Search results for "Biomaterial"

Correlation between micro-hardness and mineral content in healthy human enamel

2016

Background Enamel is the hardest and the stiffest tissue in the human body. The enamel undergoes multidirectional stresses, withstands multimillion chewing cycles, all while protecting the internal dentin and pulp from damage due to mechanical overload and exposure to the harsh chemical environment of the mouth. Raman spectroscopy allows to study enamel mineral content in a non-destructive and site-specific way. While Raman spectroscopy has been applied in other studies to assess tooth mineralization, there are no studies that examine the relationship between micro-hardness and mineral content of the untreated enamel. An understanding of this relationship is extremely important in a clinica…

Structural commonalities and deviations in the hierarchical organization of crossed-lamellar shells: A case study on the shell of the bivalve Glycyme…

2016

11 pages; International audience; The structural organization of the palliostracum—the dominant part of the shell which is formed by the mantle cells—of Glycymeris glycymeris (Linné 1758) is comprised of five hierarchical levels with pronounced structural commonalities and deviations from other crossed-lamellar shells. The hierarchical level known as second order lamellae, present within other crossed-lamellar shells, is absent highlighting a short-coming of the currently used nomenclature. On the mesoscale, secondary microtubules penetrate the palliostracum and serve as crack arrestors. Moreover, the growth lamellae follow bent trajectories possibly impacting crack propagation, crack defle…

Effect of in situ aspartame mouthwash to prevent intrinsic and extrinsic erosive tooth wear

2020

Background The aim was to evaluate whether aspartame regular mouthwash prior to erosive challenges with citric or hydrochloric acids would be able to prevent erosive enamel wear. Material and methods This randomized, single blind in situ study was conducted with 3 crossover phases of 5 days. Polished bovine enamel blocks (n=252) were randomly divided among 6 groups/ 3 phases/ 21 volunteers. The groups under study were: aspartame solution (0.024% of aspartame in deionized water - experimental group), deionized water (negative-control) and stannous-containing solution (Elmex® Erosion Protection Dental Rinse; positive-control); subjected to erosion on citric acid or hydrochloric acid. Four tim…

In Situ, Light-Guided Axon Growth on Biomaterials via Photoactivatable Laminin Peptidomimetic IK(HANBP)VAV

2018

The ability to guide the growth of neurites is relevant for reconstructing neural networks and for nerve tissue regeneration. Here, a biofunctional hydrogel that allows light-based directional control of axon growth in situ is presented. The gel is covalently modified with a photoactivatable derivative of the short laminin peptidomimetic IKVAV. This adhesive peptide contains the photoremovable group 2-(4′-amino-4-nitro-[1,1′-biphenyl]-3-yl)propan-1-ol (HANBP) on the Lys rest that inhibits its activity. The modified peptide is highly soluble in water and can be simply conjugated to -COOH containing hydrogels via its terminal -NH 2 group. Light exposure allows presentation of the IKVAV adhesi…

Imaging Bacterial Colonies and Phage-Bacterium Interaction at Sub-Nanometer Resolution Using Helium-Ion Microscopy

2017

Imaging of microbial interactions has so far been based on well‐established electron microscopy methods. This study presents a new way to study bacterial colonies and interactions between bacteria and their viruses, bacteriophages (phages), in situ on agar plates using helium ion microscopy (HIM). In biological imaging, HIM has advantages over traditional scanning electron microscopy with its sub‐nanometer resolution, increased surface sensitivity, and the possibility to image nonconductive samples. Furthermore, by controlling the He beam dose or by using heavier Ne ions, the HIM instrument provides the possibility to mill out material in the samples, allowing for subsurface imaging and in …

2021

In addition to their chemical composition various physical properties of synthetic bone substitute materials have been shown to influence their regenerative potential and to influence the expression of cytokines produced by monocytes, the key cell-type responsible for tissue reaction to biomaterials in vivo. In the present study both the regenerative potential and the inflammatory response to five bone substitute materials all based on β-tricalcium phosphate (β-TCP), but which differed in their physical characteristics (i.e., granule size, granule shape and porosity) were analyzed for their effects on monocyte cytokine expression. To determine the effects of the physical characteristics of …

Simultaneous Boron Ion‐Channel/Growth Factor Receptor Activation for Enhanced Vascularization

2018

[EN] Boron ion is essential in metabolism and its concentration is regulated by ion-channel NaBC1. NaBC1 mutations cause corneal dystrophies such as Harboyan syndrome. Here we propose a 3D molecular model for NaBC1 and show that simultaneous stimulation of NaBC1 and vascular growth factor receptors (VEGFR) promote angiogenesis in vitro and in vivo with ultra-low concentrations of VEGF. We show Human Umbilical Vein Endothelial Cells (HUVEC) organization into tubular structures indicative of vascularization potential. Enhanced cell sprouting was found only in the presence of VEGF and boron, effect abrogated after blocking NaBC1. We demonstrate that stimulated NaBC1 promotes angiogenesis via P…

Electrospun poly(hydroxybutyrate) scaffolds promote engraftment of human skin equivalents via macrophage M2 polarization and angiogenesis.

2018

Human dermo-epidermal skin equivalents (DE) comprising in vitro expanded autologous keratinocytes and fibroblasts are a good option for massive burn treatment. However, the lengthy expansion time required to obtain sufficient surface to cover an extensive burn together with the challenging surgical procedure limits their clinical use. The integration of DE and biodegradable scaffolds has been proposed in an effort to enhance their mechanical properties. Here, it is shown that poly(hydroxybutyrate) electrospun scaffolds (PHB) present good biocompatibility both in vitro and in vivo and are superior to poly-epsilon-caprolactone electrospun scaffolds as a substrate for skin reconstruction. Impl…

Liver-Kidney-on-Chip To Study Toxicity of Drug Metabolites

2017

Advances in organ-on-chip technologies for the application in in vitro drug development provide an attractive alternative approach to replace ethically controversial animal testing and to establish a basis for accelerated drug development. In recent years, various chip-based tissue culture systems have been developed, which are mostly optimized for cultivation of one single cell type or organoid structure and lack the representation of multi organ interactions. Here we present an optimized microfluidic chip design consisting of interconnected compartments, which provides the possibility to mimic the exchange between different organ specific cell types and enables to study interdependent cel…

TLR4 stimulation by LPS enhances angiogenesis in a co-culture system consisting of primary human osteoblasts and outgrowth endothelial cells

2015

The development of new approaches leading to fast and successful vascularization of tissue-engineered constructs is one of the most intensively studied subjects in tissue engineering and regenerative medicine. Recently, TLR4 activation and LPS stimulation of endothelial cells have been reported to promote angiogenesis in a variety of settings. In this study, we demonstrate that TLR4 activation by Ultrapure LPS Escherichia coli 0111:B4 (LPS-EB) significantly enhances microvessel formation in a co-culture system consisting of outgrowth endothelial cells (OECs) and primary human osteoblasts (pOBs). The precise modes of TLR4 action on the process of angiogenesis have also been investigated in t…