Preparation of Biomass-Derived DNA-Chitosan Polyelectrolyte Complex Hydrogels for Economical and Reliable DNA Preservation and Protein Immobilization

DNA-based biomaterials, including polyelectrolyte complex (PEC) hydrogels composed of DNA and other molecules, have received considerable attention due to their programmability and good biocompatibility. However, the cost for DNA synthesis is fairly high, especially for applications where a large quantity of DNA is needed. Construction of biomaterials using biomass-derived DNA is a feasible strategy to address this challenge. In this work, we fabricated and characterized PEC hydrogels with or without covalent cross-linking using biomass-derived DNA and chitosan (CS). Characterization results revealed detailed microstructures and mechanical properties of these two hydrogels, suggesting their potential application in DNA preservation and protein immobilization. We next developed a versatile DNA preservation strategy combining DNA-CS PEC hydrogel-based DNA encapsulation and chitosanase-mediated DNA release, which successfully maintained the integrity and functionality of various types of DNA, i.e., double-stranded DNA (dsDNA), single-stranded DNA (ssDNA), plasmid DNA, and genomic DNA, during the treatment of DNase I and hydrogen peroxide (H2O2). Remarkably, this method also demonstrated good efficiency in protecting DNA containing a broadly used unnatural base pair, dNaM-dTPT3, against the attack of silver ion. Additionally, we developed a convenient and reliable strategy for protein immobilization with the covalently cross-linked PEC hydrogel. This strategy demonstrated good performance in the reusability of the immobilized enzyme, evidenced by 56.4% product yield of the initial cycle of usage achieved by the immobilized horseradish peroxidase (HRP) in the tenth cycle of usage. This work not only broadens the application scope of biomass-derived polymers, but also provides feasible strategies for the sustainable and cost-effective preservation and immobilization of biological macromolecules.