2D DNA nanoporous scaffold promotes osteogenic differentiation of pre-osteoblasts

Exploring the diverse biomedical applications of programmable and multifunctional DNA nanomaterials

DNA nanoparticles hold great promise for a range of biological applications, including the development of cutting-edge treatments and diagnostic tests. Their subnanometer-level addressability enables precise, specific modifications with a variety of chemical and biological entities, making them ideal as diagnostic instruments and carriers for targeted delivery. This paper focuses on the potential of DNA nanomaterials, which offer scalability, programmability, and functionality. For example, they can be engineered to provide highly specific biosensing and bioimaging capabilities and show promise as a platform for disease diagnosis and treatment. Successful operation of various biomedical nanomaterials has been demonstrated both in vitro and in vivo. However, there are still significant challenges to overcome, including the need to improve the scalability and reliability of the technology, and to ensure safety in clinical applications. We discuss these challenges and opportunities in detail and highlight the progress and prospects of DNA nanotechnology for biomedical applications.

DNA hydrogels for bone regeneration

DNA-based biomaterials have been proposed for tissue engineering approaches due to their predictable assembly into complex morphologies and ease of functionalization. For bone tissue regeneration, the ability to bind Ca2+ and promote hydroxyapatite (HAP) growth along the DNA backbone combined with their degradation and release of extracellular phosphate, a known promoter of osteogenic differentiation, make DNA-based biomaterials unlike other currently used materials. However, their use as biodegradable scaffolds for bone repair remains scarce. Here, we describe the design and synthesis of DNA hydrogels, gels composed of DNA that swell in water, their interactions in vitro with the osteogenic cell lines MC3T3-E1 and mouse calvarial osteoblast, and their promotion of new bone formation in rat calvarial wounds. We found that DNA hydrogels can be readily synthesized at room temperature, and they promote HAP growth in vitro, as characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. Osteogenic cells remain viable when seeded on DNA hydrogels in vitro, as characterized by fluorescence microscopy. In vivo, DNA hydrogels promote the formation of new bone in rat calvarial critical size defects, as characterized by micro-computed tomography and histology. This study uses DNA hydrogels as a potential therapeutic biomaterial for regenerating lost bone.

Exploring the robustness of DNA nanotubes framework for anticancer theranostics toward the 2D/3D clusters of hypopharyngeal respiratory tumor cells

This study aimed to develop a robust approach for the early diagnosis and treatment of tumors. Short circular DNA nanotechnology synthesized a stiff and compact DNA nanotubes (DNA-NTs) framework. TW-37, a small molecular drug, was loaded into DNA-NTs for BH3-mimetic therapy to elevate the intracellular cytochrome-c levels in 2D/3D hypopharyngeal tumor (FaDu) cell clusters. After anti-EGFR functionalization, the DNA-NTs were tethered with a cytochrome-c binding aptamer, which can be applied to evaluate the elevated intracellular cytochrome-c levels via in situ hybridization (FISH) analysis and fluorescence resonance energy transfer (FRET). The results showed that DNA-NTs were enriched within the tumor cells via anti-EGFR targeting with a pH-responsive controlled release of TW-37. In this way, it initiated the triple inhibition of "BH3, Bcl-2, Bcl-xL, and Mcl-1". The triple inhibition of these proteins caused Bax/Bak oligomerization, leading to the perforation of the mitochondrial membrane. This led to the elevation of intracellular cytochrome-c levels, which reacted with the cytochrome-c binding aptamer to produce FRET signals. In this way, we successfully targeted 2D/3D clusters of FaDu tumor cells and achieved the tumor-specific and pH-triggered release of TW-37, causing tumor cell apoptosis. This pilot study suggests that anti-EGFR functionalized, TW-37 loaded, and cytochrome-c binding aptamer tethered DNA-NTs might be the hallmark for early tumor diagnosis and therapy.

Disrupting biofilm and eradicating bacteria by Ag-Fe3O4@MoS2 MNPs nanocomposite carrying enzyme and antibiotics

In this study, novel multilayered magnetic nanoparticles (ML-MNPs) loaded with DNase and/or vancomycin (Vanc) were fabricated for eliminating multispecies biofilms. Iron-oxide MNPs (IO-core) (500-800 nm) were synthesized via co-precipitation; further, the IO-core was coated with heavy-metal-based layers (Ag and MoS₂ NPs) using solvent evaporation. DNase and Vanc were loaded onto the outermost layer of the ML-MNP formed by nanoporous MoS₂ NPs through physical deposition and adsorption. The biofilms of S. mutans or E. faecalis (or both) were formed in a brain-heart-infusion broth (BHI) for 3 days, followed by treatment with ML-MNPs for 24 h. The results revealed that coatings of Ag (200 nm) and ultrasmall MoS₂ (20 nm) were assembled as outer layers of ML-MNPs successfully, and they formed Ag-Fe₃O₄@MoS₂ MNPs (3-5 μm). The DNase-Vanc-loaded MNPs caused nanochannels digging and resulted in the enhanced penetration of MNPs towards the bottom layers of biofilm, which resulted in a decrease in the thickness of the 72-h biofilm from 48 to 58 μm to 0-4 μm. The sustained release of Vanc caused a synergistic bacterial killing up to 96%-100%. The heavy-metal-based layers of MNPs act as nanozymes to interfere with bacterial metabolism and proliferation, which adversely affects biofilm integrity. Further, loading DNase/Vanc onto the nanoporous-MoS₂-layer of ML-MNPs promoted nanochannel creation through the biofilm. Therefore, DNase-and Vanc-loaded ML-MNPs exhibited potent effects on biofilm disruption and bacterial killing.

Nanoscale packing of DNA tiles into DNA macromolecular lattices

Nanoscale double-crossovers (DX), antiparallel (A), and even half-turns-perimeter (E) DNA tiles (DAE-tiles) with rectangular shapes can be packed into large arrays of micrometer-scale lattices. But the features and mechanical strength of DNA assembly made from differently shaped large-sized DAE DNA tiles and the effects of various geometries on the final DNA assembly are yet to be explored. Herein, we focused on examining DNA lattices synthesized from DX bi-triangular, DNA tiles (T) with concave and convex regions along the perimeter of the tiles. The bi-triangular DNA tiles "T(A) and T(B)" were synthesized by self-assembling the freshly prepared short circular scaffold (S) strands "S(A) and S(B)", each of 106 nucleotides (NT) lengths. The tiles "T(A) and T(B)" were then coupled together to get assembled via sticky ends. It resulted in the polymerization of DNA tiles into large-sized DNA lattices with giant micrometer-scale dimensions to form the "T(A) + T(B)" assembly. These DNA macro-frameworks were visualized "in the air" under atomic force microscopy (AFM) employing tapping mode. We have characterized how curvature in DNA tiles may undergo transitions and transformations to adjust the overall torque, strain, twists, and the topology of the final self-assembly array of DNA tiles. According to our results, our large-span DX tiles assembly "T(A) + T(B)" despite the complicated curvatures and mechanics, was successfully packed into giant DNA lattices of the width of 30-500 nm and lengths of 500 nm to over 10 μm. Conclusively, the micrometer-scale "T(A) + T(B)" framework assembly was rigid, stable, stiff, and exhibited enough tensile strength to form monocrystalline lattices.