Solid-waste-based keratin/chitosan hydrogel for controlling drug release in vitro

Abstract

The significant quantity of keratin-based solid waste presents a substantial challenge in proper disposal and requires effective management to reduce potential environmental risks. A promising strategy involves the conversion of keratin waste into valuable keratin-based hydrogels. However, these hydrogels typically exhibit insufficient mechanical properties. To address this limitation, this study aimed to develop hybrid hydrogels by integrating keratin with chitosan through alkaline freeze–thaw cycles. The resulting hydrogels, with various ratios, were characterized using scanning electron microscopy and Fourier transform infrared spectroscopy. The analysis revealed the hydrogels had a honeycomb-like structure with excellent mechanical attributes. Among the prepared hydrogels, hydrogel C with keratin/chitosan of 3/2 exhibited a compressive stress and strain of 2.15 MPa and 65.1 %, respectively. The drug loading capacities and controlled release behaviors of the hydrogels were extensively evaluated. Among the various hydrogels tested, hydrogel C demonstrated the most effective controlled release profiles for Rhodamine B (RB) and bovine serum albumin (BSA) at different pH and temperatures. At pH 7.4, hydrogel C achieved maximum cumulative releases of 81.7 % for RB at 50 °C and 31.2 % for BSA at 27 °C. The attainment of equilibrium release occurred after approximately 8 h for RB and 44 h for BSA at 37 °C. In addition, hydrogel C demonstrated exceptional loading properties and controlled release capabilities for cisplatin (CDDP, an anti-cancer drug) without inducing cytotoxic effects on normal and cancer cells. However, CDDP-loaded hydrogel C consistently exhibited cytotoxicity against cancer cells in vitro. These findings collectively underscore the promising potential of keratin/chitosan hybrid hydrogels as drug carriers.