The study of the conformation properties of macromolecules is at the heart of polymer science. Essentially all physical properties of polymers are manifestations of the underlying polymer ...conformations or otherwise significantly impacted by the conformation properties. In this Perspective, we review some of the key concepts that we have learned over nearly eight decades of the subject and outline some open questions. The topics include both familiar subjects in polymer physics textbooks and more recent results or not-so-familiar subjects, such as non-Gaussian chain behavior in polymer melts and topological effects in ring polymers. The emphasis is on understanding the key concepts, with both physical reasoning and mathematical analysis, and on the interconnection between the different results and concepts.
The recent decades have seen a surge of new nanomaterials designed for efficient drug delivery. DNA nanotechnology has been developed to construct sophisticated 3D nanostructures and artificial ...molecular devices that can be operated at the nanoscale, giving rise to a variety of programmable functions and fascinating applications. In particular, DNA‐origami nanostructures feature rationally designed geometries and precise spatial addressability, as well as marked biocompatibility, thus providing a promising candidate for drug delivery. Here, the recent successful efforts to employ self‐assembled DNA‐origami nanostructures as drug‐delivery vehicles are summarized. The remaining challenges and open opportunities are also discussed.
Structural DNA nanotechnology provides a biocompatible platform to construct customized nanocarriers. Recent developments of DNA‐origami‐based drug‐delivery systems are summarized. Multifunctional, highly tunable, and biologically amenable, DNA‐based nanomaterials will provide powerful strategies to understand and treat disease.
DNA origami has been widely investigated as a template for the organization of various functional elements, leading to potential applications in many fields such as biosensing, nanoelectronics, and ...nanophotonics. However, the synthesis of inorganic nonmetallic nanomaterials with predesigned patterns using DNA origami templates has seldom been explored. Here, a novel method is reported to site‐specifically synthesize silica nanostructures with designed patterns on DNA origami templates. The molecular dynamic simulation confirms that the positively charged silica precursors have a stronger electrostatic affinity to protruding double‐stranded DNA (dsDNA) than DNA origami surfaces. The work describes a novel strategy to fabricate silica nanostructures with nanoscale precision. Moreover, the site‐specific silicification of DNA nanoarchitectures expands the scope of customized synthesis of inorganic nonmetallic nanomaterials.
Arbitrary silica nanopatterns are fabricated on DNA origami templates by rationally designing the protruding double‐stranded DNA (dsDNA) arrays as nucleation sites. Molecular dynamic simulation confirms that the positively charged silica precursors have a stronger electrostatic affinity to protruding dsDNA than DNA origami surfaces. The site‐specific silicification of DNA nanoarchitectures expands the scope of customized synthesis of inorganic nonmetallic nanomaterials.
Metallic bowtie nanoarchitectures can produce dramatic electric field enhancement, which is advantageous in single‐molecule analysis and optical information processing. Plasmonic bowtie ...nanostructures were successfully constructed using a DNA origami‐based bottom‐up assembly strategy, which enables precise control over the geometrical configuration of the bowtie with an approximate 5 nm gap. A single Raman probe was accurately positioned at the gap of the bowtie. Single‐molecule surface‐enhanced Raman scattering (SM‐SERS) of individual nanostructures, including ones containing an alkyne group, was observed. The design achieved repeatable local field enhancement of several orders of magnitude. This method opens the door on a novel strategy for the fabrication of metal bowtie structures and SM‐SERS, which can be utilized in the design of highly‐sensitive photonic devices.
Plasmonic bowtie nanostructures were successfully constructed using DNA origami‐based self‐assembly. A single Raman probe was accurately positioned at the gap of the bowtie and single‐molecule SERS of individual nanostructures was observed.
The unprecedented development of DNA nanotechnology has caused DNA self‐assembly to attract close attention in many disciplines. In this research news article, the employment of DNA self‐assembly in ...the fields of materials science and nanotechnology is described. DNA self‐assembly can be used to prepare bulk‐scale hydrogels and 3D macroscopic crystals with nanoscale internal structures, to induce the crystallization of nanoparticles, to template the fabrication of organic conductive nanomaterials, and to act as drug delivery vehicles for therapeutic agents. The properties and functions are fully tunable because of the designability and specificity of DNA assembly. Moreover, because of the intrinsic dynamics, DNA self‐assembly can act as a program switch and can efficiently control stimuli responsiveness. We highlight the power of DNA self‐assembly in the preparation and function regulation of materials, aiming to motivate future multidisciplinary and interdisciplinary research. Finally, we describe some of the challenges currently faced by DNA assembly that may affect the functional evolution of such materials, and we provide our insights into the future directions of several DNA self‐assembly‐based nanomaterials.
This article discusses the significant roles of DNA self‐assembly in materials science and nanotechnology, including the formation of hydrogels, induced three‐dimensional crystallization, the templated synthesis of conductive polymers, and nanomedical vehicles. In particular, the designability, specific recognition, and inherent dynamics enable DNA self‐assemblies to be the key elements in regulating the functions of DNA‐based bulk‐scale and nanoscale materials.
The efficient delivery of a therapeutic gene into target tissues has remained a major obstacle in realizing a viable gene-based medicine. Herein, we introduce a facile and universal strategy to ...construct a DNA nanostructure-based codelivery system containing a linear tumor therapeutic gene (p53) and a chemotherapeutic drug (doxorubicin, DOX) for combined therapy of multidrug resistant tumor (MCF-7R). This novel codelivery system, which is structurally similar to a kite, is rationally designed to contain multiple functional groups for the targeted delivery and controlled release of the therapeutic cargoes. The self-assembled DNA nanokite achieves efficient gene delivery and exhibits effective inhibition of tumor growth in vitro and in vivo without apparent systemic toxicity. These structurally and chemically well-defined codelivery nanovectors provide a new platform for the development of gene therapeutics for not only cancer but also a wide range of diseases.
We perform a general thermodynamic analysis for the salt partitioning behavior in the coexisting phases for symmetric mixtures of polycation and polyanion solutions. We find that salt partitioning is ...determined by the competition between two factors involving the ratio of the polyelectrolyte concentration in the coacervate phase to that in the supernatant phase and the difference in the exchange excess chemical potential Δμexthe excess chemical potential difference between PE segments and small ionsbetween the coexisting phases. The enrichment of salt ions in the coacervate phase predicted by the Voorn–Overbeek theory is shown to arise from its neglect of chain connectivity in the excess free energy which results in Δμex = 0 under all conditions. We argue that chain connectivity in general leads to a finite value of Δμex, which decreases with increasing PE concentration. Explicit calculations using theories that include the chain connectivity correlationsa simple liquid-state theory and a renormalized Gaussian fluctuation theoryshow nonmonotonic behavior of the salt-partitioning coefficient (the ratio of salt ion concentration in the coacervate phase to that in the supernatant phase): it is larger than 1 at very low salt concentrations, reaches a minimum at some intermediate salt concentration, and approaches 1 at the critical point. This behavior is consistent with recent computer simulation and experimental results.
Enzymes tend to malfunction when they work out of their natural cellular environments. Engineering a favorable microenvironment around enzymes has emerged as an effective strategy to finely tune the ...enzymatic functions and reshape the biocatalytic activities. Supramolecular self‐assembly provides a bottom‐up approach for spatial arrangement of functional groups and fabrication of materials with tailorable local properties. In this review, the progress in designing, creating, and tailoring the enzyme microenvironments is discussed, with the bioinspired self‐assembling materials as the scaffolds built from molecular building blocks. The relationship between the physicochemical properties and the local environments (pH, substrates, or hydration) of the scaffolds, and the catalytic properties of the scaffolded enzymes are focused upon. The power of the self‐assembly to regulate the catalytic systems dynamically is also highlighted. In the end, an outlook on the obstacles, possible solutions, and future directions on the microenvironment engineering of enzymes is provided.
The supramolecular scaffolds that are self‐assembled by molecular building blocks (DNA, peptides/proteins, or amphiphilic block copolymers) have tailorable microenvironments (local pH, substrate confinement, or local hydration), allowing the catalytic functions of the scaffolded enzymes to be modulated.
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