pH-responsive gelatin polymer-coated silica-based mesoporous composites for the sustained-release of indomethacin

Abstract

This paper prepared drug-loaded mesoporous silica composites with a pH-responsive type. These composites were prepared by using three-dimensional caged silica (SBA-16) as the carrier, 3-aminopropyl trimethoxysilane (APTMS) as the silane coupling agent, and indomethacin (IMC) as the loaded drug, respectively. The drug-loaded precursor NH₂-SBA-16@IMC was prepared by solution diffusion adsorption. Finally, the pH-responsive drug-loaded composites NH₂-SBA-16@IMC@GA were synthesized by wrapping the NH₂-SBA-16@IMC with a condensation polymer of gelatin and glutaraldehyde. The composition and structure of the drug-loaded composites were characterized by FT-IR, XRD, TG, SEM, TEM, and N₂ adsorption-desorption. The in vitro simulated release performance of the drug-loaded composites was investigated at 37 °C under three pH conditions. The results show that the NH₂-SBA-16@IMC@GA can be released in response to specific pH environment, which can effectively control the release speed of the indomethacin.

Keywords: Drug carrier; Gelatin coating; In vitro release; Mesoporous; SBA-16; pH-responsive.

Graphical abstract

Scheme 1

Schematic representation of the preparation process of NH₂-SBA-16@IMC@GA drug-loaded composite.

Fig. 1

The FT-IR spectra of IMC, SBA-16, NH₂-SBA-16, SBA-16@IMC, NH₂-SBA-16@IMC, SBA-16@IMC@GA and NH₂-SBA-16@IMC@GA composites.

Fig. 2

The small-angle XRD patterns of IMC, SBA-16, NH₂-SBA-16, SBA-16@IMC, NH₂-SBA-16@IMC, SBA-16@IMC@GA and NH₂-SBA-16@IMC@GA.

Fig. 3

The wide-angle XRD patterns of IMC, SBA-16, NH₂-SBA-16, SBA-16@IMC, NH₂-SBA-16@IMC, SBA-16@IMC@GA, and NH₂-SBA-16@IMC@GA.

Fig. 4

The Nitrogen adsorption–desorption isotherms of IMC, SBA-16, NH₂-SBA-16, SBA-16@IMC, NH₂-SBA-16@IMC, SBA-16@IMC@GA, and NH₂-SBA-16@IMC@GA.

Fig. 5

The Pore size distribution of IMC, SBA-16, NH₂-SBA-16, SBA-16@IMC, NH₂-SBA-16@IMC, SBA-16@IMC@GA, and NH₂-SBA-16@IMC@GA.

Fig. 6

The thermogravimetric curves of IMC, SBA-16, NH₂-SBA-16, SBA-16@IMC, NH₂-SBA-16@IMC, SBA-16@IMC@GA and NH₂-SBA-16@IMC@GA.

Fig. 7

The electron microscope photos of SBA-16 (A and B), NH₂-SBA-16 (C and D), NH₂-SBA-16@IMC (E and F), and NH₂-SBA-16@IMC@GA (G and H).

Fig. 8

Cumulative release of SBA-16@IMC, NH₂-SBA-16@IMC, SBA-16@IMC@GA, and NH₂-SBA-16@IMC@GA at pH = 2.0.

Fig. 9

Cumulative release of SBA-16@IMC, NH₂-SBA-16@IMC, SBA-16@IMC@GA, and NH₂-SBA-16@IMC@GA at pH = 7.4.

Fig. 10

Drug release of NH₂-SBA-16@IMC@GA under different pH conditions.

Scheme 2

Schematic diagram of the pH-responsive slow release of the NH₂-SBA-16@IMC@GA drug-loaded composite.