scholarly journals Hydroxyl Groups Induce Bioactivity in Silica/Chitosan Aerogels Designed for Bone Tissue Engineering. In Vitro Model for the Assessment of Osteoblasts Behavior

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2802
Author(s):  
Antonio Perez-Moreno ◽  
María de las Virtudes Reyes-Peces ◽  
Deseada María de los Santos ◽  
Gonzalo Pinaglia-Tobaruela ◽  
Emilio de la Orden ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Crystal Nucleation ◽  
Elastic Behavior ◽  
Molar Ratio ◽  
Apatite Crystal ◽  
Hydroxyl Groups ◽  
Oh Groups ◽  
Composite Aerogels ◽  
Hybrid Aerogels

Silica (SiO2)/chitosan (CS) composite aerogels are bioactive when they are submerged in simulated body fluid (SBF), causing the formation of bone-like hydroxyapatite (HAp) layer. Silica-based hybrid aerogels improve the elastic behavior, and the combined CS modifies the network entanglement as a crosslinking biopolymer. Tetraethoxysilane (TEOS)/CS is used as network precursors by employing a sol-gel method assisted with high power ultrasound (600 W). Upon gelation and aging, gels are dried in supercritical CO2 to obtain monoliths. Thermograms provide information about the condensation of the remaining hydroxyl groups (400–700 °C). This step permits the evaluation of the hydroxyl group’s content of 2 to 5 OH nm−2. The formed Si-OH groups act as the inductor of apatite crystal nucleation in SBF. The N2 physisorption isotherms show a hysteresis loop of type H3, characteristic to good interconnected porosity, which facilitates both the bioactivity and the adhesion of osteoblasts cells. After two weeks of immersion in SBF, a layer of HAp microcrystals develops on the surface with a stoichiometric Ca/P molar ratio of 1.67 with spherulite morphology and uniform sizes of 6 μm. This fact asserts the bioactive behavior of these hybrid aerogels. Osteoblasts are cultured on the selected samples and immunolabeled for cytoskeletal and focal adhesion expression related to scaffold nanostructure and composition. The initial osteoconductive response observes points to a great potential of tissue engineering for the designed composite aerogels.

scholarly journals Structure-Antifungal Activity Relationships of Polyene Antibiotics of the Amphotericin B Group

2013 ◽  
Vol 57 (8) ◽  
pp. 3815-3822 ◽  
Author(s):  
Anna N. Tevyashova ◽  
Evgenia N. Olsufyeva ◽  
Svetlana E. Solovieva ◽  
Svetlana S. Printsevskaya ◽  
Marina I. Reznikova ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Amphotericin B ◽  
Cooh Group ◽  
Hydroxyl Groups ◽  
Activity Data ◽  
Oh Groups ◽  
Polyene Antibiotics ◽  
High Antifungal Activity

ABSTRACTA comprehensive comparative analysis of the structure-antifungal activity relationships for the series of biosynthetically engineered nystatin analogues and their novel semisynthetic derivatives, as well as amphotericin B (AMB) and its semisynthetic derivatives, was performed. The data obtained revealed the significant influence of the structure of the C-7 to C-10 polyol region on the antifungal activity of these polyene antibiotics. Comparison of positions of hydroxyl groups in the antibiotics andin vitroantifungal activity data showed that the most active are the compounds in which hydroxyl groups are in positions C-8 and C-9 or positions C-7 and C-10. Antibiotics with OH groups at both C-7 and C-9 had the lowest activity. The replacement of the C-16 carboxyl with methyl group did not significantly affect thein vitroantifungal activity of antibiotics without modifications at the amino group of mycosamine. In contrast, the activity of the N-modified derivatives was modulated both by the presence of CH3or COOH group in the position C-16 and by the structure of the modifying substituent. The most active compounds were testedin vivoto determine the maximum tolerated doses and antifungal activity on the model of candidosis sepsis in leukopenic mice (cyclophosphamide-induced). Study of our library of semisynthetic polyene antibiotics led to the discovery of compounds, namely,N-(l-lysyl)-BSG005 (compound 3n) and, especially,l-glutamate of 2-(N,N-dimethylamino)ethyl amide of S44HP (compound 2j), with high antifungal activity that were comparable inin vitroandin vivotests to AMB and that have better toxicological properties.

Synthesis of Biodegradable Polyester by Polycondensation with Tunable Properties

2015 ◽  
Vol 1119 ◽  
pp. 418-422
Author(s):  
Lee Xiau Yeen ◽  
Mat Uzir Wahit
Keyword(s):  
Drug Delivery ◽  
Tissue Engineering ◽  
Material Properties ◽  
Drug Delivery Systems ◽  
Molar Ratio ◽  
Cross Link ◽  
In Vitro Degradation ◽  
Broad Application ◽  
Dodecanedioic Acid

A biodegradable cross-linked polyester, poly (1, 8-octanediol-glycerol-dodecanedioate) (POGDA) was prepared from 1, 8-octanediol (Oct), glycerol (Gly) and dodecanedioic acid (DA) without any catalyst. One of the factors, molar ratio of monomers greatly affects the material properties of POGDA and the effect was evaluated. Result showed that the glycerol acts as cross-link agent. When the molar ratio of glycerol increased, the gel content of POGDA became higher. POGDA has a range of glass transition temperature (Tg) with different monomers’ molar ratio. Exist of melting point (Tm) indicated the crystallline region in the polymer. POGDA with low molar ratio of glycerol has high Tm due to the bigger region of crystal. In vitro degradation was performed to investigate the biodegradation behaviour of POGDA. The polymer with tunable material properties by tailoring monomers’ molar ratio is expected to have broad application in medical fields such as drug delivery systems and tissue engineering.

scholarly journals Efficacy of Bacterial Nanocellulose in Hard Tissue Regeneration: A Review

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4777
Author(s):  
Anuj Kumar ◽  
Sung-Soo Han
Keyword(s):  
Tissue Engineering ◽  
Tissue Regeneration ◽  
Cellular Response ◽  
Future Research ◽  
Hydroxyl Groups ◽  
Hard Tissue ◽  
Engineering Applications ◽  
Bacterial Nanocellulose

Bacterial nanocellulose (BNC, as exopolysaccharide) synthesized by some specific bacteria strains is a fascinating biopolymer composed of the three-dimensional pure cellulosic nanofibrous matrix without containing lignin, hemicellulose, pectin, and other impurities as in plant-based cellulose. Due to its excellent biocompatibility (in vitro and in vivo), high water-holding capacity, flexibility, high mechanical properties, and a large number of hydroxyl groups that are most similar characteristics of native tissues, BNC has shown great potential in tissue engineering applications. This review focuses on and discusses the efficacy of BNC- or BNC-based biomaterials for hard tissue regeneration. In this review, we provide brief information on the key aspects of synthesis and properties of BNC, including solubility, biodegradability, thermal stability, antimicrobial ability, toxicity, and cellular response. Further, modification approaches are discussed briefly to improve the properties of BNC or BNC-based structures. In addition, various biomaterials by using BNC (as sacrificial template or matrix) or BNC in conjugation with polymers and/or fillers are reviewed and discussed for dental and bone tissue engineering applications. Moreover, the conclusion with perspective for future research directions of using BNC for hard tissue regeneration is briefly discussed.

scholarly journals Formulation and In-Vitro Characterization of Chitosan-Nanoparticles Loaded with the Iron Chelator Deferoxamine Mesylate (DFO)

Pharmaceutics ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 238 ◽  
Author(s):  
Maria Lazaridou ◽  
Evi Christodoulou ◽  
Maria Nerantzaki ◽  
Margaritis Kostoglou ◽  
Dimitra Lambropoulou ◽  
...  
Keyword(s):  
Sodium Tripolyphosphate ◽  
Drug Loading ◽  
Chitosan Nanoparticles ◽  
Entrapment Efficiency ◽  
Molar Ratio ◽  
Release Mechanism ◽  
Hydroxyl Groups ◽  
Deferoxamine Mesylate ◽  
Pharmacologically Active

The objective of this study was to develop chitosan (CS) nanoparticles (NPs) loaded with deferoxamine mesylate (DFO) for slow release of this iron-chelating drug. Drug nanoencapsulation was performed via ionic gelation of chitosan using sodium tripolyphosphate (TPP) as cross-linker. Nanoparticles with a size ranging between 150 and 400 nm were prepared for neat CS/TPP with a 2/1 molar ratio while their yield was directly dependent on the applied stirring rate during the preparation process. DFO at different content (20, 45 and 75 wt %) was encapsulated into these nanoparticles. We found that drug loading correlates with increasing DFO content while the entrapment efficiency has an opposite behavior due to the high solubility of DFO. Hydrogen-bonding between amino and hydroxyl groups of DFO with reactive groups of CS were detected using FT-IR spectroscopy while X-ray diffraction revealed that DFO was entrapped in amorphous form in the CS nanoparticles. DFO release is directly dependent on the content of loaded drug, while model analysis revealed that the release mechanism of DFO for the CS/TPP nanoparticles is by diffusion. Treatment of murine RAW 264.7 macrophages with nanoencapsulated DFO promoted an increased expression of transferrin receptor 1 (TfR1) mRNA, a typical homeostatic response to iron deficiency. These data provide preliminary evidence for release of pharmacologically active DFO from the chitosan nanoparticles.

scholarly journals Chitosan-GPTMS-Silica Hybrid Mesoporous Aerogels for Bone Tissue Engineering

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2723
Author(s):  
María V. Reyes-Peces ◽  
A. Pérez-Moreno ◽  
Deseada María de-los-Santos ◽  
María del Mar Mesa-Díaz ◽  
Gonzalo Pinaglia-Tobaruela ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Sol Gel ◽  
Polymer Networks ◽  
Supercritical Drying ◽  
Hybrid Structure ◽  
Stress Fibers ◽  
Molar Ratio ◽  
Surface Areas ◽  
Silica Hybrid

This study introduces a new synthesis route for obtaining homogeneous chitosan (CS)-silica hybrid aerogels with CS contents up to 10 wt%, using 3-glycidoxypropyl trimethoxysilane (GPTMS) as coupling agent, for tissue engineering applications. Aerogels were obtained using the sol-gel process followed by CO2 supercritical drying, resulting in samples with bulk densities ranging from 0.17 g/cm3 to 0.38 g/cm3. The textural analysis by N2-physisorption revealed an interconnected mesopore network with decreasing specific surface areas (1230–700 m2/g) and pore sizes (11.1–8.7 nm) by increasing GPTMS content (2–4 molar ratio GPTMS:CS monomer). In addition, samples exhibited extremely fast swelling by spontaneous capillary imbibition in PBS solution, presenting swelling capacities from 1.75 to 3.75. The formation of a covalent crosslinked hybrid structure was suggested by FTIR and confirmed by an increase of four hundred fold or more in the compressive strength up to 96 MPa. Instead, samples synthesized without GPTMS fractured at only 0.10–0.26 MPa, revealing a week structure consisted in interpenetrated polymer networks. The aerogels presented bioactivity in simulated body fluid (SBF), as confirmed by the in vitro formation of hydroxyapatite (HAp) layer with crystal size of approximately 2 µm size in diameter. In vitro studies revealed also non cytotoxic effect on HOB® osteoblasts and also a mechanosensitive response. Additionally, control cells grown on glass developed scarce or no stress fibers, while cells grown on hybrid samples showed a significant (p < 0.05) increase in well-developed stress fibers and mature focal adhesion complexes.

In Vitro Anticoagulant Activity of Esters of Heparin.

1979 ◽  
Author(s):  
J. Mardiguian ◽  
M. Trillou ◽  
J. Marin
Keyword(s):  
Molecular Weight ◽  
Ion Exchange ◽  
Chemical Modification ◽  
Anticoagulant Activity ◽  
Gel Filtration ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Hydroxyl Groups ◽  
Oh Groups

Chemical modification of Heparin by esterification of its hydroxyl groups has been carried out in order to study its influence on the in vitro anticoagulant activity. Beef and pig mucosal Heparins have been fractionated by gel filtration and by ion-exchange chromatography to yield fractions which have been esterified.Two types of esters have been prepared : 4-chlorophenoxy-acetic and 4-chlorophenoxy-isobutyric.The anticoagulant activity of the these esters has been evaluated in vitro (using U.S.P. method, anti-Xa and anti-thrombin assays) and correlated with their chlorine content and U.V. absorption.This study shows that the in vitro anticoagulant activity of heparin is decreased by esterification of its OH groups, to an extent depending upon the type of ester, the molecular weight and the degree of substitution.The results of these experiments will be reported and discussed in detail.

Manganese (II), ferric (III), cobalt (II) and copper (II) thiosemicarbazone Schiff base complexes: Synthesis, spectroscopic, molecular docking and biological discussions

2020 ◽  
Vol 10 (2) ◽  
pp. 290-300
Author(s):  
Asma S. Al-Wasidi ◽  
Ahmed M. Naglah ◽  
Mohamed A. Al-Omar ◽  
Abdul-Rahman M. Al-Obaid ◽  
Eid H. Alosaimi ◽  
...  
Keyword(s):  
Schiff Base ◽  
Metal Ions ◽  
Electronic Absorption Spectra ◽  
Schiff Base Complexes ◽  
Molar Ratio ◽  
Central Metal ◽  
Tetrahedral Geometry ◽  
Keto Form ◽  
Oh Groups

Mn(II), Fe(III), Co(II) and Cu(II) Schiff base complexes with general formula ML−2 .nH2O (where M is a respected metal ions and L−2 is the Schiff base). The Schiff base (L = TSCPA) was formed by the condensation of thiosemicarbazide and phthalic anhydride in acetic acid. The microanalytical analysis confirmed the 1:1 (metal: ligand) molar ratio. Magnetic susceptibility and electronic absorption spectra were suggested that the Fe(III) and Co(II) complexes were octahedral structure but the Mn(II) and Cu(II) complexes were tetrahedral geometry. FTIR spectra reveal that the ligand exists, predominantly, as keto form in a solid state but as enol form in the alkaline medium. The coordination between TSCPA chelate and central metal ions take place through nitrogen –NH, sulphur C=S and oxygen –OH groups. Based on the molar conductance measurements the complexes may be formulated as [Mn(L)(H2O)] · 4H2O, [Fe(L)(Cl)(H2O)2] · 2H2O, [Co(L)(H2O)3] · 3H2O and [Cu(L)(H2O)] · 4H2O due to their non-electrolytic behavior. The Schiff base ligand and their metal complexes were screened in vitro against G(+Ve) and G(−Ve) bacteria. This study came after proactive step, which concerning with docking study against pathogen proteins corresponding to microorganisms for bacteria and fungi, which will be scanned in vitro study. Thermogravimetry (TGA) and differential thermogravimetry (DTG) were discussed.

Poly(glycerol sebacate)—A Novel Biodegradable Elastomer for Tissue Engineering

2002 ◽  
Vol 724 ◽  
Author(s):  
Yadong Wang ◽  
Barbara J. Sheppard ◽  
Robert Langer
Keyword(s):  
Tissue Engineering ◽  
Three Dimensional ◽  
Hydroxyl Groups ◽  
Random Coils ◽  
Dimensional Network ◽  
Implantation Sites ◽  
Good Biocompatibility ◽  
Normal Architecture

AbstractBiodegradable polymers have significant potential in biotechnology and bioengineering. However, for some applications, they are limited by their inferior mechanical properties and unsatisfactory compatibility with cells and tissues. A strong, biodegradable, and biocompatible elastomer could be useful for fields such as tissue engineering, drug delivery, and in vivo sensing [1, 2]. We designed, synthesized, and characterized a tough biodegradable elastomer from biocompatible monomers. This elastomer forms a covalently crosslinked three-dimensional network of random coils with hydroxyl groups attached to its backbone. Both crosslinking and the hydrogen bonding interactions between the hydroxyl groups likely contributes to the unique properties of the elastomer. In vitro and in vivo studies show the polymer has good biocompatibility. Subcutaneous (SC) polymer implants are absorbed completely within 60 days with restoration of the implantation sites to their normal architecture.

Decellularized bone extracellular matrix in skeletal tissue engineering

2020 ◽  
Vol 48 (3) ◽  
pp. 755-764
Author(s):  
Benjamin B. Rothrauff ◽  
Rocky S. Tuan
Keyword(s):  
Tissue Engineering ◽  
Bone Regeneration ◽  
Tissue Regeneration ◽  
Animal Studies ◽  
Tumor Resection ◽  
Regenerative Capacity ◽  
Skeletal Tissue ◽  
Large Bone

Bone possesses an intrinsic regenerative capacity, which can be compromised by aging, disease, trauma, and iatrogenesis (e.g. tumor resection, pharmacological). At present, autografts and allografts are the principal biological treatments available to replace large bone segments, but both entail several limitations that reduce wider use and consistent success. The use of decellularized extracellular matrices (ECM), often derived from xenogeneic sources, has been shown to favorably influence the immune response to injury and promote site-appropriate tissue regeneration. Decellularized bone ECM (dbECM), utilized in several forms — whole organ, particles, hydrogels — has shown promise in both in vitro and in vivo animal studies to promote osteogenic differentiation of stem/progenitor cells and enhance bone regeneration. However, dbECM has yet to be investigated in clinical studies, which are needed to determine the relative efficacy of this emerging biomaterial as compared with established treatments. This mini-review highlights the recent exploration of dbECM as a biomaterial for skeletal tissue engineering and considers modifications on its future use to more consistently promote bone regeneration.

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