Multifunctional DNA-Collagen Biomaterials: Developmental Advances and Biomedical Applications

Abstract

The complexation of nucleic acids and collagen forms a platform biomaterial greater than the sum of its parts. This union of biomacromolecules merges the extracellular matrix functionality of collagen with the designable bioactivity of nucleic acids, enabling advances in regenerative medicine, tissue engineering, gene delivery, and targeted therapy. This review traces the historical foundations and critical applications of DNA-collagen complexes and highlights their capabilities, demonstrating them as biocompatible, bioactive, and tunable platform materials. These complexes form structures across length scales, including nanoparticles, microfibers, and hydrogels, a process controlled by the relative amount of each component and the type of nucleic acid and collagen. The broad distribution of different types of collagen within the body contributes to the extensive biological relevance of DNA-collagen complexes. Functional nucleic acids can form these complexes, such as siRNA, antisense oligonucleotides, DNA origami nanostructures, and, in particular, single-stranded DNA aptamers, often distinguished by their rapid self-assembly at room temperature and formation without external stimuli and modifications. The simple and seamless integration of nucleic acids within collagenous matrices enhances biomimicry and targeted bioactivity, and provides stability against enzymatic degradation, positioning DNA-collagen complexes as an advanced biomaterial system for many applications including angiogenesis, bone tissue regeneration, wound healing, and more.

Keywords: DNA aptamers; DNA nanotechnology; bioactive hydrogel; collagen; nucleic acid-collagen complexes.

Figure 1

Timeline illustrating milestones and advancements of DNA-collagen complexes. The groundwork was laid in the 1970s with the discovery of DNA-collagen complexes, which were initially observed binding to glomerular basement membranes and collagen-rich structures. This histology image from a few years later shows immunoglobulin deposits in high-collagen regions of a mouse kidney (Reproduced with permission from ref(35). Copyright 1992, Elsevier.) In the 1990s, exploration focused on the dynamics of in vitro fibril formation, and DNA was found to influence the compactness and order of collagen fibril assembly. This early transmission electron microscopy image from 1997 shows DNA-collagen type I fibrils with distinct cross-banding patterns and increased fibril size (Reproduced with permission from ref(49). Copyright 1997, Elsevier.) In 1999, the advantage of gene delivery via a DNA-collagen scaffold was initially demonstrated in the “Minipellet” model as an implant. The macroscopic appearance of the formulation is shown (Reproduced with permission from ref(131). Copyright 2003, Elsevier.) In the 2000s, theoretical models for the molecular interaction between DNA and collagen were suggested, paving the way for in-depth investigations of assembly dynamics. From 2008, a proposed molecular model of the complex is shown (Reproduced with permission from ref(54). Copyright 2008, American Chemical Society.) 2019 marked a paradigm shift with the introduction of "nucleic acid collagen complexes", termed NACCs, focusing on short, single-stranded DNA interactions with collagen. Notably, the integration of aptamers within collagenous matrices emerged as a critical strategy to induce bioactive responses (Reproduced with permission from ref(56). Copyright 2019, American Chemical Society.)

Figure 2

Schematic representation of the hierarchical structure of collagen and its interaction with nucleic acids, such as DNA. Collagen molecules, organized into fibrils and fibers, maintain their characteristic triple-helical structure and D-band periodicities (67 nm) upon the interaction with DNA, which occurs at the extrafibrillar space.

Figure 3

DNA-collagen complexes are a versatile, multipurpose platform biomaterial. These complexes can form nanoparticles, microfibers, hydrogels, aerogels, and sponges, and interact with inorganic phases (e.g., calcium phosphates) and ions.

Figure 4

(A) An intact retina from a nontreated control (left). A retina 40 days after implantation of a collagen matrix containing a plasmid encoding GFP (middle). A retina 40 days after implantation of a gene-containing collagen matrix containing a combination of plasmids encoding FGF-2 (right). (Reproduced with permission from ref(134). Copyright 2001, Elsevier.) (B) Saline-formulated DNA cannot be retained in wounds, which get filled with clotted blood (top), compared to DNA delivered and retained in complex with collagen-gelatin admixtures (bottom). (Reproduced with permission from ref(137). Copyright 2002, Elsevier.) (C) A hydrogel prepared by vortexing DNA encoding fibroblast growth factor (FGF-4) and gelatin. Naked DNA showed minimal localized expression (top), compared with the spatially expanded expression in the DNA-gelatin hydrogel (bottom). (Reproduced with permission from ref(139). Copyright 2003, Elsevier.)

Figure 5

(A) TEM images of NIH3T3 fibroblasts alone (left) and fibroblasts treated with DNA nanotubes (right). Arrows show the formation of autophagosome-like structures. (Reproduced with permission from ref(163). Copyright 2023, Elsevier.) (B) Phase contrast images of aptamer-functionalized NACC fibers providing biophysical cues to human umbilical vein endothelial cells. Over time, cells remodel NACC fibers (orange arrow) and form cellular bridges (blue arrow). (Reproduced with permission from ref(57). Copyright 2021, Elsevier.) (C) Effects of an atelocollagen formulation on the formation of microtubule networks in endothelial cells. Images of α-tubulin (left panels) and α-tubulin (green) with actin (red) (right panels). In the blank control (top), the microtubule network comprised extended fine microtubule structures. After treatment with atelocollagen complexes with oligodeoxynucleotides, the fine microtubules disassemble, and the network disintegrates (lower). (Reproduced with permission from ref(168). Copyright 2012, Wiley.)