Chitin-Core Chitosan-Sheath Nanowhiskers as a Multifunctional Bionanofiber Modality for Hydrogel Microspheres in a Micromolding-Based Fabrication-Conjugation Approach

Simple and tunable production of macroporous hydrogel microparticles for rapid protein quantification in a suspension array format remains a major challenge. We exploit biologically derived rigid nanofibers as a multifunctional modality in a robust micromolding method using a postfabrication bioconjugation approach to address this challenge. Specifically, chitin-core chitosan-sheath nanowhiskers (CSNW) with a tunable amine titer are prepared under mild deacetylation reaction conditions. Transmission electron microscopy, dynamic light scattering, and dynamic viscosity measurements show rigid bionanofibers with substantially lower viscosity compared to solubilized linear forms of chitosan and other biopolymers, suggesting improved handling and manufacturability. Fluorescent labeling studies on polyacrylamide-based microspheres fabricated via micromolding indicate stable and uniform incorporation of CSNW in hydrogel microspheres and the readily tunable chemical functionality of CSNW. Further, reliable fabrication using acrylate-modified CSNW as the primary cross-linker, along with selective and improved protein conjugation kinetics, attests to the macroporous network of the hydrogel microparticles and illustrates the multifunctionality of CSNW. We thus envision that our approach in harnessing potent bionanofibers and micromolding can be readily extended to produce a wide variety of multifaceted microscale materials with a multitude of desirable features with improved performances for applications such as rapid biosensing and biodiagnostics.