Citric acid cross-linking of a hydrogel from Aloe vera ( Aloe barbadensis M.) engenders a pH-responsive, superporous, and smart material for drug delivery

• Published in: RSC advances 2024-03, Vol.14 (12), p.8018-8027
• Main Authors: Irfan, Jaffar, Ali, Arshad, Hussain, Muhammad Ajaz, Haseeb, Muhammad Tahir, Naeem-Ul-Hassan, Muhammad, Hussain, Syed Zajif
• Format: Article
• Language: English
• Subjects: Aloe; Chemical synthesis; Chemistry; Citric acid; Colon; Crosslinking; Deionization; Disintegration; Drug delivery systems; Ethanol; Fourier transforms; Hydrogels; In vivo methods and tests; Intestine; Magnetic resonance spectroscopy; NMR; Nuclear magnetic resonance; Retardants; Small intestine; Smart materials; Sustained release; Swelling; Tablets; Thermal analysis
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/d4ra00095a

The current research work is based on the evaluation of a citric acid (CA) cross-linked ( M.) leaf hydrogel (CL-ALH) for pH-dependent and sustained drug release application. The CA was used in different concentrations (1.25, 2.5, 5.0, and 10.0%) to cross-link the ALH using homogenous reaction conditions. The synthesis of CL-ALH was confirmed through Fourier transform and nuclear magnetic resonance spectroscopic studies. The thermal analysis indicated that the ALH and CL-ALH were stable and decomposed in two steps. The scanning electron microscopic images of CL-ALH confirmed its porous nature due to the presence of interconnected channeling. The swelling of CL-ALH was evaluated at pH 1.2, 6.8, and 7.4 as well as in deionized water (DW). High swelling of CL-ALH was observed in DW, and at pH 7.4 and 6.8 whereas, less swelling of CL-ALH was witnessed at pH 1.2. CL-ALH also exhibited swelling/deswelling behavior in DW and ethanol, DW and normal saline, and at pH 7.4 and 1.2. Tablets were prepared from CL-ALH as a release retarding agent demonstrating the sustained release of venlafaxine hydrochloride (VFX) for 8 h. Whereas, VFX was released within 4 h from the ALH-based tablet formulation (un-cross-linked material) indicating the prolonged and sustained release behavior of CL-ALH. The VFX was released from CL-ALH tablets and followed zero-order kinetics. The mechanism followed by VFX release from CL-ALH tablets was non-Fickian diffusion. The fate of the tablet formulation was observed through an X-ray study. The CL-ALH-based tablet safely passed through the stomach of a stray dog without any significant erosion and then disintegrated in the small intestine and colon. These findings confirmed that the CL-ALH is an effective excipient for designing a sustained-release drug delivery system for the small intestine and colon.