The Application Of Self-assembled SERS Active Substrate In Detection Of Purine Drugs

Surface-enhanced Raman spectroscopy(SERS) owns most of advantages of Raman spectroscopy. SERS can also provide much structure information of molecule. SERS is a powerful method for trace detection, because it can realize fast and nondestructive detection under mild testing conditions with high sensitivity, good selectivity and perfect resolution. Recently, SERS has been widely applied in many fields. Especially in the aspect of quantitative analysis, SERS shows great potentials. In the paper, SERS was used for detection of purine drugs: 6-thioguanine(6-TG) and 6-mercaptopurine(6-MP) using self-assembled SERS active substrate.The silver nanospheres were prepared via the classic Lee’s method. The prepared silver nanospheres were assembled onto silicon wafer through electrostatic self-assembly for quantitative analysis with good stability and accuracy. Based on Ag NPs@Si substrate, 6-TG was detected by SERS method. The SERS characteristic peak of 6-TG at 1303 cm-1 was selected for quantity analysis. With the 521 cm-1 band of silicon as internal standard, band intensity ratio of 6-TG to silicon, that was I1303/I521, could be used for quantification. The influences of p H value, soaking time and coexisting substances are discussed and optimized in detail. The calibration curve is linear in the concentration range of 0.1-15.0 μmol L-1 and the corresponding correlation coefficient is 0.998. The detection limit is 0.065 μmol L-1(S/N=3). This method was applied for the detection of commercial tablets of 6-TG and results were satisfactory.The silver nanowires were prepared through the improved method of polyol. The prepared silver nanowires were characterized by TEM image, UV-vis spectrum and XRD patterns. The results indicated that the silver nanowires belonged to crystal structure and had a certain length to diameter ratio. The silver nanowires were assembled onto silicon wafer through entropy-driven self-assembly. The 521 cm-1 band of silicon was used as internal standard band. R6 G was used as probe molecule in order to assess SERS performance of the Ag NWs-Si substrate. Based on Ag NPs-Si substrate, 6-MP was detected using surface-enhanced Raman spectroscopy. The linear concentration range of 6-MP is 0.05-3.8 μmol L-1 and the corresponding correlation coefficient is 0.994. The recoveries of 6-MP in two kinds of tablets are between 95.0%and 106.0%and the RSDs are less than 3.68%. The method is credible and satisfactory for detecting 6-MP.