Flexible and Robust Piezoelectric Chitosan Films with Enhanced Bioactivity.

Chitosan (CHT) is a known piezoelectric biomacromolecule; however, its usage is limited due to rapid degradation in an aqueous system. Herein, we prepared CHT film via a solvent casting method and cross-linked in an alkaline solution. Sodium hydroxide facilitated deprotonation, leading to increased intramolecular hydrogen bonding and mechanical properties. The CHT film remained intact for 30 days in aqueous environments. A systematic study revealed a gradual increase in the output voltage from 0.9 to 1.8 V under external force (1-16 N). In addition, the CHT film showed remarkable antibacterial and anti-inflammatory activities under ultrasound stimulation and inhibition of inflammatory cytokines. The CHT films also displayed enhanced cellular proliferation and ∼5-fold faster migration of NIH3T3 cells under US stimulation. Overall, this work presents a robust, biocompatible, and wearable CHT device that can transform biomechanical energy into electrical pulses for the modulation of cell fate processes and other bioactivities.