Preparation of fragrant collagen fibers by cross-linking with β-cyclodextrin and inclusion of l-menthol: characterization, release behavior and reusability evaluation

To solve the poor fragrance retention of collagen-based materials, beta-cyclodextrin derivatives bearing multiple aldehyde groups (MACD) were used to cross-link with collagen fibers (COLF) and subsequently to include l-menthol. The structure and performance of MACD, MACD cross-linked COLF (CD-COLF) and CD-COLF included with l-menthol (MEN/CD-COLF) were characterized by Fourier transform infrared (FTIR), ultraviolet-visible spectroscopy (UV-vis), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results showed that the l-menthol loading content in CD-COLF was 2.05 mg/g, 2.85 times higher than that of the uncross-linked COLF. The stability constant (K-a) of MEN/CD-COLF at 25 degrees C was 364.78 L/mol, Delta H was -19.29 KJ/mol, Delta S was -15.62 J/(mol center dot K), and Delta G was -14.63 KJ/mol, which indicated the inclusion reaction was spontaneous, and the as-formed MEN/CD-COLF was stable. Meanwhile, the MEN/CD-COLF was more difficult to release l-menthol. The release rate was affected by temperature, the release equilibrium was prolonged, and the cumulative release degree was relatively lower. Furthermore, the fragrant collagen fibers were reused by washing with ethanol and dried under vacuum, and the regeneration was repeated 10 times. Therefore, the fragrant collagen fibers with outstanding characteristics could be promising candidates for applying new generation fragrant materials in biomedicine, leather and the textile industry.