Surface Modification of Polylactic Acid Films by Atmospheric Pressure Plasma Treatment

A new approach for the modification of polylactic acid (PLA) materials using atmospheric pressure plasma (APP) is described. PLA films plasma exposure time was 20, 60, 120 s. The surface morphology and wettability of the obtained PLA films were investigated by atomic force microscopy (AFM) and the sitting drop method. The atmospheric pressure plasma increased the roughness and surface energy of PLA film. The wettability of PLA has been improved with the application of an atmospheric plasma surface treatment. It was shown that it is possible to obtain PLA films with various surface relief and tunable wettability. Additionally, we demonstrated that the use of cold atmospheric pressure plasma for surface activation allows for the immobilization of bioactive compounds like hyaluronic acid (HA) on the surface of obtained films. It was shown that composite PLA-HA films have an increased long-term hydrophilicity of the films surface

Influence of the high-power ion-beam irradiation of a hydroxyapatite target on the properties of formed calcium phosphate coatings

The physical-mechanical of properties of biocompatible calcium phosphate coatings deposited onto titanium and silicon substrates from erosion materials, which are generated by irradiating hydroxyapatite (synthetic and natural) targets by means of the high-power pulsed ion beam of a Temp-4 accelerator, are investigated. A calculation technique for predicting the rate and energy efficiency of deposition using pulsed ion beams is proposed. Their characteristics are analyzed as applied to the formation of calcium phosphate coatings

Comparison of titanium mesh implants with PLA-hydroxyapatite coatings for maxillofacial cancer reconstruction

Since 2013 physics of TPU and oncologists from the TCRI with participation of the “ConMet” company (Moscow) and the “Sintel” company (Tomsk Special Economic Zone resident) have been working on the theme entitled “Development of the composite implants for reconstructive surgery of a craniofacial areas of the traumatological and oncological patients” supported with the Federal Program ”R&D, part 1.3”. The goal was to develop the maxillo-facial implants on the basis of the transformable titanium mesh with PLA & hydroxyapatite coating. According to the Contract No. 14.578.21.0031, the team of developers had to start supplying these advanced implants to the industrial partners up to 2017. This research was supported with the preliminary market researches by the ISPMS SB RAS and the TP “MF”. The stages of preliminary market researches were: 1) research of the Worldwide CMF market; 2) forecasting the BRIC CMF market up to 2020; 3) the total Russian market (epidemiology) estimation as a sum of official calculations and statistics; 4) looking for the best foreign analogue prices, comparing their and our implant properties; 5) search for the best Russian analogues; 6) the investigation of the world patent databaseEspacenet for the last years, and finding the owners and applicants of patents of CMF osteosynthesis plates on the basis of titanium coated with PLA & hydroxyapatite; 7) comparison of the domestic implants, and making conclusions. Several variants of the meshes have got the equal quality with the best foreign and Russian implants. The closest analogues were titanium, polyethylene, PEEK composite meshes suited to the patient shape by the Synthes company in 2014, and the only hybrid titanium "Grey" implant with layers of gelatin, dextran, collagen, HAP & BMP-2 was found. This implant was produced by Russian institution, and it was mentioned in the report on clinical trials by L.A. Pavlova et al., 2014 [1]. There are no manufacturers of the coated implants in Russia. The average price of the similar foreign implants varies from 12 up to 4

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

Comparative Studies of the Physical, Mechanical and Chemical Properties of Hybrid Coatings for Medical Implants

In the work the physical, mechanical and chemical properties of oxide and calcium-phosphate coatings formed by the microarc oxidation and radio-frequency magnetron sputtering methods, or their combination were studied. It is shown that combining the advantages of various technologies enables one to obtain a wide range of hybrid coatings used for various strategies of osteosynthesis. The calcium phosphate coatings obtained by the radio-frequency magnetron sputtering methods were chosen as coatings on cortical screws. The hybrid coatings obtained by a combination of microarc oxidation method and radio-frequency magnetron sputtering method were recommended for intramedullary implants. For extramedullary implants, the most optimal coatings are the coatings formed by radio-frequency magnetron sputtering with an intermediate TiO[2] sublayer

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

Dissolution testing for prolonged-release solid dosage form containing drug substances degrading in test media. Application to polymeric delivery systems of paracetamol

Synthetic biodegradable polymers are widely used as materials for the targeted drug delivery and controlled release devices. In order to control the rate of drug release from polymer scaffolds surface ordinary dissolution testing is performed. It includes placing a device into testing media, taking probes at determined time and estimating the drug concentration. As for prolonged release the issue is the drug degradation in test media what leads to false interpretation of results. This study was focused on the investigation of paracetamol degradation in phosphate buffer saline media for three days and its effect on the results of polymeric drug delivery system dissolution test. It was shown, that relative error in the released drug concentration evaluation can rise up to 34% depending on the exposure time and the initial probe concentration. An approach of experimental results correction is proposed

Dissolution testing for prolonged-release solid dosage form containing drug substances degrading in test media. Application to polymeric delivery systems of paracetamol

Synthetic biodegradable polymers are widely used as materials for the targeted drug delivery and controlled release devices. In order to control the rate of drug release from polymer scaffolds surface ordinary dissolution testing is performed. It includes placing a device into testing media, taking probes at determined time and estimating the drug concentration. As for prolonged release the issue is the drug degradation in test media what leads to false interpretation of results. This study was focused on the investigation of paracetamol degradation in phosphate buffer saline media for three days and its effect on the results of polymeric drug delivery system dissolution test. It was shown, that relative error in the released drug concentration evaluation can rise up to 34% depending on the exposure time and the initial probe concentration. An approach of experimental results correction is 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

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