(510g) In-Vivo Fluorescent Nanosensor Implants Based on Hydrogel-Encapsulation: Minimization of Inflammation and the Foreign-Body Response

Nanosensors are promising new tools for various in vivo applications such as sensing, delivery, and imaging. However, a wide range of tissue responses have been reported depending on cell type and various nanocomponent properties. The tissue response is critical in determining the health of the organism and the functional lifetime of the material. While nanomaterial properties can contribute largely to the tissue response, it may be possible to circumvent adverse reactions by formulation of the encapsulation vehicle. In this study, five formulations of poly(ethylene glycol) diacrylate (PEG-DA) hydrogel-encapsulated fluorescent nanosensors were implanted into mice, and inflammatory responses were tracked in order to determine the favorable design rules for hydrogel encapsulation. Five different immunocompromised mice lines were utilized for a comparison across different inflammatory cell populations and responses. Degradation products of the gels were also characterized. Finally, the importance of the tissue response in determining functional lifetime was demonstrated by measuring the time-dependent deactivation following implantation.