Molecular Additives as Competitive Binding Agents to Control Supramolecular-Driven Nanoparticle Assembly.

Colloidal nanoparticle assembly methods can produce intricate superlattice structures and often use knowledge of atomic crystallization behaviors to guide their design. While this analogy has enabled multiple routes to programming colloidal crystallization thermodynamics, fewer tools or strategies exist to manipulate nanoparticle superlattice growth kinetics in a controlled manner. Here we investigate how small-molecule additives can be used to modulate the thermodynamics and kinetics of supramolecular-chemistry-driven nanoparticle assembly.

Scoring System Assessing Risks of Growth in Sporadic Vestibular Schwannoma.

Background And Objectives: Surveillance studies offer sparse knowledge of predictors of future growth in sporadic vestibular schwannomas (VS).Our aim was identification of these risk factors. We propose a scoring system to estimate the risk of growth in sporadic vestibular schwannoma.

Controlling the thermally-driven crystallization of DNA-coated nanoparticles with formamide.

DNA-coated nanoparticles, also known as programmable atom equivalents (PAEs), facilitate the construction of materials with nanoscopic precision. Thermal annealing plays a pivotal role by controlling DNA hybridization kinetics and thermodynamics, which ensures the formation of intended structures. While various design handles such as particle size, DNA design, and salt concentration influence the stability of the DNA duplexes linking PAEs in a lattice, their influence on the system's melting temperature () often follows complicated trends that make rational tuning of self-assembly challenging.

Nanoparticle Superlattices with Nonequilibrium Crystal Shapes.

Nanoparticle assembly is a material synthesis strategy that enables precise control of nanoscale structural features. Concepts from traditional crystal growth research have been tremendously useful in predicting and programming the unit cell symmetries of these assemblies, as their thermodynamically favored structures are often identical to atomic crystal analogues. However, these analogies have not yielded similar levels of influence in programming crystallite shapes, which are a consequence of both the thermodynamics and kinetics of crystal growth.

Nanocrystal Assemblies: Current Advances and Open Problems.

We explore the potential of nanocrystals (a term used equivalently to nanoparticles) as building blocks for nanomaterials, and the current advances and open challenges for fundamental science developments and applications. Nanocrystal assemblies are inherently multiscale, and the generation of revolutionary material properties requires a precise understanding of the relationship between structure and function, the former being determined by classical effects and the latter often by quantum effects. With an emphasis on theory and computation, we discuss challenges that hamper current assembly strategies and to what extent nanocrystal assemblies represent thermodynamic equilibrium or kinetically trapped metastable states.

Rationally Designing the Supramolecular Interfaces of Nanoparticle Superlattices with Multivalent Polymers.

In supramolecular materials, multiple weak binding groups can act as a single collective unit when confined to a localized volume, thereby producing strong but dynamic bonds between material building blocks. This principle of multivalency provides a versatile means of controlling material assembly, as both the number and the type of supramolecular moieties become design handles to modulate the strength of intermolecular interactions. However, in materials with building blocks significantly larger than individual supramolecular moieties (e.

Controlling Colloidal Crystal Nucleation and Growth with Photolithographically Defined Templates.

Colloidal crystallization provides a means to synthesize hierarchical nanostructures by design and to use these complex structures for nanodevice fabrication. In particular, DNA provides a means to program interactions between particles with high specificity, thereby enabling the formation of particle superlattice crystallites with tailored unit cell geometries and surface faceting. However, while DNA provides precise control of particle-particle bonding interactions, it does not inherently present a means of controlling higher-level structural features such as the size, shape, position, or orientation of a colloidal crystallite.

Ultrafast dense DNA functionalization of quantum dots and rods for scalable 2D array fabrication with nanoscale precision.

Scalable fabrication of two-dimensional (2D) arrays of quantum dots (QDs) and quantum rods (QRs) with nanoscale precision is required for numerous device applications. However, self-assembly-based fabrication of such arrays using DNA origami typically suffers from low yield due to inefficient QD and QR DNA functionalization. In addition, it is challenging to organize solution-assembled DNA origami arrays on 2D device substrates while maintaining their structural fidelity.

Nanoparticle Brushes: Macromolecular Ligands for Materials Synthesis.

ConspectusColloidal nanoparticles have unique attributes that can be used to synthesize materials with exotic properties, but leveraging these properties requires fine control over the particles' interactions with one another and their surrounding environment. Small molecules adsorbed on a nanoparticle's surface have traditionally served as ligands to govern these interactions, providing a means of ensuring colloidal stability and dictating the particles' assembly behavior. Alternatively, nanoscience is increasingly interested in instead using macromolecular ligands that form well-defined polymer brushes, as these brushes provide a much more tailorable surface ligand with significantly greater versatility in both composition and ligand size.

Tunable Mechanical Response of Self-Assembled Nanoparticle Superlattices.

Self-assembled nanoparticle superlattices (NPSLs) are an emergent class of self-architected nanocomposite materials that possess promising properties arising from precise nanoparticle ordering. Their multiple coupled properties make them desirable as functional components in devices where mechanical robustness is critical. However, questions remain about NPSL mechanical properties and how shaping them affects their mechanical response.

Reversible Diffusionless Phase Transitions in 3D Nanoparticle Superlattices.

Nanocomposite tectons (NCTs), polymer brush-grafted nanoparticles that use supramolecular interactions to drive their assembly, form ordered nanoparticle superlattices (NPSLs) with well-defined unit cell symmetries when thermally annealed. In this work, we demonstrate that appropriate assembly and processing conditions can also enable control over the microstructure of NCT lattices by balancing the enthalpic and entropic factors associated with ligand packing and supramolecular bonding during crystallization. Unary systems of NCTs are assembled via the addition of a small molecule capable of binding to multiple nanoparticle ligands; these NCTs initially form face-centered-cubic (FCC) structures in solvents that are favorable for the particles' polymer brushes.

Improving nanoparticle superlattice stability with deformable polymer gels.

The self-assembly of colloidal nanoparticles into ordered superlattices typically uses dynamic interactions to govern particle crystallization, as these non-permanent bonds prevent the formation of kinetically trapped, disordered aggregates. However, while the use of reversible bonding is critical in the formation of highly ordered particle arrangements, dynamic interactions also inherently make the structures more prone to disassembly or disruption when subjected to different environmental stimuli. Thus, there is typically a trade-off between the ability to initially form an ordered colloidal material and the ability of that material to retain its order under different conditions.

Self-Assembling Systems for Optical Out-of-Plane Coupling Devices.

Micromirrors are used in integrated photonics to couple extraplanar light into the planar structure of a device by redirecting light via specular reflection. Compared with grating or prism-based couplers, micromirrors allow for coupling of light over a broader range of wavelengths, provided that the micromirror is fabricated with a specific 3D shape to ensure proper reflection angles. In principle, self-assembly methods could enable reliable, parallelizable fabrication of such devices with a high degree of precision by designing self-assembling components that produce the desired microscale geometry as their thermodynamic products.

A 2 and 5-Year Longitudinal Analysis of 671 Consecutive Patients Diagnosed with Unilateral Vestibular Schwannoma.

Objective: To analyse the 2 and 5-year outcomes of a cohort of patients with newly diagnosed vestibular schwannoma patients.

Study Design: Longitudinal cohort study.

Setting: Tertiary skull base referral unit.

Controlling the dynamics of elastomer networks with multivalent brush architectures.

Herein, we report a design strategy for developing mechanically enhanced and dynamic polymer networks by incorporating a polymer with multivalent brush architecture. Different ratios of two types of imidazole functionalized polymers, specifically poly(-butyl acrylate) (PnBA) and poly(poly(-butyl acrylate)) (PPnBA) were blended with Zn(II) ions, thereby forming a series of elastomers with consistent composition but varying network topologies. As the weight fraction of PPnBA increased, the melting temperature, plateau modulus, and relaxation time of the melt increased because of the increase in the crosslinking density and coordination efficiency.

Polymer Grafted Nanoparticle Composites with Enhanced Thermal and Mechanical Properties.

The distribution of filler particles within a polymer matrix nanocomposite has a profound influence on the properties and processability of the material. While filler aggregation and percolation can significantly enhance particular functionalities such as thermal and electrical conductivity, the formation of larger filler clusters and networks can also impair mechanical properties like strength and toughness and can also increase the difficulty of processing. Here, a strategy is presented for the preparation of functional composites that enhance thermal conductivity over polymer alone, without negatively affecting mechanical performance or processability.

Nanocomposite tectons as unifying systems for nanoparticle assembly.

Nanocomposite tectons (NCTs) are nanocomposite building blocks consisting of nanoparticle cores functionalized with a polymer brush, where each polymer chain terminates in a supramolecular recognition group capable of driving particle assembly. Like other ligand-driven nanoparticle assembly schemes (for example those using DNA-hybridization or solvent evaporation), NCTs are able to make colloidal crystal structures with precise particle organization in three dimensions. However, despite the similarity of NCT assembly to other methods of engineering ordered particle arrays, the crystallographic symmetries of assembled NCTs are significantly different.

Nanoparticle Assembly as a Materials Development Tool.

Nanoparticle assembly is a complex and versatile method of generating new materials, capable of using thousands of different combinations of particle size, shape, composition, and ligand chemistry to generate a library of unique structures. Here, a history of particle self-assembly as a strategy for materials discovery is presented, focusing on key advances in both synthesis and measurement of emergent properties to describe the current state of the field. Several key challenges for further advancement of nanoparticle assembly are also outlined, establishing a roadmap of critical research areas to enable the next generation of nanoparticle-based materials synthesis.

Crosslinking of Pressure-Sensitive Adhesives with Polymer-Grafted Nanoparticles.

Nanocomposite filler particles provide multiple routes to mechanically reinforce pressure-sensitive adhesives (PSAs), as their large surface area to volume ratios provide a means of effectively crosslinking multiple polymer chains. A major advancement could therefore be enabled by the design of a particle architecture that forms multiple physical and chemical interactions with the surrounding polymer matrix, while simultaneously ensuring particle dispersion and preventing particle aggregation. Understanding how such multivalent interactions between a nanoparticle crosslinking point and the PSA polymer affect material mechanical performance would provide both useful scientific knowledge on the mechanical structure-property relationships in polymer composites, as well as a new route to synthesizing useful PSA materials.

Compression neuropathies of the forearm: anatomy, clinical features and management.

The upper limb consists of four major parts: a girdle formed by the clavicle and scapula, the arm, the forearm and the hand. Peripheral nerve lesions of the upper limb are divided into lesions of the brachial plexus or the nerves arising from it. Lesions of the nerves arising from the brachial plexus are further divided into upper (proximal) or lower (distal) lesions based on their location.

Nanoparticle Assembly in High Polymer Concentration Solutions Increases Superlattice Stability.

Polymer nanocomposites are made by combining a nanoscale filler with a polymer matrix, where polymer-particle interactions can enhance matrix properties and introduce behaviors distinct from either component. Manipulating particle organization within a composite potentially allows for better control over polymer-particle interactions, and the formation of ordered arrays can introduce new, emergent properties not observed in random composites. However, self-assembly of ordered particle arrays typically requires weak interparticle interactions to prevent kinetic traps, making these assemblies incompatible with most conventional processing techniques.

Design and Synthesis of Quick Setting Nonswelling Hydrogels via Brush Polymers.

Brush polymers have emerged as components of novel materials that show huge potential in multiple disciplines and applications, including self-assembling photonic crystals, drug delivery vectors, biomimetic lubricants, and ultrasoft elastomers. However, an understanding of how this unique topology can affect the properties of highly solvated materials like hydrogels remain under investigated. Here, it is investigated how the high functionality and large overall size of brush polymers enhances the gelation kinetics of low polymer weight percent gels, enabling 100-fold faster gelation rates and 15-fold higher stiffness values than gels crosslinked by traditional star polymers of the same composition and polymer chain length.