Toward Bioactive Hydrogels: A Tunable Approach via Nucleic Acid-Collagen Complexation

Abstract

Purpose Nucleic acid-collagen complexes (NACCs) are unique biomaterials formed by binding short, monodisperse single-stranded DNA (ssDNA) with type I collagen. These complexes spontaneously generate microfibers and nanoparticles of varying sizes, offering a versatile platform with potential applications in tissue engineering and regenerative medicine. However, the detailed mechanisms behind the nucleic acid-driven assembly of collagen fibers still need to be established. We aim to understand the relationship between microscopic structure and bulk material properties and demonstrate that NACCs can be engineered as mechanically tunable systems. Methods We present a study to test NACCs with varying molar ratios of collagen to random ssDNA oligonucleotides. Our methods encompass the assessment of molecular interactions through infrared spectroscopy and the characterization of gelation and rheological behavior. We also include phase contrast, confocal reflectance, and transmission electron microscopy to provide complementary information on the 3D structural organization of the hydrogels. Results We report that adding DNA oligonucleotides within collagen robustly reinforces and rearranges the hydrogel network and accelerates gelation by triggering rapid fiber formation and spontaneous self-assembly. The elasticity of NACC hydrogels can be tailored according to the collagen-to-DNA molar ratio, ssDNA length, and collagen species. Conclusion Our findings hold significant implications for the design of mechanically tunable DNA-based hydrogel systems. The ability to manipulate hydrogel stiffness by tailoring DNA content and collagen concentration offers new avenues for fine tuning material properties, enhancing the versatility of bioactive hydrogels in diverse biomedical applications. Lay Summary This work is an example of forming fibers and gels with tunable elasticity that stems from the complexation of short-length nucleic acids (on the order of size of aptamers) and collagen, which can be potentially extended to a variety of functionalized hydrogel designs and tailored biomedical applications. Incorporating DNA induces mechanical changes in NACCs. Graphical Abstract

Exploring the Fibrous Nature of Single-Stranded DNA–Collagen Complexes: Nanostructural Observations and Physicochemical Insights

“…NACCs rapidly form a three-dimensional network of fibrils (<1 μm) and larger fiber bundles (>10 μm), mimicking ECM architecture. Acting as a “molecular glue,” ssDNA spontaneously induces the microstructural rearrangement of collagen, forming hierarchical, interwoven fibers within seconds . NACCs are wholly native materials, potentially an ideal candidate to recapitulate a wide variety of ECM signals to cells.…”

“…Acting as a "molecular glue," ssDNA spontaneously induces the microstructural rearrangement of collagen, forming hierarchical, interwoven fibers within seconds. 10 NACCs are wholly native materials, potentially an ideal candidate to recapitulate a wide variety of ECM signals to cells.…”