Material properties in unconfined compression of gelatin hydrogel for skin tissue engineering applications

Gelatin (Gel) has been reported as a promising candidate in tissue engineering owing to its easy availability, biocompatibility, and biodegradability. Gel hydrogel is of potential to be cross-linked with different materials to enhance their biocompatibility for cell culture for tissue engineering applications. The mechanical properties of this versatile material, however, have not been thoroughly determined. In this study, the linear elastic (Young's modulus and maximum stress) and non-linear hyperelastic (hyperelastic coefficients) mechanical properties of prepared hydrogels at different contents of Gel (wt%) were measured, and its Young's modulus was compared with that of skin tissue. The prepared cylindrical Gel hydrogels were subjected to a series of unconfined compression tests. The hyperelastic strain energy density function was calibrated using the compressive experimental data. The potential ability of the Yeoh hyperelastic constitutive equation, which has been proposed as the best material model to represent the non-linear behavior of hydrogels, was verified using finite element (FE) simu-lations. The results revealed that the Young's modulus and maximum stress of hydrogels are increased by the addition of Gel. The highest Young's modulus (81 kPa) and maximum stress (24 kPa) were observed for hydrogels with 15 wt% Gel. Results also showed that the hydrogels with a relatively lower content (<7.5 wt%) of Gel have suitable Young's modulus compared with those with a higher content (>7.5 wt%) for skin tissue engineering. The Yeoh material model was closely fitted with the experimental data and could be used in further biomechanical simulations of the hydrogels. The experimental results were also compared well with those