Modeling the urea-actuated osmotic pressure response of urease-loaded hydrogel for osmotic urea biosensor

This paper describes the urea-actuated osmotic pressure response of urease-loaded hydrogel in salt solution, possibly initiating the development of osmotic urea sensor. Herein, a multiphysics model is formulated to elucidate effects of urea concentration on the osmotic pressure of urease-loaded hydrogel by incorporating bio-electrochemical interactions between environmental urea-rich salt solution and functional groups within the hydrogel. The model is directly validated by comparison with published experimental data, where it can capture well the pH- and temperature-induced responsive behaviors of urease-loaded hydrogel. The result shows that the osmotic pressure response of urease-loaded hydrogel enlarges linearly by increasing physiological urea concentration, making it biocompatible for healthcare diagnostic applications. Therefore, the urease-loaded hydrogel is capable of converting bio-electrochemical energy into mechanical one in response to urea-rich biological fluid, demonstrating its potential as a material platform to develop-for the first time-an osmotic urea biosensor.