Ear defects present at birth or acquired through trauma can lead to external defects or hearing loss, necessitating ear reconstruction. Per WHO statistics, hearing and cosmetic ear diseases affect 6.5% of the world's population. Advances in scaffold fabrication have enabled engineering of human sensory organs like the nose and ear in vitro with adequate functional performance. Such progress allows simultaneously targeting two challenges in engineered sensory organs, especially the ear. First, precise reconstruction of the auricular cartilage, and second, providing a triboelectric-based device to rebuild the hearing function of the inner ear. In the first part, after silk nanofibril extraction, an alginate-silk nanofibril nanocomposite hydrogel was 3D printed into an auricular shape. Characterizations showed shear thinning behavior required for extrusion-based 3D printing was improved. The viscosity of 2 wt% nanofibril-laden alginate increased from 102×8.2 to 103×2.8 Pa.s at a similar shear rate range of 0.1-100 s-1. In contrast, neat alginate viscosity only increased from 104×3.1 to 105×1.3 Pa.s. Moreover, the interaction between silk nanofibrils and the alginate matrix significantly enhanced the mechanical, biological, and structural stability properties in a simulated body environment. Adding 2 wt% nanofibrils improved the compressive strength (~2.5 times), tensile strength (~5 times), and elastic modulus (~3 times) of alginate. The highest cell viability percentage (136±3% of control) was observed in scaffolds with 2 wt% nanofibrils based on cytotoxicity assays. In the next section, fibrous membranes with different polyvinylidene fluoride/polycaprolactone ratios were electrospun, and after structural optimization, the triboelectric output power of the nanogenerator with varying percentages was measured. Results showed combining polyvinylidene fluoride and polycaprolactone (PCL:PVDF) at ratios of 2:1 and 1:3 at 15 and 17 wt% improved the peak nanogenerator power output from 227 to 1033 nW. The biomimetic spiral array triboelectric nanogenerator was then characterized, and after optimizing the polymer composition in the triboelectric constructs, the system's competence in yielding open circuit voltage outputs in response to a 0-20 kHz audio file was eva‎luated. The arrays showed sensitivity in the 180- 650 Hz range with increasing length from 12-19 mm. Fourier transform infrared spectroscopy and differential scanning calorimetry confirmed the presence of the beta phase and its effect on the nanogenerator output. In summary, the 2 wt% silk nanofibril-laden alginate hydrogel could be a suitable bioink for external ear reconstruction. The parallel-fibered PCL:PVDF (10:5) fibrous membrane may suit as a layer in the designed triboelectric device to mimic the inner ear's hearing function

مهشيد خرازيهاي اصفهاني

نرگس جوهري , محمد خدائي