Extraction of Keratin from Waste Hair Samples for Biotechnological Applications

Research on synthetic tissues and tissue engineering platforms has gained significant attention due to the increasing demand for materials with enhanced stability, biocompatibility, low toxicity, and cost-effectiveness. In this context, biomolecule-based polymers have emerged as promising alternatives for biomedical applications. Keratin, a fibrous protein extracted from human hair, represents an abundant and sustainable biomaterial biomaterial source. Its stability is primarily attributed to its high cysteine content enabling disulfide bond formation along with contributions from other amino acids such as proline. In this study, keratin was isolated from waste human hair using urea-based and sodium sulfide-based extraction methods, and their efficiencies were comparatively evaluated. Using 1.0 g hair samples, the urea-based method yielded 11.8±0.7%, while the sodium sulfide method yielded 13.2±1.0%, with batch-to-batch variation below 8%, indicating good reproducibility. The soluble protein concentrations of purified keratin solutions after dialysis were determined as 189.3±12.0 mg/L for the urea method and 256.5±18.0 mg/L for the sodium sulfide method. Structural and morphological analyses confirmed the proteinaceous nature of keratin. The results indicate that the urea-based method in extraction preserves more native-like and amorphous characteristics, whereas the sodium sulfide method induces stronger sulfur-related modifications and partial structural rearrangement.