Conventional hydrogels are often fabricated by crosslinking linear polymers or polymerizing monomers and crosslinkers together <i>in situ</i>. More recent work has investigated the formation of hydrogels from nano/microgel building blocks. The properties of such hydrogels are influenced by both the size of and crosslink density within (intra-) the building blocks as well as the degree and type of crosslinks between (inter-) those building blocks, providing multiple levers for controlling hydrogel properties. In this work, amorphous starch nanoparticles (SNPs) were used as the building blocks for creating nanogel network hydrogels. SNPs are extremely small relative to other nanogel building blocks (20-50 nm), are highly cytocompatible and enzymatically degradable, and are produced inexpensively at commercial scales. To form networks, SNPs were methacrylated with varying amounts of methacrylic anhydride (DS 0.05-0.25) and subsequently photopolymerized either to themselves (10-35 wt% precursor solutions) or with methacrylated soluble starch (SS) as a crosslinking agent. SNP-based hydrogels demonstrate significantly reduced protein adsorption relative to soluble starch gels, critical in terms of suppressing foreign body responses to biomaterial surfaces.<br/><br/>Small angle neutron scattering was used to investigate the kinetics (using time-stamped data) and final structure of network formation using the very small angle neutron scattering (vSANS) instrument at NIST (Gaithersburg, MD). Prior to the SANS study, we had hypothesized SNP-only hydrogels would result in higher deformation of the native SNPs during crosslinking relative to soluble starch crosslinked gels and that increasing the degree of methacrylation would minimize SNP perturbations upon crosslinking. Network formation was tracked using the in-line high power fiber optic UV accessory (365 nm). Preliminary data shows that scanning a wide q range (0.015 nm-1&lt;q&lt;5 nm-1) was sufficient for observing gelation kinetics, shown in the attached figure.

Investigating the kinetics and structure of network formation in UV-photopolymerizable starch nanogel network hydrogels using very small angle neutron scattering (vSANS)

2019 Fall National Meeting

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