Fabrication and characterization of biocompatible pH responsive halloysite nanotubes grafted with sodium alginate for sustained release of phenytoin sodium

Abstract

In this study, a new pH-sensitive nanocomposite based on natural halloysite nanotubes (HNTs) was used as a phenytoin sodium (PhS) carrier. This main objective of this work is to investigate the effect of a polymer coating on the loading and release of PhS. For this purpose, HNTs and sodium alginate (SA) polymer were selected as the encapsulating factors for improving the drug loading and release, and (3-aminopropyl)triethoxysilane (APTES) was selected as a linker for making a chemical bond between the HNTs and SA. Also, the formation of the synthesized drug carrier was proved using various characterization methods including Fourier transform infrared (FT-IR), zeta-potential, energy-dispersive X-ray spectroscopy (EDX), TGA, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The FT-IR results demonstrated the presence of APTES and SA peaks, which supported the modification of the HNTs. The connection of APTES and SA on the external surface of the HNTs was emphasized by the zeta-potential results. Also, EDX was used to describe new elements on the outer surface of the HNTs. TG analysis confirmed the formation of the composite and its thermal stability. Because of the increase in the HNT outer diameter, TEM images showed APTES and SA on the HNTs. In addition, the SEM images displayed the grafting of SA on the external surface of the HNTs due to the nanotube conversion to a rough and indistinguishable form. XRD studies revealed that the HNT crystal structure was unchanged during the synthesis. The profile of drug release and loading was recorded via HPLC. Finally, studying the drug release in the environment of stomach and intestinal simulators demonstrated the effective role of the polymer coating in the controlled release of the drug. Due to the increased encapsulation of the drug in the modified HNTs, and slower and more controlled release, it can be said that the carrier is suitable for the delivery of a phenytoin or similar in the digestive system.