Transfer of multi-DNA patches by colloidal stamping.

Patchy particles have received great attention due to their ability to develop directional and selective interactions and serve as building units for the self-assembly of innovative colloidal molecules and crystalline structures. Although synthesizing particles with multiple dissimilar patches is still highly challenging and lacks efficient methods, these building blocks would open paths towards a broader range of ordered materials with inherent properties. Herein, we describe a new approach to pattern functional DNA patches at the surface of particles, by the use of colloidal stamps.

Assembly of Anisotropic Nanocellulose Films Stronger than the Original Tree.

Natural structural materials frequently consist of multimaterial nanocomposites with complex superstructure giving rise to exceptional mechanical properties, but also commonly preventing access to their synthetic reproduction. Here we present the spin-assisted layer-by-layer assembly of anisotropic wood-inspired films composed of anionic cellulose nanofibrils and cationic poly(vinyl amine) possessing a tensile strength that exceeds that of the wood from which the fibers originate. The degree of orientation of the nanofibrils was studied by atomic force microscopy and depends strongly on the distance from the center of the spun surface.

Colloidal molecules and patchy particles: complementary concepts, synthesis and self-assembly.

This review describes the latest advances in the synthesis and assembly of specific colloids such as the colloidal molecules as defined by van Blaaderen in 2003 and the patchy particles imagined a few years later. The two concepts are closely related because some may serve as precursors of others and vice versa. To best mimic the molecular structures, it is necessary to introduce the notions of directed binding and valence which result in the concept of patches arranged on the particle surface according to the conventional repulsion figures.

Synthesis of Colloidal Molecules: Recent Advances and Perspectives.

The synthesis and study of colloidal molecules, that is to say clusters of a small number of colloidal entities that resemble the configuration of atoms in molecules both in constituent size and angular arrangement to that of valence shell electron pair repulsion model-related space-filling geometries, are of continued and significant interest. The rapid development in this research area has attracted intense interest from researchers with diverse expertise, and numerous methods towards the synthesis of colloidal molecules have been reported. In this Minireview, we attempt to give an overview of these latest developments, classifying them in processes based on controlled phase separation phenomena, on controlled surface nucleation and growth, and on controlled clustering.

Modular Design of Programmable Mechanofluorescent DNA Hydrogels.

Mechanosensing systems are ubiquitous in nature and control many functions from cell spreading to wound healing. Biologic systems typically rely on supramolecular transformations and secondary reporter systems to sense weak forces. By contrast, synthetic mechanosensitive materials often use covalent transformations of chromophores, serving both as force sensor and reporter, which hinders orthogonal engineering of their sensitivity, response and modularity.

Pathway-controlled formation of mesostructured all-DNA colloids and superstructures.

DNA has traditionally been used for the programmable design of nanostructures by exploiting its sequence-defined supramolecular recognition. However, control on larger length scales or even hierarchical materials that translate to the macroscale remain difficult to construct. Here, we show that the polymer character of single-stranded DNA (ssDNA) can be activated via a nucleobase-specific lower critical solution temperature, which provides a unique access to mesoscale structuring mechanisms on larger length scales.

Photonic Devices Out of Equilibrium: Transient Memory, Signal Propagation, and Sensing.

Soft photonic materials are important for sensors, displays, or energy management and have become switchable under static equilibrium conditions by integration of responsive polymer features. The next step is to equip such materials with the ability for autonomously dynamic and self-regulating behavior, which would advance their functionality and application possibilities to new levels. Here, this study shows the system integration of a nonlinear, biocatalytic pH-feedback system with a pH-responsive block copolymer photonic gel, and demonstrates autonomous transient memories, remotely controlled signal propagation, and sensing.

Materials learning from life: concepts for active, adaptive and autonomous molecular systems.

Bioinspired out-of-equilibrium systems will set the scene for the next generation of molecular materials with active, adaptive, autonomous, emergent and intelligent behavior. Indeed life provides the best demonstrations of complex and functional out-of-equilibrium systems: cells keep track of time, communicate, move, adapt, evolve and replicate continuously. Stirred by the understanding of biological principles, artificial out-of-equilibrium systems are emerging in many fields of soft matter science.

Light-Adaptive Supramolecular Nacre-Mimetic Nanocomposites.

Nature provides design paradigms for adaptive, self-healing, and synergistic high-performance structural materials. Nacre's brick-and-mortar architecture is renowned for combining stiffness, toughness, strength, and lightweightness. Although elaborate approaches exist to mimic its static structure and performance, and to incorporate functionalities for the engineering world, there is a profound gap in addressing adaptable mechanical properties, particularly using remote, quick, and spatiotemporal triggers.

Supramolecular Engineering of Hierarchically Self-Assembled, Bioinspired, Cholesteric Nanocomposites Formed by Cellulose Nanocrystals and Polymers.

Natural composites are hierarchically structured by combination of ordered colloidal and molecular length scales. They inspire future, biomimetic, and lightweight nanocomposites, in which extraordinary mechanical properties are in reach by understanding and mastering hierarchical structure formation as tools to engineer multiscale deformation mechanisms. Here we describe a hierarchically self-assembled, cholesteric nanocomposite with well-defined colloid-based helical structure and supramolecular hydrogen bonds engineered on the molecular level in the polymer matrix.

Bioinspired Mechanical Gradients in Cellulose Nanofibril/Polymer Nanopapers.

Mechanical gradients are important as tough joints, for strain field engineering in printable electronics, for actuators, and for biological studies, yet they are difficult to prepare and quantitatively characterize. We demonstrate the additive fabrication of gradient bioinspired nanocomposites based on stiff, renewable cellulose nanofibrils that are bottom-up toughened via a tailor-made copolymer. Direct filament writing of different nanocomposite hydrogels in patterns, and subsequent healing of the filaments into continuous films while drying leads to a variety of linear, parabolic and striped bulk gradients.

Layer-by-Layer assembled growth factor reservoirs for steering the response of 3T3-cells.

Layer-by-Layer (LbL) assemblies of heparin (Hep) and chitosan (Chi) were prepared for use as reservoirs for acidic and basic fibroblast growth factors (aFGFs and bFGFs, respectively). The effects of the architecture and composition of the reservoirs on the viability and proliferation of NIH-3T3 fibroblast cells were studied under starvation conditions. The reservoir stability was monitored by ellipsometry.

Bio-inspired multiproperty materials: strong, self-healing, and transparent artificial wood nanostructures.

Nanocomposite films possessing multiple interesting properties (mechanical strength, optical transparency, self-healing, and partial biodegradability) are discussed. We used Layer-by-Layer assembly to prepare micron thick wood-inspired films from anionic nanofibrillated cellulose and cationic poly(vinyl amine). The film growth was carried out at different pH values to obtain films of different chemical composition, whereby, and as expected, higher pH values led to a higher polycation content and also to 6 times higher film growth increments (from 9 to 55 nm per layer pair).