Hayshoneycutt5374

Reinforcing mechanically weak hydrogels with fibers is a promising route to obtain strong and tough materials for biomedical applications while retaining a favorable cell environment. The resulting hierarchical structure recreates structural elements of natural tissues such as articular cartilage, with fiber diameters ranging from the nano- to microscale. Through control of properties such as the fiber diameter, orientation, and porosity, it is possible to design materials which display the nonlinear, synergistic mechanical behavior observed in natural tissues. In order to fully exploit these advantages, it is necessary to understand the structure-property relationships in fiber-reinforced hydrogels. However, there are currently limited models which capture their complex mechanical properties. The majority of reported fiber-reinforced hydrogels contain fibers obtained by electrospinning, which allows for limited spatial control over the fiber scaffold and limits the scope for systematic mechanical testing studies. Nevertheless, new manufacturing techniques such as melt electrowriting and bioprinting have emerged, which allow for increased control over fiber deposition and the potential for future investigations on the effect of specific structural features on mechanical properties. In this review, we therefore explore the mechanics of fiber-reinforced hydrogels, and the evolution of their design and manufacture from replicating specific features of biological tissues to more complex structures, by taking advantage of design principles from both tough hydrogels and fiber-reinforced composites. By highlighting the overlap between these fields, it is possible to identify the remaining challenges and opportunities for the development of effective biomedical devices.The long-range biomechanical force propagating across a large scale may reserve the capability to trigger coordinative responses within cell population such as during angiogenesis, epithelial tubulogenesis, and cancer metastasis. How cells communicate in a distant manner within the group for self-assembly remains largely unknown. Here, we found that airway smooth muscle cells (ASMCs) rapidly self-assembled into a well-constructed network on 3D Matrigel containing type I collagen (COL), which relied on long-range biomechanical force across the matrix to direct cell-cell distant interactions. Similar results happened by HUVEC cells to mimic angiogenesis. Interestingly, single ASMCs initiated multiple extended protrusions precisely pointing to neighboring cells in distance (100-300 μm away or 5-10 folds of the diameter of a round single cell), depending on traction force sensing. Individual ASMCs mechanosensed each other to move directionally on both nonfibrous Matrigel only and Matrigel containing fibrous COL but lost mutual sensing on the cross-linked gel or coated glass due to no long-range force transmission. The bead tracking assay demonstrated distant transmission of traction force (up to 400 μm) during the matrix deformation, and finite element method modeling confirmed the consistency between maximum strain distribution on the matrix and cell directional movements in experiments. selleck inhibitor Furthermore, ASMCs recruited COL from the hydrogel to build a fibrous network to mechanically stabilize the cell network. Our results revealed principally that cells can sense traction force transmitted through the matrix to initiate cell-cell distant mechanical communications, resulting in cell directional migration and coordinated cell and COL self-assembly with active matrix remodeling. As an interesting phenomenon, cells seem to be able to "make a phone call" via long-range biomechanics, which implicates physiological importance such as for tissue pattern formation.The emergence of antibiotic resistance and the increasing rate of bacterial infections have motivated scientists to explore novel antibacterial materials and strategies to circumvent this challenge. Gels fabricated from ultrashort self-assembled peptides have turned out to be the most promising bactericidal materials. Self-assembled Fmoc-Phe-Phe gels have been extensively investigated earlier, and it has been shown that these gels possess potent bactericidal properties but suffer from disadvantages, such as poor proteolytic stabilities. In the present work, we report the highly potent bactericidal activities and proteolytic stability of gels fabricated from Fmoc-l-Arg-d-Phe-d-Phe-CONH2 (RFF) peptide, which are best in class. We fabricated and characterized self-assembled gels (1-2% w/v) from Fmoc-d-Phe-d-Phe-CONH2 (FF), Fmoc-l-His-d-Phe-d-Phe-CONH2 (HFF), and Fmoc-l-Arg-d-Phe-d-Phe-CONH2 (RFF) in aq dimethyl sulfoxide (35% v/v). The gels were characterized for their surface morphology, viscoelastic, self-healing, and stability characteristics. On incubation with proteolytic enzymes, FF gels did not show statistically significant degradation, and HFF and RFF gels showed only 43 and 32% degradation within 72 h at 37 °C, which is much better than gels reported earlier. The RFF gels (2%) exhibited more than 90% inhibition against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) within 6 h, and the activities were sustained for up to 72 h. The high-resolution transmission electron microscopy studies indicated electrostatic interactions between the gel and bacterial membrane components, leading to cell lysis and death, which was further confirmed by the bacterial cell Live/Dead assay. MTT assay showed that the gels were not toxic to mammalian cells (L929). The bactericidal characteristics of RFF gels have not been reported so far. The RFF gels show strong potential for treating device-related infections caused by antimicrobial-resistant bacteria.Delivery of therapeutics to the intestinal region bypassing the harsh acidic environment of the stomach has long been a research focus. On the other hand, monitoring a system's pH during drug delivery is a crucial diagnosis factor as the activity and release rate of many therapeutics depend on it. This study answered both of these issues by fabricating a novel nanocomposite hydrogel for intestinal drug delivery and near-neutral pH sensing at the same time. Gelatin nanocomposites (GNCs) with varying concentrations of carbon dots (CDs) were fabricated through simple solvent casting methods. Here, CDs served a dual role and simultaneously acted as a cross-linker and chromophore, which reduced the usage of toxic cross-linkers. The proposed GNC hydrogel sample acted as an excellent pH sensor in the near-neutral pH range and could be useful for quantitative pH measurement. A model antibacterial drug (cefadroxil) was used for the in vitro drug release study at gastric pH (1.2) and intestinal pH (7.4) conditions. A moderate and sustained drug release profile was noticed at pH 7.