RESUMO
An ordered mesoporous silica ( OMS ) was synthesized through hydrothermal process. The synthesized material was characterized by different techniques such as X-ray diffraction, nitrogen adsorption-desorption and transmission electron microscope. The electrochemical characteristics of the OMS modified carbon paste electrode ( OMS/CPE ) were investigated by using cyclic voltammetry and electrochemical impedance spectroscopy. Compared with bare carbon paste electrode ( CPE ) , the OMS/CPE exhibited a larger electrode surface and a faster electron-transfer rate. Electrochemical behaviors and kinetic properties of L-tryptophan ( L-Trp) at the OMS/CPE in the presence of sodium dodecylsulphate ( SDS) were studied. The results showed that the voltammetric response of L-Trp at OMS/CPE was improved due to the synergistic effect of OMS and SDS. The electrochemical oxidation of L-Trp at OMS/CPE in the presence of SDS was an irreversible process involved two electrons and two protons, and the electrode process was controlled by the adsorption step. Some parameters such as SDS concentration, accumulation time, accumulation potential and pH were optimized. Under optimal conditions, the oxidation peak current was linearly proportional to L-Trp concentration in the range of 8. 0×10-8 to 4. 0×10-6 mol/L, with a detection limit of 7. 0×10-8 mol/L (S/N=3 ) . The proposed method was applied for the determination of L-Trp in oral liquid with the recoveries of 99 . 6%-102 . 6%.
RESUMO
OBJECTIVE: To prepare amino-modified ordered mesoporous silica (NH2-OMS) as a drug carrier and test the loading and release properties of poorly water soluble drug carried by it. METHODS: OMS was first prepared using cetyltrimethyl ammonium bromide as the template and then modified by 3-aminopropyl trimethoxy silane to prepare NH2-OMS. N2 adsorption-desorption, X-ray diffraction and thermogravimetric analysis were used to characterize the NH2-OMS. Quercetin was loaded onto NH2-OMS in order to explore the drug loading properties of NH2-OMS. RESULTS: The drug loading and entrapment efficiency of quercetin-NH2-OMS were about 21.0% and 58.2%, respectively, when the concentration of quercetin was 4 mmol·L-1, the reaction time was 24 h and the temperature was set at 50°C. The in vitro release test demonstrated that quercetin-NH2-OMS could form supersaturated solution in simulated intestinal fluid and gastric fluid at concentrations of 13-fold and 27-fold of the thermodynamic solubility of quercetion. CONCLUSION: NH2-OMS, as the carrier for quercetin, can significantly increase its water solubility and release rate in intestinal and gastric fluids.