Viscoelastic Mechanics: From Pathology and Cell Fate to Tissue Regeneration Biomaterial Development.

Viscoelasticity is the mechanical feature of living tissues and the cellular extracellular matrix (ECM) and has been recognized as an essential biophysical cue in cell function and fate regulation, tissue development and homeostasis maintenance, and disease progression. These findings provide new insights for the development of biomaterials with comparable viscoelastic properties as native ECMs and the tissue matrix, displaying promising applications in regeneration medicine. In this review, the relationship between matrix viscoelasticity and tissue functions (e.

pH-Responsive Polyglycerol Nanogels for Periodontitis Treatment through Antibacterial and Pro-Angiogenesis Action.

Periodontitis is a microbe-driven inflammatory disease leading to bone resorption and tissue destruction. We propose a dual-functional nanogel complex armed with the antimicrobial drug triclosan (TCS) and the pro-angiogenesis medication deferoxamine (DFO) for combating microbial pathogens and promoting tissue regeneration. The nanogel system (NG-TCS-DFO) that we fabricated from linear polyglycerol exhibits well-defined spherical morphology and a positively charged surface for bacteria adhesion.

Dopamine and alkylated silica functionalized Janus gauze with fluid control capability for rapid hemostasis.

Hemorrhage caused by trauma is a global public health issue. While traditional cotton gauze compression is commonly used for hemostasis, its efficacy is limited in severe hemorrhage cases. Herein, we developed a gauze with Janus wettability (JW-G).

Engineering Biodegradable Polyurethanes with Precisely Controlled Hierarchical Structures to Access Shape Memory Effect and Enhanced Bioactivities.

Biodegradable polymers with shape memory effects (SMEs) offer promising solutions for short-term medical interventions, facilitating minimally invasive procedures and subsequent degradation without requiring secondary surgeries. However, achieving a good balance among desirable SMEs, mechanical performance, degradation rate, and bioactivities remains a significant challenge. To address this issue, we established a strategy to develop a versatile biodegradable polyurethane (PPDO-PLC) with tunable hierarchical structures via precise chain segment control.

A supramolecular approach for converting renewable biomass into functional materials.

The rational transformation and utilization of biomass have attracted increasing attention because of its high importance in sustainable development and green economy. In this study, we used a supramolecular approach to convert biomass into functional materials. Six biomass raw materials with distinct chemical structures and physical properties were copolymerized with thioctic acid (TA) to afford poly[TA-biomass]s.

Host-Guest-Interaction Enhanced Nitric Oxide Photo-Generation within a Pillar[5]arene Cavity for Antibacterial Gas Therapy.

Supramolecular macrocycles with intrinsic cavities have been widely explored as containers to fabricate versatile functional materials specific host-guest recognitions. However, relatively few studies have focused on the modulation of guest reactivity within a macrocyclic cavity. Here, we demonstrate the confinement effect of pillar[5]arene with an electron-rich and precise cavity that can dramatically enhance guest photoactivity and nitric oxide (NO) generation upon visible light irradiation.

Shape Memory Polyester Scaffold Promotes Bone Defect Repair through Enhanced Osteogenic Ability and Mechanical Stability.

Bone tissue engineering involving scaffolds is recognized as the ideal approach for bone defect repair. However, scaffold materials exhibit several limitations, such as low bioactivity, less osseointegration, and poor processability, for developing bone tissue engineering. Herein, a bioactive and shape memory bone scaffold was fabricated using the biodegradable polyester copolymer's four-dimensional fused deposition modeling.

Functionalized Virus Nanoparticles Alleviates Osteoporosis via Targeting the Function of RANK-Specific Motifs.

Osteoporosis is a common skeletal disease characterized by excessive osteoclast-induced bone loss. RANKL/RANK signaling pathway is essential for osteoclastogenesis and is a key target for osteoporosis. However, regarding the fact that RANKL/RANK also functions beyond bone, the total block of RANKL/RANK will have unwanted impact on other organs.

Engineered Plant Virus Complexes with a RANK Motif Modulator and Bone Targeting for Osteoporosis Treatment.

Osteoporosis is a systemic skeletal disorder characterized by excessive osteoclastic bone resorption and impaired osteoblastic bone formation. Traditional delivery of antiresorptive drugs lacks a specific biodistribution in the body and may cause adverse effects to the patients. In this study, the peptide BTRM is first synthesized consisting of the bone-targeting peptide Asp8 (BT) and the peptide derived from the amino acid sequences of RANK Motif2/3 (RM), two cytoplasmic RANK motifs (PVQEET and PVQEQG) that have been reported to play an important role in osteoclastogenesis.

Multivalent non-covalent interactions lead to strongest polymer adhesion.

Multivalent interactions play a leading role in biological processes such as the inhibition of inflammation or virus internalization. The multivalent interactions show enhanced strength and better selectivity compared to monovalent interactions, but they are much less understood due to their complexity. Here, we detect molecular interactions in the range of a few piconewtons to several nanonewtons and correlate them with the formation and subsequent breaking of one or several bonds and assign these bonds.

Chemically defined stem cell microniche engineering by microfluidics compatible with iPSCs' growth in 3D culture.

The development of induced pluripotent stem cell (iPSCs) has opened unprecedented opportunities for biomedical applications, but poorly defined animal-derived matrices yield cells with limited therapeutic value. Considerable challenges remain in improving cell-culturing approaches to create the conditions for iPSCs' reliable expansion. Herein we report the development of a chemically defined, artificial three-dimensional (3D) microniche for iPSCs' growth and reliable expansion, constructed with degradable polyethyleneglycol-co-polycaprolactone and RGDfk-functionalized dendritic polyglycerol precursors according to bioorthogonal strain-promoted azide-alkyne cycloaddition by droplet-based microfluidics.

Hydrophobicity of Self-Assembled Monolayers of Alkanes: Fluorination, Density, Roughness, and Lennard-Jones Cutoffs.

The interplay of fluorination and structure of alkane self-assembled monolayers and how these affect hydrophobicity are explored via molecular dynamics simulations, contact angle goniometry, and surface-enhanced infrared absorption spectroscopy. Wetting coefficients are found to grow linearly in the monolayer density for both alkane and perfluoroalkane monolayers. The larger contact angles of monolayers of perfluorinated alkanes are shown to be primarily caused by their larger molecular volume, which leads to a larger nearest-neighbor grafting distance and smaller tilt angle.

"Raspberry" Hierarchical Topographic Features Regulate Human Mesenchymal Stem Cell Adhesion and Differentiation via Enhanced Mechanosensing.

An understanding of cellular mechanoresponses to well-defined synthetic topographic features is crucial for the fundamental research and biomedical applications of stem cells. Structured biointerfaces, in particular the ones with nanometer and/or micrometer surficial features, have drawn more attention in the past few decades. However, it is still difficult to integrate nanostructures and microstructures onto the synthesized biointerfaces to mimic the hierarchical architecture of the native extracellular matrix (ECM).

Well-Defined Nanostructured Biointerfaces: Strengthened Cellular Interaction for Circulating Tumor Cells Isolation.

The topographic features at the cell-material biointerface are critical for cellular sensing of the extracellular environment (ECM) and have gradually been recognized as key factors that regulate cell adhesion behavior. Herein, a well-defined nanostructured biointerface is fabricated via a new generation of mussel-inspired polymer coating to mimic the native ECM structures. Upon the bioinert background presence and biospecific ligands conjugation, the affinity of cancer cells to the resulting biofunctional surfaces, which integrate topographic features and biochemical cues, is greatly strengthened.

Controllable ligand spacing stimulates cellular mechanotransduction and promotes stem cell osteogenic differentiation on soft hydrogels.

Hydrogels with tunable mechanical properties have provided a tremendous opportunity to regulate stem cell differentiation. Hydrogels with osteoid (about 30-40 kPa) or higher stiffness are usually required to induce the osteogenic differentiation of mesenchymal stem cells (MSCs). It is yet difficult to achieve the same differentiation on very soft hydrogels, because of low environmental mechanical stimuli and restricted cellular mechanotransduction.

Self-Strengthening Adhesive Force Promotes Cell Mechanotransduction.

The extracellular matrix (ECM) undergoes dynamic remodeling and progressive stiffening during tissue regeneration and disease progression. However, most of the artificial ECMs and in vitro disease models are mechanically static. Here, a self-strengthening polymer coating mimicking the dynamic nature of native ECM is designed to study the cellular response to dynamic biophysical cues and promote cell mechanical sensitive response.

Ligand Diffusion Enables Force-Independent Cell Adhesion via Activating α5β1 Integrin and Initiating Rac and RhoA Signaling.

Cells reside in a dynamic microenvironment in which adhesive ligand availability, density, and diffusivity are key factors regulating cellular behavior. Here, the cellular response to integrin-binding ligand dynamics by directly controlling ligand diffusivity via tunable ligand-surface interactions is investigated. Interestingly, cell spread on the surfaces with fast ligand diffusion is independent of myosin-based force generation.

Surface Roughness Gradients Reveal Topography-Specific Mechanosensitive Responses in Human Mesenchymal Stem Cells.

The topographic features of an implant, which mechanically regulate cell behaviors and functions, are critical for the clinical success in tissue regeneration. How cells sense and respond to the topographical cues, e.g.

Surface Roughness and Substrate Stiffness Synergize To Drive Cellular Mechanoresponse.

Material surface topographic features have been shown to be crucial for tissue regeneration and surface treatment of implanted devices. Many biomaterials were investigated with respect to the response of cells on surface roughness. However, some conclusions even conflicted with each other due to the unclear interplay of surface topographic features and substrate elastic features as well as the lack of mechanistic studies.

Photoregulating Antifouling and Bioadhesion Functional Coating Surface Based on Spiropyran.

Dynamic regulation of the interactions between specific molecules on functional surfaces and biomolecules, for example, proteins or cells, is critical for biosensor and biomedical devices. Herein, we present a spiropyran (SP)-based light-responsive surface coating, hPG (hyperbranched polyglycerol)-SP, to control the adsorption of proteins and adhesion of cells. In the normal state, the SP groups on the coating surface were in hydrophobic ring-closed form, which promotes the nonspecific protein adsorption and cell adhesion.

High-Antifouling Polymer Brush Coatings on Nonpolar Surfaces via Adsorption-Cross-Linking Strategy.

A new "adsorption-cross-linking" technology is presented to generate a highly dense polymer brush coating on various nonpolar substrates, including the most inert and low-energy surfaces of poly(dimethylsiloxane) and poly(tetrafluoroethylene). This prospective surface modification strategy is based on a tailored bifunctional amphiphilic block copolymer with benzophenone units as the hydrophobic anchor/chemical cross-linker and terminal azide groups for in situ postmodification. The resulting polymer brushes exhibited long-term and ultralow protein adsorption and cell adhesion benefiting from the high density and high hydration ability of polyglycerol blocks.

Bioinspired Universal Monolayer Coatings by Combining Concepts from Blood Protein Adsorption and Mussel Adhesion.

Despite the increasing need for universal polymer coating strategies, only a few approaches have been successfully developed, and most of them are suffering from color, high thickness, or high roughness. In this paper, we present for the first time a universal monolayer coating that is only a few nanometers thick and independent of the composition, size, shape, and structure of the substrate. The coating is based on a bioinspired synthetic amphiphilic block copolymer that combines two concepts from blood protein adsorption and mussel adhesion.

Surface-Independent Hierarchical Coatings with Superamphiphobic Properties.

Facile approaches for the fabrication of substrate independent superamphiphobic surfaces that can repel both water and organic liquids have been limited. The design of such super-repellent surfaces is still a major challenge of surface chemistry and physics. Herein, we describe a simple and efficient dip-coating approach for the fabrication of highly hierarchical surface coatings with superamphiphobic properties for a broad range of materials based on a mussel-inspired dendritic polymer (MI-dPG).