Composition Polymeric Membranes Based on the VDF-TeFE Copolymer Formed by Electrospinning

The paper presents the results of pilot studies on the formation of non-woven hydrophilic piezoelectric composite polymer membranes based on a copolymer of vinylidene fluoride and tetrafluoroethylene (VDF-TeFE) and polyethenylpyrrolidine (PEP) by electrospinning. Using optical goniometry, the effect of the PEP content on the wetting of the membrane surface with water was established. Using scanning electron microscopy, the influence of the content PEP on the structure of the formed membranes was studied. The effect of an isotonic NaCl solution on the structure of the formed membranes upon their dissolution within 7 days was studied. Based on studies of the chemical composition of the membranes before and after their dissolution, an assumption was made about the possibility of using the developed membranes for targeted delivery of pharmacological preparations for wound healing

PLLA scaffold modification using magnetron sputtering of the copper target to provide antibacterial properties

Using the electrospinning method, we produced biodegradable scaffolds from poly-l-lactide acid polymer (PLLA - poly-l-lactide acid). Using DC magnetron sputtering of the copper target we modified the surface of the scaffolds. For investigate scaffolds morphology, structure and elemental composition were used scanning electron microscopy, X-ray diffraction and X-ray fluorescence analysis. The results of scanning electron microscopy reveal that scaffolds consist of chaotically located fibres. The diameters of fibres range from 0.8 to 2 μm. Initially amorphous scaffold after modification has crystalline structure. The count of oxygen and copper with modification is increased, but count of carbon decreased. For the investigation of the scaffolds wetting ability were used glycerol and water. The wetting angles for the both liquids were similarly comparable. The values for the wetting angles range from 114 ± 5° to 125 ± 5°, what indicated that scaffolds had hydrophobic properties. Testing for antibacterial features indicated that the modified scaffolds are capable to have a bacteriostatic effect. Compared to the number of bacteria cultured without scaffold (11.8 ± 1.26 CFU×104/ml), two modified samples have bacteriostatic properties (reducing the number of bacteria on 30 and 50%). Economically effective method PLLA scaffolds modification could be used for creating low-cost wound dressings with antibacterial properties

Nonwoven PTFE Membranes Fabricated by Electrospinning Method: Preparation and Characterization

Polytetrafluoroethylene (PTFE) is one of the promising materials for the purposes of tissue engineering and chemical technology because of its excellent physico-chemical properties and mechanical characteristics. However, conventional methods of PTFE porous membranes production have several disadvantages which limit the number of potential application areas by reason of a insufficient surface-to-volume ratio and poor porosity at small thickness. In the paper the results of using PTFE water suspension with a solution of water-soluble polymer for preparation of porous membranes by electrospinning are reported. The physico-chemical characteristics of membranes were investigated depending on the content of PTFE dispersion in spinning solution. There were found high hydrophobicity and lyophilicity of PTFE electrospun membranes. Main reasons of poor mechanical properties of porous membranes at high content of PTFE suspension in spinning solution are discovered. The ways of mechanical properties improvement and areas of possible applications are proposed

Hybrid calcium phosphate coatings for implants

Monophasic biomaterials cannot provide all the necessary functions of bones or other calcined tissues. It is necessary to create for cancer patients the multiphase materials with the structure and composition simulating the natural bone. Such materials are classified as hybrid, obtained by a combination of chemically different components. The paper presents the physical, chemical and biological studies of coatings produced by hybrid technologies (HT), which combine primer layer and calcium phosphate (CaP) coating. The first HT type combines the method of vacuum arc titanium primer layer deposition on a stainless steel substrate with the following micro-arc oxidation (MAO) in phosphoric acid solution with addition of calcium compounds to achieve high supersaturated state. MAO CaP coatings feature high porosity (2-8%, pore size 5-7 [mu]m) and surface morphology with the thickness greater than 5 [mu]m. The thickness of Ti primer layer is 5-40 [mu]m. Amorphous MAO CaP coating micro-hardness was measured at maximum normal load F[max]=300 mN. It was 3.1±0.8 GPa, surface layer elasticity modulus E=110±20 GPa, roughness R[a]=0.9±0.1 [mu]m, R[z]=7.5±0.2 [mu]m, which is less than the titanium primer layer roughness. Hybrid MAO CaP coating is biocompatible, able to form calcium phosphates from supersaturated body fluid (SBF) solution and also stimulates osteoinduction processes. The second HT type includes the oxide layer formation by thermal oxidation and then CaP target radio frequency magnetron sputtering (RFMS). Oxide-RFMS CaP coating is a thin dense coating with good adhesion to the substrate material, which can be used for metal implants. The RFMS CaP coating has thickness 1.6±0.1 [mu]m and consists of main target elements calcium and phosphorus and Ca/P ratio 2.4. The second HT type can form calcium phosphates from SBF solution. In vivo study shows that hybrid RFMS CaP coatingis biocompatible and produces fibrointegration processes

Application of atomic force microscopy methods for testing the surface parameters of coatings of medical implants

Atomic force microscopy methods are used to study calcium phosphate coatings that are formed on surfaces of various materials, which are used in medicine, by radio-frequency magnetron sputtering of a hydroxyapatite target. The roughness parameters and values of the surface potentials of metal, polymer, and hybrid substrates are determined in a semicontact regime. Calcium phosphate coatings increase the roughness of surfaces of polymer and metal materials, thus presenting a stimulating factor for the attachment and proliferation of osteogenic cells. Using the Kelvin method, it is shown that calcium phosphate coatings change the surface potential of substrates

Comparison of the Influence of "Solvent/Non-Solvent” Treatment for the Attachment of Signal Molecules on the Structure of Electrospun PCL and PLLA Biodegradable Scaffolds

Electrospun biodegradable scaffolds (matrixes) made of poly([epsilon]-caprolactone) (PCL) and poly(L-lactic acid) (PLLA) are three-dimensional fibrous structures that are commonly used in regenerative medicine and drug delivery systems. Modification of such structures allows manipulating with biological and immune response. Previously, our team suggested a number of surface modification strategies for thin films made of PLLA. One of the proposed strategies are based on treatment of the material with “solvent/non-solvent” mixture that allows absorbing biologically active molecules or linkers on the surface of the sample. The aim of this work was to compare the influence of “solvent/non-solvent” treatment on the structure and crystallinity of the elecrospun biodegradable PCL and PLLA scaffolds. For that purpose, original PCL and PLLA scaffolds were treated with mixture of toluene and ethanol in different proportions. Morphology of the obtained samples was studied using scanning electron microscopy. It was shown that “solvent/non-solvent” treatment doesn’t lead to changes in scaffolds morphology such as gluing or cutting of the matrix fibers. By means of X-ray diffraction analysis it was shown that treatment of the samples with selected mixtures doesn’t change material crystallinity. Thus, it was demonstrated that proposed composition of the “solvent/nonsolvent” mixture can be used for the modification of electrospun PCL and PLLA scaffolds

Effect of annealing on mechanical and morphological properties of Poly(L-lactic acid)/Hydroxyapatite composite as material for 3D printing of bone tissue growth stimulating implants

In this work, effect of additional annealing on mechanical and morphological properties of 3D-printed PLLA/HAp composite scaffolds of three compositions (12.5, 25, and 50 wt.% of HAp) was investigated. Morphology and Young's modulus of 3D-printed scaffolds were investigated by scanning electron microscopy and nanoindentation. It has been shown that additional annealing does not have an effect on the homogeneous distribution of HAp powder in the PLLA-matrix. Results of nanoindentation showed growth of Young's modulus after annealing. The maximum value of 9393 ± 709 MPa Young's modulus was reached for the annealed composite with 50 wt.% of HAp