(180bc) Fabrication of Chitosan-Poly(ethylene glycol) Hybrid Hydrogel Microparticles Via Replica Molding and Its Application Toward Facile Conjugation of Biological Molecules Using Copper-Free Click Chemistry

Facile conjugation of biological molecules on robust formats is important in many application areas such as biosensing, medical diagnostics, controlled drug delivery, environmental or bioterrorism detection. One example of the existing formats for biomolecular conjugation is nano and microparticles based on the amino polysaccharide chitosan rising from the abundant primary amine groups that offer covalent binding sites. Yet, chitosan’s high viscosity, poor solubility in water and low mechanical strength due to its rigid crystalline structure have limited its utility in biofunctionalized hydrogel fabrication. While the chitosan based particles can be formed with water-in-oil emulsion method, the shape of particle is usually limited to spheres. Replica molding (RM) offers simple, robust, and inexpensive procedure to allow for reliable replication of complex shapes in low micrometer dimensions. Also, the copper catalyzed click chemistry has been considered as a powerful coupling method for the conjugation of biomolecules although severe structural damage to biomolecules caused by the copper ion has been reported.

In this presentation, we demonstrate facile fabrication of chitosan/PEG (polyethylene glycol) hybrid hydrogel microparticles via replica molding along with a simple, mild and efficient conjugation approach for the conjugation of biomolecules onto the particles. Specifically, we utilized chitosan/PEGDA (polyethylene glycol diacrylate) blended prepolymer solution to fabricate hydrogel microparticles with uniform and well-defined dimensions and shapes via RM. The conjugation and distribution of chitosan molecules within the PEG networks as well as the chemical reactivity of chitosan’s amine groups were confirmed via fluorescent labeling. The results show that the chitosan molecules are mostly located near the particle surfaces while particles with high PEG concentration yielded retention of chitosan molecules within the core area, presumably due to small mesh size of the polymeric network. Next, the primary amines in the chitosan/PEG microparticles were exploited for copper-free click chemistry-based conjugation of biological molecules such as DNA. The results show high density and selective conjugation of probe DNAs near the particle surface where mass transfer limitation is minimal. Upon conjugation of probe DNAs with microparticles via copper-free click chemistry, the particles were also examined for application as hybridization assay platforms.

Combined these results demonstrate facile fabrication and biomolecular conjugation of hybrid bio-/synthetic polymer microparticles via replica molding, enabling efficient use of precious biomolecules. We envision that the methodologies presented here may find wide application areas where efficient fabrication and conjugation of precious materials are highly desired. In this presentation, our recent results on facile assembly of supramolecular targets such as viruses will also be highlighted.