DNA-derived nanostructures selectively capture gram-positive bacteria

We report the first demonstration of the efficient bacteria targeting properties of DNA-based polymeric micelles with high-density DNA corona. Nanoscale polymer micelles derived from DNA-b-polystyrene (DNA-b-PS) efficiently selected most tested Gram-positive strains over Gram-negative strains; single-strand DNAs were 20-fold less selective. We demonstrate that these targeting properties were derived from the interaction between densely packed DNA strands of the micelle corona and the peptidoglycan layers of Gram-positive bacteria. DNA-b-PS micelles incorporating magnetic nanoparticles (MNPs) can efficiently capture and concentrate Gram-positive bacteria suggesting the simple applications of these DNA block copolymer micelles for concentrating bacteria. Adenine (A), thymine (T), cytosine (C), and guanine (G)-rich nanostructures were fabricated, respectively, for investigating the effect of sequence on Gram-selective bacteria targeting. T-rich micelles showed the most efficient targeting properties. The targeting properties of these DNA nanostructures toward Gram-positive bacteria may have applications as a targeted therapeutic delivery system.

Expanding the materials space of DNA via organic-phase ring-opening metathesis polymerization

Herein, we develop a facile route to bring DNA to the organic phase, which greatly expands the types of structures accessible using DNA macromonomers. Phosphotriester- and exocyclic amine-protected DNA was synthesized and further modified with a norbornene moiety, which enables homopolymerization via ring-opening metathesis to produce brush-type DNA graft polymers in high yields. Subsequent deprotection cleanly reveals the natural phosphodiester DNA. The method not only achieves high molecular weight DNA graft polymers but when carried out at low monomer:catalyst ratios, yields oligomers that can be further fractionated to molecularly pure, monodisperse entities with one through ten DNA strands per molecule. In addition, we demonstrate substantial simplification in the preparation of traditionally difficult DNA-containing structures, such as DNA/poly(ethylene glycol) diblock graft copolymers and DNA amphiphiles. We envision that the marriage of oligonucleotides with the vast range of organic-phase polymerizations will result in many new classes of materials with yet unknown properties.

Self-assembly of DNA-based Nanomaterials and Potential Application in Drug Delivery

DNA can be self-assembled into programmable two-dimensional and three-dimensional nanoarchitectures with arbitrarily predetermined sizes and shapes. Because of the addressable arbitrary size and shape, great capacity of cargo loading, ability to be internalized by cells, the stability of structures under physiological conditions and excellent biocompatibility, the pristine DNA nanostructures are explored as drug vehicles in drug delivery. In addition, DNA block copolymer and DNADendron hybrid, as new building blocks, can be self-assembled into different kinds of ordered structures, e.g., nanofibers, spherical micelles, and vesicles, in aqueous solution. Recent studies have shown that some of these nanostructures could easily enter cells with excellent cell uptake efficiency. Herein, this review will mainly introduce the self-assembly behavior of pristine DNA and DNA hybrid materials including DNA block copolymers and DNA-Dendron hybrids, and their application in drug delivery.