Natural and synthetic polymers for wounds and burns dressing

This study investigated the influence of surface wettability on competitive protein adsorption and the initial attachment of osteoblasts. A thin-film coating of hexamethyldisiloxane (HMDSO) and subsequent O(2)-plasma treatment was carried out on substrates with a mirror surface in order to create a wide range of wettabilities. The adsorption behavior of fibronectin (Fn) and albumin (Alb) in both individual and competitive mode, and the initial attachment of mouse osteoblastic cells (MC3T3-E1) over a wide range of wettabilities were investigated. The contact angle of HMDSO coatings without O(2)-plasma treatment against double-distilled water was more than 100 degrees, whereas it dramatically decreased after the O(2)-plasma treatment to almost 0 degrees, resulting in super-hydrophilicity. Individually, Fn adsorption showed a biphasic inclination, whereas Alb showed greater adsorption to hydrophobic surfaces. In the competitive mode, in a solution containing both Fn and Alb, Fn showed greater adsorption on hydrophilic surfaces, whereas Alb predominantly adsorbed on hydrophobic surfaces. The initial attachment of osteoblastic cells increased with an increase in surface wettability, in particular, on a super-hydrophilic surface, which correlated well with Fn adsorption in the competitive mode. These results suggest that Fn adsorption may be responsible for increasing cell adhesion on hydrophilic surfaces in a body fluid or culture media under physiological conditions.

https://iopscience.iop.org/article/10.1088/1748-6041/4/4/045002/pdf

Influence of surface wettability on competitive protein adsorption and initial attachment of osteoblasts

Over centuries, the field of regenerative skin tissue engineering has had several advancements to facilitate faster wound healing and thereby restoration of skin. Skin tissue regeneration is mainly based on the use of suitable scaffold matrices. There are several scaffold types, such as porous, fibrous, microsphere, hydrogel, composite and acellular, etc., with discrete advantages and disadvantages. These scaffolds are either made up of highly biocompatible natural biomaterials, such as collagen, chitosan, etc., or synthetic materials, such as polycaprolactone (PCL), and poly-ethylene-glycol (PEG), etc. Composite scaffolds, which are a combination of natural or synthetic biomaterials, are highly biocompatible with improved tensile strength for effective skin tissue regeneration. Appropriate knowledge of the properties, advantages and disadvantages of various biomaterials and scaffolds will accelerate the production of suitable scaffolds for skin tissue regeneration applications. At the same time, emphasis on some of the leading challenges in the field of skin tissue engineering, such as cell interaction with scaffolds, faster cellular proliferation/differentiation, and vascularization of engineered tissues, is inevitable. In this review, we discuss various types of scaffolding approaches and biomaterials used in the field of skin tissue engineering and more importantly their future prospects in skin tissue regeneration efforts.

https://www.mdpi.com/1422-0067/17/12/1974/pdf

Future Prospects for Scaffolding Methods and Biomaterials in Skin Tissue Engineering: A Review

Chemical crosslinking of biopolymeric scaffolds: Current knowledge and future directions of crosslinked engineered bone scaffolds

Evaluation of Cross-Linking Methods for Electrospun Gelatin on Cell Growth and Viability

Gelatin is a natural polymer used in pharmaceutical and medical applications, especially in the production of biocompatible and biodegradable wound dressings and drug delivery systems. Gelatin granules hydrate, swell and solubilize in water, and rapidly degrade in vivo. The durability of these materials could, however, be prolonged by cross-linking by aldehydes, carbodiimides, and aldose sugars, but the biocompatibility of collagenous biomaterials is profoundly influenced by the nature and extent of cross-linking. In this study, gelatin sponges were prepared by using various cross-linkers such as glutaraldehyde (GA), 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDAC), and D-fructose. The effects of the type and the amount of cross-linker on thermal and mechanical properties, stability, and cytotoxicity were investigated. The mechanical analysis data showed that an increase in the amount of GA in the sponge structures caused a slight increase in the modulus of elasticity but had almost no effect on the tensile strength. Increase in the EDAC concentration produced a maximum in the modulus of elasticity and tensile strength values. The stability of the sponges and the time required for complete degradation in aqueous media increased in parallel with the cross-linker content. In vitro studies carried out with fibroblast cells demonstrated a higher cell viability for the samples cross-linked with low concentrations of GA than for those cross-linked with EDAC.

http://www.neoderm.com.tr/files/Cytotoxicity-evaluation-of-gelatin-sponges-prepared-with-dif.pdf

Cytotoxicity evaluation of gelatin sponges prepared with different cross-linking agents.

Thermal and mechanical properties of hydroxyapatite impregnated acrylic bone cements

Polyurethane membranes were prepared under nitrogen atmosphere by using various proportions of toluene diisocyanates (TDI) and polypropylene-ethylene glycol (P) with addition of no other ingredients such as catalysts, initiator or solvent in order to achieve medical purity. Effects of composition on mechanical properties were examined. In general, modulus and UTS values demonstrated an increase and PSBR demonstrated a decrease as the TDI/Polyol ratio of the polymer increased. Elastic modulus, ultimate tensile strength (UTS) and per cent strain before rupture (PSBR) values were found to be in the range of 1.4–5.4 MPa, 0.9–1.9 MPa, and 60.4–99.7%, respectively. Surfaces of the membranes were modified by oxygen plasma applying glow-discharge technique and the effect of applied plasma power (10 W or 100 W, 15 min) on surface hydrophilicity and on the attachment of Vero cells were studied. Water contact angle values of the plasma modified surfaces varied between 67° and 46°, demonstrating a decrease as the applied plasma power was increased. The unmodified material had 42–45 cells attached per cm2. It was observed that as the applied power increased the number of attached cells first increased (60–70 cells/cm2 at 10 W) and then decreased (27–40 cells/cm2 at 100 W). These demonstrated that surface properties of polyurethanes can be modified by plasma-glow discharge technique to achieve the optimum levels of cell attachment.

Oxygen plasma modification of polyurethane membranes.

Self-curing acrylic cements, consisting mainly of polymethylmethacrylate (PMMA), are widely used in dentistry and orthopedic surgery. One of the major side effects of the standard PMMA application is tissue necrosis at the bone-cement interface due to the rise of temperature during the polymerization reaction. This may also lead to aseptic loosening over time. Therefore, intense research is being carried out in the development of bone cements with new compositions. In this study, the aim was to develop new bone cement compositions that would have low setting temperature and high mechanical strength and be comparable with the commercially available ones. For this purpose, PMMA bone cements having various amounts of hydroxyapatite were prepared. In order to obtain a proper and homogeneous distribution of hydroxyapatite particles within the cement, very low-viscosity PMMA bone-cement compositions were developed. The addition of hydroxyapatite decreased the polymerization temperature (from 111iC to 87iC) and increased the compressive strength (from 110 MPa to 122 MPa) of the resultant cements. These new bone cements have setting temperatures and mechanical strengths comparable with commercially available cements and are believed to be more biocompatible since hydroxyapatite is a natural mineral present in the bone structure.

/pdf/mechanical-and-thermal-properties-of-hydroxyapatite-3ha8c4jpqj.pdf

Mechanical and Thermal Properties of Hydroxyapatite-Impregnated Bone Cement

There is a very delicate relation between the amounts of all the ingredients present in the cement composition and the properties of the product. In this study, homogeneous poly(methyl methacrylate) (PMMA) microspheres were prepared by suspension polymerization technique, and used in cement formulations. Various acrylic cements with different compositions were prepared by using PMMA microspheres, methyl methacrylate (MMA) monomer, radiopaque agent of barium sulfate (BaSO4), inorganic particles of hydroxyapatite (HA), initiator and chain stopping agent of 1-dodecyl mercaptan (DDM). The effects of these additives on mechanical and thermal properties of the resultant cements were examined. Addition of 8% HA relative to the solid parts caused an increase in both tensile and compressive strengths from 20.40 to 25.20 MPa, and from 84.04 to 89.57 MPa, respectively, while curing temperature was decreased about 3 degrees. Chain stopping agent of DDM caused a sharp decrease about 30 degrees in the curing temperature. Radiopaque agent of barium sulfate caused inverse effect on mechanical and thermal properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Kemal Serbetci

Papers

Cytotoxicity evaluation of gelatin sponges prepared with different cross-linking agents.

Thermal and mechanical properties of hydroxyapatite impregnated acrylic bone cements

Oxygen plasma modification of polyurethane membranes.

Mechanical and Thermal Properties of Hydroxyapatite-Impregnated Bone Cement

Effects of ingredients on thermal and mechanical properties of acrylic bone cements