Chitosan with defined intrinsic viscosity enables physicochemical entrapment of microplastics under <i>in vitro</i> gastric conditions

H-NMR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) demonstrate that this transition arises from the polymer architecture rather than the surface charge, enabling multipoint interactions and topological confinement within a continuous polymer network. These findings establish intrinsic viscosity as a key design parameter for polymer-based interception of MPs at the biointerface. While the biological fate of the resulting aggregates requires further investigation, this study provides a physicochemical framework for understanding and engineering polymer-MP interactions under gastric conditions. These findings suggest a new material-based approach for reducing the bioavailability of MPs by dietary intervention.