| In 1993, Pasteraack et al. proposed resonance light scattering (RLS) technique originally and applied to the characterization of supermolecular assemblies. Then, Huang et al. applied that technique firstly to establish a sensitive and novel assay of nucleic acids in 1996. After that, RLS technique attracted attention due to its simple manipulation, high sensitivity and convenient experimental conditions. In this decade, RLS technique has been extensively and successfully utilized in various fields. Nowadays, RLS technique has become a powerful and routine assay in analytical chemistry.However, with the further development of RLS technique, the limitations of RLS technique are clarified gradually. First, RLS technique suffers from serious inference from its coexisting foreign substances in bulk solution, obstructing the further improvement of selectivity and sensitivity in biomedical analysis. Poor reproducibility, narrow linear range, laborious operation and large sample-consumption, all of those block the further development of RLS technique. Second, the RLS signals are not stable and the reproducibility is poor, as a result unstable reagents cannot be used asprobe in RLS experiments. Third, RLS technique as a routine analytical method is still not applied in on-line detection, actually affecting its promising prospect in applied science.To overcome these drawbacks, we combine RLS technique with total internal reflection at water/oil interface based on the theory that the amphiphilic species will be repelled from both water and oil phases, but could be well adsorbed at the interfacial region. Thus, analyte can interact with specific probe to form amphiphilic species and be absorbed at the liquid/liquid interface as a result the analyte can be separated from coexisting foreign substances effectively. Due to the analytes being separated from the bulk and their enrichment at the interface, the analytes can be detected with high selectivity and sensitivity by TIR-RLS technique. Meanwhile, we also innovatively combine flow rejection analysis (FIA) with RLS technique and successfully develop the FIA-RLS coupled technique. The FIA-RLS coupled technique integrates the characteristics of FIA such as good reproducibility, operating simplicity and high throughput with the RLS features such as simplicity in apparatus and high sensitivity. Those novel RLS techniques would undoubtedly enhance the performance of RLS technique in the aforementioned limitations.In this contribution, three parts are included. The first part deals with the assay of nucleic acids, heparin and berberin which were proposed with good selectivity and sensitivity by TIR-RLS technique at water/oil interface. The second part deals with the FIA-RLS coupled technique. The third part deals with resonance light scattering (RLS) rationmetric method and its application in the investigating the aggregation of cationic porphyrin on heparin.The followings are the main points of the first part:(1) At pH 3.3 and ionic strength 0.003 mol L-1, nucleic acids, including calf thymus DNA(ctDNA), fish sperm DNA(fsDNA), and yeast RNA(yRNA), have been determined with good selectivity and sensitivity at H2O/CCl4 interface by TIR-RLS technique. Under optimal conditions, amphiphilic complexes produced by nucleic acids and cetyltrimethylammonium bromide (CTMAB) are absorbed at the H2O/CCl4interface. All of these induce significantly enhanced TIR-RLS signals with the maximum peak located at 370.0 nm at the interface. It was found that the enhanced TIR-RLS intensity is in good proportion to the concentration of nucleic acids in the range of 0.06-2.5, 0.015-3.5, and 0.046-3.5 fig ml-1 for ctDND, fsDNA, and yRNA, respectively, and their limits of detection (3 a) are 6.0 ng ml-1, 1.5ng ml-1 and 4.6ng ml-1 correspondingly. Artificial samples with complicated and highly interfering backgrounds were analyzed satisfactorily.(2) At pH 7.0 and ionic strength 0.008 mol L-1, ternary amphiphilic species formed by nucleic acids, including ctDNA, fsDNA and yRNA...
|
PDF Full Text Request