Solid-state encapsulation of Ag and sulfadiazine on zeolite Y carrier

Abstract

by Solid-state Ion Exchange (SSIE) procedure over zeolite Y, followed by deposition of sulfadiazine (SD) by dry mixing was examined for the preparation of topical antibacterial formulations. The ion-exchange and adsorptive properties of the zeolite matrix were utilized for the bactericidal Ag deposition and loading of antibiotic sulfadiazine.Experiments: Assessment of the encapsulation efficiency of both active components loaded by solid and liquid deposition methods was made by X-ray diffraction, TEM, FT-IR spectroscopy and thermogravimetric analysis (TGA). SD release kinetics was also determined.Findings: Sustained delivery of sulfadiazine has been observed from the Ag-modified zeolites compared to the parent HY material. It was found that if SD was loaded in solution, part of the zeolite silver ions was released and interacted with SD, forming AgSD. By solid-state SD deposition, the reaction between the drug and the silver was restricted within the limits of inter-atomic interaction, and total but prolonged drug release occurred.

Solid state NMR characterization of zeolite beta based drug formulations containing Ag and sulfadiazine

“…To give further evidence for the suggested mechanism including the involvement of the silanol groups originating ether from the opening of the SiOHAl bridges or from the framework silanol groups in the vicinity of the framework defect Al sites we measured 1 H spectra of the studied materials. The 1 H spectra of the samples dried overnight at 100 C to remove the strong water signal, demonstrate that the signals within the region of 0-2 ppm The structural transformations in the zeolite materials as a result of Ag + cation loading could be also followed by 29 Si NMR spectroscopy (Fig. 3, le).…”

“…The signal at À110 ppm is characteristic for Si(0Al) species, while the second signal at À103 ppm indicates the presence of Si(1Al) and Si(1OH) species. The single pulse 29 Si spectra reveal that there is a little difference in framework structure and composition as a result of cation exchange or drug loading. This result is not surprising considering the mechanism of cation (drug) induced octahedral to tetrahedral Al transformations as presented in Scheme 1.…”

“…In our previous contribution we have described a new successful and simplied procedure for preparation of dual drug delivery system containing both Ag and sulfadiazine, utilizing zeolite Y as support. 29 The effect of the presence of Ag and the method of the drug introduction on the loading efficiency and the drug release kinetics has been investigated there. Publications in the literature for such a perspective drug delivery system enabling simultaneous controlled release of these two bioactive components are not reported to the best of our knowledge.…”

“…The ve different structural environments of the tetrahedrally coordinated Si atoms, denoted as Si(nAl), where n ¼ 0, 1, 2, 3 and 4, have characteristic chemical shis in the 29 Si NMR spectra, while the relative intensities of the signals for the different Si(nAl) species reect the composition of the zeolite framework. The single pulse 29 Si NMR spectra of the different materials are almost identical (Fig. 3, le) and show two partially overlapping signals.…”

“…This result is not surprising considering the mechanism of cation (drug) induced octahedral to tetrahedral Al transformations as presented in Scheme 1. During this process the silanol groups from the defect sites of the parent zeolite (Si(1OH) species), are transformed into framework Brønsted centers (corresponding to Si(1Al)), which give a signal within the same chemical shi range in the 29 Si spectrum. Thus the loss of signal due to silanol groups is compensated by formation of Brønsted sites by the restoration of the Al in framework positions and the total intensity of the signal at around À103 ppm in the 29 Si spectra resulting from both Si(1OH) and Si(1Al) species is therefore not signicantly affected by the reinsertion of the octahedral Al species into the zeolite framework.…”