دانلود رایگان مقاله ژل پکتین - سیلیکا به عنوان دی ماتریکس برای آزادسازی دارو در دستگاه گوارش

ABSTRACT

The synthesis of pectin-silica gels for controlled drug release in gastrointestinal tract (GIT) using low methoxyl (LM) and high methoxy (HM) pectins and tetraethoxysilane (TEOS) as precursor is described. The FTIR spectra of the pectin-silica gels show intense absorption bands at 1246 cm−1 and 802 cm−1 corresponding to the vibrations C O Si bonds, which absent in the FTIR spectra of the native pectins that indicate the formation covalent bond between silica and pectin macromolecules in the pectin-silica gels. Pectin-TEOS, pectin-Ca-TEOS and pectin-TEOS-Ca beads with mesalazine are synthesized by different combinations of sol-gel method using TEOS and ionotropic gelation method using calcium chloride. The best resistant of pectin-TEOS and pectin-Ca-TEOS beads during incubation in simulated gastric fluid for 2 h and subsequently in simulated intestinal fluids for 18 h is indicated. Pectin-TEOS beads are characterized by higher encapsulation efficiency (to 28%) than pectin-Ca-TEOS beads (to 16%). The drug release of pectinsilica beads in simulated GIT occurs gradually up to 80% and is directly dependent on the hardness of the beads. The surface morphology of beads is shown. The use of pectin-silica beads is promising with regard to the development of controlled release of drug formulations.

4. Conclusions

A new method for producing pectin-silica gels has been developed. The comparative synthesis of pectin-silica gels by sol-gel gelation of LM and HM pectins with precursor TEOS was obtained. It was shown that synthesis pectin-silica gels can occur in an acidic environment without the use of ethanol. The experiment revealed that the gelation depend on degree of methylation of pectin and TEOS concentration. In the case of LM pectin, monolithic hydrogels were generated through the 24 h starting from minimum concentration of TEOS (0.25 M). Whereas in the case of HM pectin, monolithic hydrogels were produced only at high TEOS concentration (0.75 M). The FTIR spectra of synthesized pectin-silica gels in presence of ethanol and without it are similar and indicate the formation of hydrogen and covalent bonds between the silica and pectin. The FTIR spectra show intense absorption bands at 1246 cm−1, 1132 cm−1, 802 cm−1, 492 cm−1 and 964 cm−1 corresponding to the vibrations C O Si , Si O Si bonds and Si OH groups accordingly, which are not observed in the FTIR spectra ofthe native pectins.