Ultrasound-responsive piezoelectric thermosensitive PNIPAM/STO hydrogel for minimally invasive antibacterial therapy of neurogenic bladder

Abstract Neurogenic bladder secondary to spinal cord injury remains a significant clinical challenge, with current therapies limited by systemic side effects, invasiveness, or short-lived efficacy of single ultrasound intervention. This study developed a composite thermosensitive hydrogel, using poly(N-isopropylacrylamide as the matrix and strontium titanate piezoelectric nanoparticles as the functional component. At room temperature, the hydrogel exists as a flowable sol for minimally invasive bladder perfusion via catheter, at physiological temperature 37 °C, it rapidly forms a gel to adhere tightly to the bladder mucosa, avoiding flushing by urine. Triggered by low-frequency ultrasound, strontium titanate nanoparticles exhibit a piezoelectric effect inducing charge separation, which catalyzes reactive oxygen species generation to exert antibacterial effects. Cytocompatibility tests via CCK-8 showed high viability of cells, exceeding 90%. Antibacterial experiments demonstrated over 80% antibacterial rate against Escherichia coli and effective inhibition of biofilm formation. This ultrasound-responsive piezoelectric thermosensitive hydrogel provides a promising minimally invasive strategy for addressing neurogenic bladder-related issues.