Net Signal Spectral Analysis Of Multi-component Drugs And Polyelectrolyte Protection Of Quantum Dots And Its Application In Nucleic Acid Detection

In the first part, this paper has studied the determinations of the two effective components contained in compound sulfamethoxazole tablet by using net analyte signal of ultraviolet spectrum.Since the spectral net signal of the analyzed component was orthogonal to the spectral subspace spanned by the other drug spectra and the assistant ones, the spectral disturbance of the analyzed component should be eliminated, and then its spectral net signal should be directly proportional to its concentration. Based on the basic idea, the analyzed component of the drug was determined. This paper has studied the determinations of the two effective components sulfamethoxazole (SMZ) and trimethoprim (TMP) contained in compound sulfamethoxazole tablet by using ultraviolet spectroscopy. The linear ranges of SMZ and TMP were 0.48-7.84μg/ml(r = 0.9981) and 0.12-1.5μg/ml (r = 0.9986), the corresponding average recoveries were 99.5% and 101.0%, and the relative standard deviations were 1.87% and 3.60%, respectively. The method was simple, fast and accurate. It could be used in acid condition to simultaneously determine SMZ and TMP in the compound sulfamethoxazole tablet.In the second part, this paper have studied the synthesis of water-soluble quantum dots (QDs), the polyelectrolyte-protected CdTe quantum dots and its application in nucleic acids detection.CdTe QDs of different colors with the ligand thioglycolic acid have been synthesized in water by using the materials CdCl₂, Te, NaBH₄ and thioglycolic acid in the conditions of heating and refluxing. The high quality CdTe QDs with green, yellow and orange fluorescence have been obtained by condition optimization. The green CdTe QDs had the highest fluorescence quantum yields (about 45%). By using the synthesed CdTe QDs and the sulfur source thioacetamide, we have synthesed the core-shell CdTe/CdS QDs (612nm) of red color. Their fluorescence quantum yields were further improved and the synthesis time of red-color QDs were shortened greatly.Two kinds of polyelectrolyte-protected QD nanocomposites (QD-PDADMAC and QD-DADMAC-PAA) have been synthesized by electrostatic adsorption. Such nanocomposites showed curly-shaped band-like morphology with unequal length. The width of the band was 3-5nm. The band-like nanocomposites can effectively prevent thiol ligands dropping out from the surface of QD, so it had higher fluorescence stability than one without polyelectrolyte protection, besides, it also had higher fluorescence stability against quench caused by moderate of acid, alkali, oxidation than naked QD without polyelectrolyte protection. At the same time, the fluorescence quantum yields of the obtained QD-Polyelectrolyte nanocomposites did not reduced compared with QD and the biological compatibility were also remained. So this band-like nanocomposites improved the fluorescence stability of QD in applications.QD-PDADMAC-P nano fluorescence probes have been obtained by electrostatic adsorption and then nucleic acid probe P haved been fixed on the surface of QD-PDADMAC nano-band. This method was more simple and fast than traditional one, which the probe P were fixed on the surface of nanoparticle by chemical reaction. Morever, we applied this kind of probe to the quantitative detection of nucleic acid. Based on the probe QD-PDADMAC-P, we established the fluorescent resonance energy transfer system between the QD-PDADMAC with the emission wavelength 545nm and ethidium bromide for the quantitative determination of nucleic acid. For this method, the liner range was 154-770nM, the relation coefficient 0.998, and the limit of quantification 154 nM.