Nanoparticle Tunneling in Viscoelastic Hydrogels

Biofilms resist antimicrobial treatment due to their dense, viscoelastic extracellular polymeric substance (EPS), which significantly hinders nanoparticle and drug transport. In this study, we present a multiscale modeling framework to investigate nanoparticle motion through viscoelastic hydrogels, with the goal of enhancing antimicrobial delivery. At the macroscale, fluid flow is governed by the Brinkman-Stokes equations, solved in three dimensions using a finite difference method combined with a level-set immersed boundary approach to model nanoparticle-hydrogel interactions. The hydrogel’s resistance varies spatially and is dynamically coupled to the microscale structural deformation. At the microscale, the hydrogel is modeled as a spring-dashpot network representing the EPS matrix. As the nanoparticle advances, the network deforms: bonds stretch and rupture, creating a tunnel-like void in its wake. This persistent channel reduces local resistance and enhances downstream fluid and nanoparticle transport. Simulations quantify the force required for tunnel formation and the resulting drag on the nanoparticle. Results demonstrate that nanoparticle propulsion not only enables hydrogel penetration but also facilitates long-range transport through sustained tunnel creation. This multiscale framework provides a predictive tool for optimizing nanoparticle-based strategies for biofilm disruption and antimicrobial delivery.