Development and characterization of cellulose-based hydrogel patches as a topical delivery system from agricultural waste, infused with aloe vera and colloidal oatmeal from avena sativa.

Abstract

Despite 20% of the world population being afflicted with allergic skin diseases such as urticaria and eczema, oral antihistamines are still most commonly prescribed despite their drawbacks; (e.g., first-generation agents, are blood-brain barrier-crossing while causing drowsiness). Long-term use could result in gastrointestinal disturbances and interactions. Topical drug delivery allows localized application of active ingredients at the site of the irritation, limiting systemic absorption. In this study, biodegradable cellulose-based hydrogel patches incorporated with Aloe vera and colloidal oatmeal extracts were prepared from maize cob as a source of sustainable cellulose. Cellulose was prepared by alkaline treatment and bleaching whilst Aloe vera and oatmeal extracts were prepared by aqueous and hydro-alcoholic extraction, respectively. The patches prepared were skin compatible with pH values ranging between 4.87 and 5.21, high swelling ratios (91.2–141.5%), low moisture contents (9.26–10.90%) and excellent flexibility (214-312 folds). FTIR spectra showed successful crosslinking of cellulose by citric acid, with effective incorporation of the active principles into the hydrogel network. The progressive increase in intensity of the C=O ester band at 1726 cm-1, from F1 to F3, and the presence of a characteristic phenolic C-O stretching band at 1028 cm-1 confirmed the interaction between the components of the patches. The release of phenolics and flavonoids from the extracts into the formulation, was confirmed by UV-visible spectroscopy. The optimum patch (F2, composed of 3% cellulose and 7.5% citric acid) was identified with better physicochemical properties. This study revealed that agricultural waste in low-resource countries like Zimbabwe can be utilized effectively to form sustainable biodegradable hydrogel patches loaded with natural bio-actives for topical application on the skin.