Many cancers show primary or acquired drug resistance due to the overexpression of efflux pumps. A novel mechanism to circumvent this is to integrate drugs, such as anthracycline antibiotics, with nanoparticle delivery vehicles that can bypass intrinsic tumor drug-resistance mechanisms. DNA nanoparticles serve as an efficient binding platform for intercalating drugs (e.g. anthracyclines doxorubicin and daunorubicin, which are widely used to treat acute leukemias) and enable precise structure design and chemical modifications, for example for incorporating targeting capabilities. Here, we utilize DNA nanostructures to circumvent daunorubicin drug resistance at clinically relevant doses in a leukemia cell line model. We report the fabrication of a rod-like DNA origami drug carrier that can be controllably loaded with daunorubicin. We further directly verify that nanostructure-mediated daunorubicin delivery leads to increased drug entry and retention in cells relative to free daunorubicin at equal concentrations, which yields significantly enhanced drug efficacy. Our results indicate that DNA origami nanostructures can circumvent efflux pump-mediated drug resistance in leukemia cells at clinically relevant drug concentrations and provide a robust DNA nanostructure design that could be implemented in a wide range of cellular applications due to its remarkably fast self-assembly (~5 minutes) and excellent stability in cell culture conditions.

DNA origami (DO) nanotechnology enables the construction of precise nanostructures capable of functionalization with small molecule drugs, nucleic acids, and proteins, suggesting a promising platform for biomedical applications. Despite the potential for drug and vaccine delivery, the impact of DO vehicles on immunogenicity in vivo is not well understood. Here, two DO vehicles, a flat triangle and a nanorod, at varying concentrations are evaluated in vitro and with a repeated dosing regimen administered at a high dose in vivo to study early and late immunogenicity. The studies show normal CD11b+ myeloid cell populations preferentially internalize DO in vitro. DO structures distribute well systemically in vivo, elicit a modest pro‐inflammatory immune response that diminishes over time and are nontoxic as shown by weight, histopathology, lack of cytokine storm, and a complete biochemistry panel at the day 10 end point. The results take critical steps to characterize the biological response to DO and suggest that DO vehicles represent a promising platform for drug delivery and vaccine development where immunogenicity should be a key consideration.

Single molecule force spectroscopy is a powerful approach to probe the structure, conformational changes, and kinetic properties of biological and synthetic macromolecules. However, common approaches to apply forces to biomolecules require expensive and cumbersome equipment and relatively large probes such as beads or cantilevers, which limits their use for many environments and makes integrating with other methods challenging. Furthermore, existing methods have key limitations such as an inability to apply compressive forces on single molecules. We report a nanoscale DNA force spectrometer (nDFS), which is based on a DNA origami hinge with tunable mechanical and dynamic properties. The angular free energy landscape of the nDFS can be engineered across a wide range through substitution of less than 5% of the strand components. We further incorporate a removable strut that enables reversible toggling of the nDFS between open and closed states to allow for actuated application of tensile and compressive forces. We demonstrate the ability to apply compressive forces by inducing a large bend in a 249bp DNA molecule, and tensile forces by inducing DNA unwrapping of a nucleosome sample. These results establish a versatile tool for force spectroscopy and robust methods for designing nanoscale mechanical devices with tunable force application.

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DNA origami “Trojan horse” nanostructures provide an effective delivery approach to circumvent drug resistance in leukemia cells. These 100 nanometer delivery vehicles, described on page 308 by C. E. Castro and co‐workers, are easily fabricated in 10 min and can be precisely loaded with commonly used anthracycline chemotherapeutic drugs. Drug‐loaded DNA origami nanostructures enter cells via endocytosis, allowing the drug to bypass defenses in the cell membrane that are effective against free drug. This approach leads to larger amounts of drug in cells, which is later released due to decreasing pH and enzymatic degradation, ultimately improving drug efficacy.

DNA origami is a rapidly emerging nanotechnology that enables researchers to create nanostructures with unprecedented geometric precision that have tremendous potential to advance a variety of fields including molecular sensing, robotics, and nanomedicine. Hence, many students could benefit from exposure to basic knowledge of DNA origami nanotechnology. However, due to the complexity of design, cost of materials, and cost of equipment, experiments with DNA origami have been limited mainly to research institutions in graduate level laboratories with significant prior expertise and well-equipped laboratories. This work focuses on overcoming critical barriers to translating DNA origami methods to educational laboratory settings. In particular, we present a streamlined protocol for fabrication and analysis of DNA origami nanostructures that can be carried out within a 2-hour laboratory course using low-cost equipment, much of which is readily available in educational laboratories and science classrooms. We focus this educational experiment module on a DNA origami nanorod structure that was previously developed for drug delivery applications. In addition to fabricating nanostructures, we demonstrate a protocol for students to analyze structures via gel electrophoresis using classroom-ready gel equipment. These results establish a basis to expose students to DNA origami nanotechnology and can enable or reinforce valuable learning milestones in fields such as biomaterials, biological engineering, and nanomedicine. Furthermore, introducing students to DNA nanotechnology and related fields can also have the potential to increase interest and future involvement by young students.

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