Conductive Peptide-Based MXene Hydrogel as a Piezoresistive Sensor.

Wearable pressure sensors have become increasingly popular for personal healthcare and motion detection applications due to recent advances in materials science and functional nanomaterials. In this study, a novel composite hydrogel is presented as a sensitive piezoresistive sensor that can be utilized for various biomedical applications, such as wearable skin patches and integrated artificial skin that can measure pulse and blood pressure, as well as monitor sound as a self-powered microphone. The hydrogel is composed of self-assembled short peptides containing aromatic, positively- or negatively charged amino acids combined with 2D TiCT MXene nanosheets.

Immunomodulatory fibrous hyaluronic acid-Fmoc-diphenylalanine-based hydrogel induces bone regeneration.

Aim: To investigate the potential of an ultrashort aromatic peptide hydrogelator integrated with hyaluronic acid (HA) to serve as a scaffold for bone regeneration.

Materials And Methods: Fluorenylmethyloxycarbonyl-diphenylalanine (FmocFF)/HA hydrogel was prepared and characterized using microscopy and rheology. Osteogenic differentiation of MC3T3-E1 preosteoblasts was investigated using Alizarin red, alkaline phosphatase and calcium deposition assays.

Stabilizing gelatin-based bioinks under physiological conditions by incorporation of ethylene-glycol-conjugated Fmoc-FF peptides.

Over the last decade, three-dimensional (3D) printing technologies have attracted the interest of researchers due to the possibility of fabricating tissue- and organ-like structures with similarities to the organ of interest. One of the most widely used materials for the fabrication of bioinks is gelatin (Gel) due to its excellent biocompatibility properties. However, in order to fabricate stable scaffolds under physiological conditions, the most common approach is to use gelatin methacrylate (GelMA) that allows the crosslinking and therefore the stabilization of the hydrogel through UV crosslinking.

Molecular Co-Assembly of Two Building Blocks Harnesses Both their Attributes into a Functional Supramolecular Hydrogel.

Engineering ordered nanostructures through molecular self-assembly of simple building blocks constitutes the essence of modern nanotechnology to develop functional supramolecular biomaterials. However, the lack of adequate chemical and functional diversity often hinders the utilization of unimolecular self-assemblies for practical applications. Co-assembly of two different building blocks can essentially harness both of their attributes and produce nanostructured macro-scale objects with improved physical properties and desired functional complexity.

Modification of a Single Atom Affects the Physical Properties of Double Fluorinated Fmoc-Phe Derivatives.

Supramolecular hydrogels formed by the self-assembly of amino-acid based gelators are receiving increasing attention from the fields of biomedicine and material science. Self-assembled systems exhibit well-ordered functional architectures and unique physicochemical properties. However, the control over the kinetics and mechanical properties of the end-products remains puzzling.

Improving the Mechanical Rigidity of Hyaluronic Acid by Integration of a Supramolecular Peptide Matrix.

Hyaluronic acid (HA), a major component of the extracellular matrix, is an attractive material for various medical applications. Yet, its low mechanical rigidity and fast in vivo degradation hinder its utilization. Here, we demonstrate the reinforcement of HA by its integration with a low-molecular-weight peptide hydrogelator to produce a composite hydrogel.

Motility flow and growth-cone navigation analysis during in vitro neuronal development by long-term bright-field imaging.

A long-term live-imaging workstation to follow the development of cultured neurons during the first few days in vitro (DIV) is developed. In order to monitor neuronal polarization and axonal growth by live imaging, we built a micro-incubator system that provides stable temperature, pH, and osmolarity in the culture dish under the microscope, while preserving environment sterility. We are able to image living neurons at 2 DIVs for 48 h with a temporal resolution of one frame for every 2 min.

Experimental results of revised Misell algorithm for imaging through weakly scattering biological tissue.

A Static random perturbation weakly scattering media may significantly reduce image quality, in many kinds of applications. An example of such a medium can be a soft tissue such as skin or flesh, through which one may wish to image an object, such as a bone, located behind. In this paper we present experimental results of newly developed deblurring approach for obtaining a better image of objects positioned behind static random perturbation media.

β-D-xylosides stimulate GAG synthesis in chondrocyte cultures due to elevation of the extracellular GAG domains, accompanied by the depletion of the intra-pericellular GAG pools, with alterations in the GAG profiles.

The familial disease of hereditary multiple exostoses is characterized by abnormal skeletal deformities requiring extensive surgical procedures. In hereditary multiple exostoses patients there is a shortage in the pericellular glycosaminoglycan (GAG) of heparan sulfate (HS), related to defective activity of HS glycosyltransferases, mainly in the pericellular regions of chondrocytes. This study searched for a novel approach employing xylosides with different aglycone groups priming a variety of GAG chains, in attempting to alter the GAG compositional profile.

Crystalline calcium carbonate and hydrogels as microenvironment for stem cells.

Stem cell development and fate decisions are dictated by the microenvironment in which the stem cell is embedded. Among the advanced goals of tissue engineering is the creation of a microenvironment that will support the maintenance and differentiation of the stem cell--based on embryonic and adult stem cells as potent, cellular sources--for a variety of clinical applications. This review discusses some of the approaches used to create regulatory and instructive microenvironments for the directed differentiation of mesenchymal stem cells (MSCs) using three-dimensional crystalline calcium carbonate biomaterials of marine origin combined with a hydrated gel based on hyaluronan.

Hyaluronan and mesenchymal stem cells: from germ layer to cartilage and bone.

A simple, linear polysaccharide with unique molecular functions, hyaluronan is a glycosaminoglycan whose biomechanical and hydrodynamic properties have been thoroughly characterized. However, the exact role the molecular mechanisms and signaling pathways of hyaluronan play in the regulation of stem cell fate, such as self-renewal and differentiation, remains to be determined. The abundance of hyaluronan in embryonic tissues indicates that it is highly important in developmental processes.

Structured drug-eluting bioresorbable films: microstructure and release profile.

Bioresorbable drug-eluting films can be used in many biomedical applications. Examples for such applications include biodegradable medical support devices which combine mechanical support with drug release and antibiotic-eluting film coatings for prevention of bacterial infections associated with orthopedic implants or during gingival healing. In the current study, bioresorbable drug-loaded polymer films are prepared by solution processing.

Gentamicin-loaded bioresorbable films for prevention of bacterial infections associated with orthopedic implants.

Adhesion of bacteria to biomaterials and the ability of many microorganisms to form biofilms on foreign bodies are well-established as major contributors to the pathogenesis of implant-associated infections. Treatment of bone infection remains problematic, due to the difficulty of systemically administered antibiotics to locally penetrate bone. The current research addresses this issue by focusing on the development and study of novel gentamicin-loaded bioresorbable films designed to serve as "coatings" for fracture fixation devices and prevent implant-associated infections.

Conversion of adipogenic to osteogenic phenotype using crystalline porous biomatrices of marine origin.

Adipogenic and osteogenic cells share part of the early differentiation cascade of mesenchymal stem cells (MSCs). The choice of a mesenchymal precursor cell to differentiate into a particular cell type is dictated by many spatial and temporal cues, including growth factors, neighboring mature cells, and the extracellular matrix (ECM), which plays an important role in bone formation. Whether adipocytes that have initiated differentiation along one lineage can convert into osteogenic lineage by merely interacting with materials having specific surface parameters is unknown.

Promoter protection by a transcription factor acting as a local topological homeostat.

Binding of the Escherichia coli global transcription factor FIS to the upstream activating sequence (UAS) of stable RNA promoters activates transcription on the outgrowth of cells from stationary phase. Paradoxically, while these promoters require negative supercoiling of DNA for optimal activity, FIS counteracts the increase of negative superhelical density by DNA gyrase. We demonstrate that binding of FIS at the UAS protects the rrnA P1 promoter from inactivation at suboptimal superhelical densities.

Analysis of the shut-off of ribosomal RNA promoters in Escherichia coli upon entering the stationary phase of growth.

Most bacterial RNA consists of stable RNA which is composed of rRNA and tRNA. We have followed by primer extension analysis the level of ribosomal RNA synthesis along the growth phases of a cell culture. A sharp drop in rRNA synthesis was observed upon the transition from the exponential to the stationary phase of growth.

Expression of the genes coding for the Escherichia coli integration host factor are controlled by growth phase, rpoS, ppGpp and by autoregulation.

Transcriptional control of the himA and the himD/hip genes coding for the two subunits of the integration host factor (IHF) was investigated. The promoters for the two genes were identified by the use of primer extension and S1 analysis. Expression from both promoters was found to increase as the cells enter stationary phase.