Yingke_Wu

It is highly demanding to design active nanomotors that can move in response to specific signals with controllable rate and direction. A catalysis-driven nanomotor was constructed by designing catalytically and plasmonically active Janus gold nanoparticles (Au NPs), which generate an asymmetric temperature gradient of local solvent surrounding NPs in catalytic reactions. The self-thermophoresis behavior of the Janus nanomotor is monitored from its inherent plasmonic response. The diffusion coefficient of the self-thermophoresis motion is linearly dependent on chemical reaction rate, as described by a stochastic model.

Self-propulsion of a Janus plasmonic nanomotor is presented that is driven by a chemical reaction. The mechanism of self-phoretic motion is explained as self-thermophoresis, and a stochastic model was developed to describe the relation between the diffusion coefficients of self-thermophoresis motion with chemical reaction rate.

A newly developed polyacrylamide-co-methyl acrylate/spiropyran (SP) hydrogel crosslinked by SP mechanophore demonstrates multi-stimuli-responsive and mechanically strong properties. The hydrogels not only exhibit thermo-, photo-, and mechano-induced color changes, but also achieve super-strong mechanical properties (tensile stress of 1.45 MPa, tensile strain of ≈600%, and fracture energy of 7300 J m⁻²). Due to a reversible structural transformation between spiropyran (a ring-close) and merocyanine (a ring-open) states, simple exposure of the hydrogels to white light can reverse color changes and restore mechanical properties. The new design approach for a new mechanoresponsive hydrogel is easily transformative to the development of other mechanophore-based hydrogels for sensing, imaging, and display applications.

A newly developed poly(acrylamide-co-methyl acrylate)/spiropyran hydrogel with multi-stimuli-responsive and mechanically strong properties is presented. The resulting hydrogel exhibits reversible changes in color response and mechanical properties, making it promising for sensing, imaging, and display applications.

Synthetic transmembrane channels are rationally designed molecules that can transport ions by formation of nanopores that span the lipid bilayer, and provide an alternative strategy for the development of membrane-active antimicrobials. However, few such channels show membrane selectivity. In their Communication on page 2999 ff., J.-L. Hou and co-workers report a channel that is able to specifically insert into the lipid bilayers of Gram-positive bacteria but not into those of mammalian erythrocytes.

A thermoplastic high strain multishape memory polymer can be fabricated using a hemiphasmid side-chain polynorbornene (P1) with hexagonal columnar liquid crystalline (Φ_H) phase. Without any chemical crosslinks, P1 can memorize multiple temporary shapes with high strain and exhibit excellent shape fixity and shape recovery. As the building blocks of Φ_H, the multichain columns in P1 act as robust physical crosslinks.

Repair of damaged skeletal-muscle tissue is limited by the regenerative capacity of the native tissue. Current clinical approaches are not optimal for the treatment of large volumetric skeletal-muscle loss. As an alternative, tissue engineering represents a promising approach for the functional restoration of damaged muscle tissue. A typical tissue-engineering process involves the design and fabrication of a scaffold that closely mimics the native skeletal-muscle extracellular matrix (ECM), allowing organization of cells into a physiologically relevant 3D architecture. In particular, anisotropic materials that mimic the morphology of the native skeletal-muscle ECM, can be fabricated using various biocompatible materials to guide cell alignment, elongation, proliferation, and differentiation into myotubes. Here, an overview of fundamental concepts associated with muscle-tissue engineering and the current status of muscle-tissue-engineering approaches is provided. Recent advances in the development of anisotropic scaffolds with micro- or nanoscale features are reviewed, and how scaffold topographical, mechanical, and biochemical cues correlate to observed cellular function and phenotype development is examined. Finally, some recent developments in both the design and utility of anisotropic materials in skeletal-muscle-tissue engineering are highlighted, along with their potential impact on future research and clinical applications.

Muscle-tissue-engineering approaches are reviewed, focusing on anisotropic matrices, including micropatternered substrates, and aligned microporous and aligned fibrous scaffolds. Challenges associated with engineering aligned matrices are highlighted and correlation of scaffold topographical, mechanical, and biochemical cues to cellular function and myogenic phenotype development is discussed.

O. Lieleg and co-workers present a mortar hybrid material on page 8138, in which the biomineralization process is stimulated by adding a biological component, i.e., a bacterial biofilm, to standard mortar. This hybrid mortar, illustrated on the left side of the image, shows increased roughness and hydrophobicity compared to the standard mortar, which is depicted on the right side.

Polysaccharide-based hydrogels have multiple advantages because of their inherent biocompatibility, biodegradability, and non-toxicic properties. The feasibility of using polysaccharide-based hydrogels could be improved if they could simultaneously fulfill the mechanical property and cell compatibility requirements for practical applications. Herein, the construction of double-cross-linked (DC) cellulose hydrogels is described using sequential chemical and physical cross-linking, resulting in DC cellulose hydrogels that are mechanically superior to single-cross-linked cellulose hydrogels. The formation and spatial distribution of chemically cross-linked domains and physically cross-linked domains within the DC cellulose hydrogels are demonstrated. The molar ratio of epichlorohydrin to anhydroglucose units of cellulose and the concentration of the aqueous ethanol solution are two critical parameters for obtaining mechanically strong and tough DC cellulose hydrogels. The mechanical properties of the DC cellulose hydrogels under loading-unloading cycles are described using compression and tension models. The possible toughening mechanism of double-cross-linking is discussed.

Double-cross-linked (DC) cellulose hydrogels are fabricated by a sequential chemical and physical cross-linking strategy. The irreversible covalent cross-linkings, cellulose II crystallite hydrates, together with the chain entanglements and strong hydrogen bonding interactions between cellulose chains endow the DC cellulose hydrogels with high strength, high toughness, and good recoverability.

Shape-memory polymers (SMPs) are morphologically responsive materials with potential for a variety of biomedical applications, particularly as devices for minimally invasive surgery and the delivery of therapeutics and cells for tissue engineering. A brief introduction to SMPs is followed by a discussion of the current progress toward the development of SMP-based biomaterials for clinically relevant biomedical applications.

Stimuli-responsive shape-memory polymer-based materials have great potential for a variety of biomedical applications. Their development toward use as functional biomedical devices for drug delivery, minimally invasive surgery and tissue engineering are discussed, particularly with a view to their progress toward clinical relevance.

Dynamic crosslinking of extremely stretchable hydrogels with rapid self-healing ability is described. Using this new strategy, the obtained hydrogels are able to elongate 100 times compared to their initial length and to completely self-heal within 30 s without external energy input.

Photoswitchable azobenzene cross-linkers can control the folding and unfolding of peptides by photoisomerization and can thus regulate peptide affinities and enzyme activities. Using quantum mechanics/molecular mechanics (QM/MM) methods and classical MM force fields, we report the first molecular dynamics simulations of the photoinduced folding and unfolding processes in the azobenzene cross-linked FK-11 peptide. We find that the interactions between the peptide and the azobenzene cross-linker are crucial for controlling the evolution of the secondary structure of the peptide and responsible for accelerating the folding and unfolding events. They also modify the photoisomerization mechanism of the azobenzene cross-linker compared with the situation in vacuo or in solution.

Using quantum mechanics/molecular mechanics (QM/MM) and classical MM dynamics methods the photoinduced folding and unfolding of an azobenzene cross-linked peptide was simulated. The interaction between the peptide and the cross-linker plays a key role not only in regulating the photoinduced evolution of the secondary structure of the peptide, but also in tuning the photoisomerization mechanism of the azobenzene cross-linker.

Dynamically restructuring pH-responsive hydrogels are synthesized, employing dynamic covalent chemistry between phenylboronic acid and cis-diol modified poly(ethylene glycol) macromonomers. These gels display shear-thinning behavior, followed by a rapid structural recovery (self-healing). Size-dependent in vitro controlled and glucose-responsive release of proteins from the hydrogel network, as well as the biocompatibility of the gels, are evaluated both in vitro and in vivo.