineruthenium (â…¢) chloride. The simultaneously measured electrochemical current and SPR response confirmed the relationship between the two quantities, and the numerical simulations were in excellent agreement with the measurements.4. The electrochemical reaction of Hydroquinone-Benzoquinone (HQ-BQ) system in acetonitrile was studied by a flow-through Electrochemical Surface Plasmon Resonance (EC-SPR) technique. The semiquinone radical anion (BQ*-) was detected as a large negative SPR shift for the first time by the hyphenated technique. The real time SPR signal shows the entire reaction process of the BQ including generation, transformation and disappearance. The lifetime of the BQ in the reaction was extracted by comparing the SPR signals along the flow stream The study demonstrates that the flow-through EC-SPR is a powerful tool for detecting not only surface bindings, but also solution phase chemical reactions. In addition, it is especially suitable for detecting unstable intermediate reaction products, which are difficult to measure using conventional analytical methods.5. A new tris(2-aminoethyl) amine (TREN) functionalized silica gel (SG-TREN) was prepared and investigated for selective solid-phase extraction (SPE) of trace Cr(â…¢), Cd(â…¡) and Pb(â…¡) prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Identification of the surface modification was characterized and performed on the basis of FT-IR The separation/ preconcentration conditions of analytes were investigated, including effects of pH, the shaking time, the sample flow rate and volume, the elution condition and the interfering ions. The application of this modified silica gel to preconcentration trace Cr(â…¢), Cd(â…¡) and Pb(â…¡) of two water samples gave high accurate and precise results.