Alginate/human elastin-like polypeptide composite films with antioxidant properties for potential wound healing application

In this contribution we describe the preparation and characterization of a series of cross-linked films based on the combination of an elastin-derived biomimetic polypeptide (Human elastin-like polypeptide (HELP)) with alginate (ALG) to obtain a composite with enhanced properties. ALG/HELP composite films loaded with the hydrophobic natural antioxidant curcumin were prepared by solvent casting method followed by the cross-linking with calcium chloride. The compatibility between the two components as well as the final properties was evaluated. The micro-morphological study of films showed a homogeneous structure, but the film tensile strength decrease with HELP content and elongation at break was adversely affected by biopolymer addition. Spectroscopic and thermal analyses confirmed an interaction between ALG and HELP which also causes a modification in swelling kinetics and faster degradation. Moreover, the study of curcumin release showed a controlled delivery up to 10\u202fdays with a faster release rate in the presence of HELP. Human Dermal Fibroblasts (hDF) were used to test the in vitro cytocompatibility. The antioxidant activity correlated to the increase of HELP content suggested the applicability of these composites to develop smart biomaterials. Overall, these features indicated how this composite material has considerable potential as customizable platforms for various biomedical applications

Functionalized PCL/HA nanocomposites as microporous membranes for bone regeneration

In the present work, microporous membranes based on poly(ε-caprolactone) (PCL) and PCL functionalized with amine (PCL-DMAEA) or anhydride groups (PCL-MAGMA) were realized by solvent-non solvent phase inversion and proposed for use in Guided Tissue Regeneration (GTR). Nanowhiskers of hydroxyapatite (HA) were also incorporated in the polymer matrix to realize nanocomposite membranes. Scanning Electron Microscopy (SEM) showed improved interfacial adhesion with HA for functionalized polymers, and highlighted substantial differences in the porosity. A relationship between the developed porous structure of the membrane and the chemical nature of grafted groups was proposed. Compared to virgin PCL, hydrophilicity increases for functionalized PCL, while the addition of HA influences significantly the hydrophilic characteristics only in the case of virgin polymer. A significant increase of in vitro degradation rate was found for PCL-MAGMA based membranes, and at lower extent of PCL-DMAEA membranes. The novel materials were investigated regarding their potential as support for cell growth in bone repair using multipotent mesenchymal stromal cells (MSC) as a model. MSC plated onto the various membranes were analyzed in terms of adhesion, proliferation and osteogenic capacity that resulted to be related to chemical as well as porous structure. In particular, PCL-DMAEA and the relative nanocomposite membranes are the most promising in terms of cell-biomaterial interactions

Alginate Hydrogels Coated with Chitosan for Wound Dressing

In this work, a coating of chitosan onto alginate hydrogels was realized using the water-soluble hydrochloride form of chitosan (CH-Cl), with the dual purpose of imparting antibacterial activity and delaying the release of hydrophilic molecules from the alginate matrix. Alginate hydrogels with different calcium contents were prepared by the internal setting method and coated by immersion in a CH-Cl solution. Structural analysis by cryo-scanning electron microscopy was carried out to highlight morphological alterations due to the coating layer. Tests in vitro with human mesenchymal stromal cells (MSC) were assessed to check the absence of toxicity of CH-Cl. Swelling, stability in physiological solution and release characteristics using rhodamine B as the hydrophilic model drug were compared to those of relative uncoated hydrogels. Finally, antibacterial activity against Escherichia coli was tested. Results show that alginate hydrogels coated with chitosan hydrochloride described here can be proposed as a novel medicated dressing by associating intrinsic antimicrobial activity with improved sustained release characteristics

Functionalized PCL/HA nanocomposites as microporous membranes for bone regeneration

International audienceIn the present work, microporous membranes based on poly(ε-caprolactone) (PCL) and PCL functionalized withamine (PCL-DMAEA) or anhydride groups (PCL-MAGMA) were realized by solvent–non solvent phase inversionand proposed for use in Guided Tissue Regeneration (GTR). Nanowhiskers of hydroxyapatite (HA) were also incorporatedin the polymer matrix to realize nanocomposite membranes. Scanning Electron Microscopy (SEM)showed improved interfacial adhesion with HA for functionalized polymers, and highlighted substantial differencesin the porosity. A relationship between the developed porous structure of the membrane and the chemicalnature of grafted groups was proposed. Compared to virgin PCL, hydrophilicity increases for functionalized PCL,while the addition of HA influences significantly the hydrophilic characteristics only in the case of virgin polymer.A significant increase of in vitro degradation rate was found for PCL-MAGMA based membranes, and at lowerextent of PCL-DMAEA membranes. The novel materials were investigated regarding their potential as supportfor cell growth in bone repair using multipotent mesenchymal stromal cells (MSC) as a model. MSC platedonto the various membranes were analyzed in terms of adhesion, proliferation and osteogenic capacity that resultedto be related to chemical as well as porous structure. In particular, PCL-DMAEA and the relative nanocompositemembranes are the most promising in terms of cell-biomaterial interactions

Shape Memory behavior of Functionalised Poly(e-caprolactone) Crosslinked by Hexamethylene-Diisocyanate

In this study, the shape memory behaviour of poly(ε-caprolactone) (PCL) with different crosslinking degrees was investigated. PCL was first functionalised with maleic anhydride (MA) and glycidyl methacrylate (GMA), and successively chemically crosslinked by hexamethylene diisocianate (HMDI). The crosslinking reaction was studied through with a rotational stress rheometer, while the shape memory behaviour was analyzed with cyclic thermomechanical experiments and optical microscopy. The results show that the new materials exhibit good shape memory behaviour and good stability of the shape recovery under consecutive cycles in the range 55 - 70°C, can reach high level of stretching, and are furthermore characterised by high recovery speed. These results are promising for potential practical applications, as biomaterials for embolic devices in minimally invasive surgery

RECONSTITUTED RECOMBINANT PHENOL HYDROXYLASE FROM P. STUTZERI OX1

Aerobic bacterial degradation of aromatic hydrocarbons is generally divided into two major routes, the so-called upper pathway, which leads to the formation of partially oxidized aromatic intermediates, and a lower pathway, which uses dihydroxylated aromatic molecules. These activated aromatic compounds undergo ring cleavage reactions and are further processed to give molecules that can eventually enter the citric acid cycle. Monooxygenases are key enzymes in the upper pathway and catalyze hydroxylation of the aromatic ring at different positions Pseudomonas stutzeri OX1 is able to grow on a wide spectrum of aromatics, including phenol, cresols, and dimethylphenols, but also on nonhydroxylated molecules such as toluene, o-xylene, and benzene. Two different monooxygenases have been found in the genome of P. stutzeri OX1, phenol hydroxylase (PH) (1) and toluene o-xylene monooxygenase (ToMO)