Blood Coagulation Activities of Cotton-Alginate-Copper Composites.

Alginate-based materials have gained significant attention in the medical industry due to their biochemical properties. In this article, we aimed to synthesize Cotton-Alginate-Copper Composite Materials (COT-Alg(-)Cu(2+)). The main purpose of this study was to assess the biochemical properties of new composites in the area of blood plasma coagulation processes, including activated partial thromboplastin time (aPTT), prothrombin time (PT), and thrombin time (TT). This study also involved in vitro antimicrobial activity evaluation of materials against representative colonies of Gram-positive and Gram-negative bacteria and antifungal susceptibility tests. The materials were prepared by immersing cotton fibers in an aqueous solution of sodium alginate, followed by ionic cross-linking of alginate chains within the fibers with Cu(II) ions to yield antimicrobial activity. The results showed that the obtained cotton-alginate-copper composites were promising materials to be used in biomedical applications, e.g., wound dressing.

Coating Methods of Carbon Nonwovens with Cross-Linked Hyaluronic Acid and Its Conjugates with BMP Fragments.

The cross-linking of polysaccharides is a universal approach to affect their structure and physical properties. Both physical and chemical methods are used for this purpose. Although chemical cross-linking provides good thermal and mechanical stability for the final products, the compounds used as stabilizers can affect the integrity of the cross-linked substances or have toxic properties that limit the applicability of the final products. These risks might be mitigated by using physically cross-linked gels. In the present study, we attempted to obtain hybrid materials based on carbon nonwovens with a layer of cross-linked hyaluronan and peptides that are fragments of bone morphogenetic proteins (BMPs). A variety of cross-linking procedures and cross-linking agents (1,4-butanediamine, citric acid, and BDDE) were tested to find the most optimal method to coat the hydrophobic carbon nonwovens with a hydrophilic hyaluronic acid (HA) layer. Both the use of hyaluronic acid chemically modified with BMP fragments and a physical modification approach (layer-by-layer method) were proposed. The obtained hybrid materials were tested with the spectrometric (MALDI-TOF MS) and spectroscopic methods (IR and 1H-NMR). It was found that the chemical cross-linking of polysaccharides is an effective method for the deposition of a polar active substance on the surface of a hydrophobic carbon nonwoven fabric and that the final material is highly biocompatible.

Poly(lactic acid)/Zinc/Alginate Complex Material: Preparation and Antimicrobial Properties.

The aim of this study was to investigate an antimicrobial and degradable composite material consisting of melt-blown poly(lactic acid) nonwoven fabrics, alginate, and zinc. This paper describes the method of preparation and the characterization of the physicochemical and antimicrobial properties of the new fibrous composite material. The procedure consists of fabrication of nonwoven fabric and two steps of dip-coating modification: (1) impregnation of nonwoven samples in the solution of alginic sodium salt and (2) immersion in a solution of zinc (II) chloride. The characterization and analysis of new material included scanning electron microscopy (SEM), specific surface area (SSA), and total/average pore volume (BET). The polylactide/alginate/Zn fibrous composite were subjected to microbial activity tests against colonies of Gram-positive (Staphylococcus aureus), Gram-negative (Escherichia coli) bacterial strains, and the following fungal strains: Aspergillus niger van Tieghem and Chaetomium globosum. These results lay a technical foundation for the development and potential application of new composite as an antibacterial/antifungal material in biomedical areas.

Chemical Modification as a Method of Improving Biocompatibility of Carbon Nonwovens.

It was shown that carbon nonwoven fabrics obtained from polyacrylonitrile fibers (PAN) by thermal conversion may be modified on the surface in order to improve their biological compatibility and cellular response, which is particularly important in the regeneration of bone or cartilage tissue. Surface functionalization of carbon nonwovens containing C-C double bonds was carried out using in situ generated diazonium salts derived from aromatic amines containing both electron-acceptor and electron-donor substituents. It was shown that the modification method characteristic for materials containing aromatic structures may be successfully applied to the functionalization of carbon materials. The effectiveness of the surface modification of carbon nonwoven fabrics was confirmed by the FTIR method using an ATR device. The proposed approach allows the incorporation of various functional groups on the nonwovens' surface, which affects the morphology of fibers as well as their physicochemical properties (wettability). The introduction of a carboxyl group on the surface of nonwoven fabrics, in a reaction with 4-aminobenzoic acid, became a starting point for further modifications necessary for the attachment of RGD-type peptides facilitating cell adhesion to the surface of materials. The surface modification reduced the wettability (θ) of the carbon nonwoven by about 50%. The surface free energy (SFE) in the chemically modified and reference nonwovens remained similar, with the surface modification causing an increase in the polar component (ɣp). The modification of the fiber surface was heterogeneous in nature; however, it provided an attractive site of cell-materials interaction by contacting them to the fiber surface, which supports the adhesion process.

Effects of Process Parameters on Structure and Properties of Melt-Blown Poly(Lactic Acid) Nonwovens for Skin Regeneration.

Skin regeneration requires a three-dimensional (3D) scaffold for cell adhesion, growth and proliferation. A type of the scaffold offering a 3D structure is a nonwoven material produced via a melt-blown technique. Process parameters of this technique can be adapted to improve the cellular response. Polylactic acid (PLA) was used to produce a nonwoven scaffold by a melt-blown technique. The key process parameters, i.e., the head and air temperature, were changed in the range from 180-270 °C to obtain eight different materials (MB1-MB8). The relationships between the process parameters, morphology, porosity, thermal properties and the cellular response were explored in this study. The mean fiber diameters ranged from 3 to 120 µm. The average material roughness values were between 47 and 160 µm, whereas the pore diameters ranged from 5 to 400 µm. The calorimetry thermograms revealed a correlation between the temperature parameters and crystallization. The response of keratinocytes and macrophages exhibited a higher cell viability on thicker fibers. The cell-scaffold interaction was observed via SEM after 7 days. This result proved that the features of melt-blown nonwoven scaffolds depended on the processing parameters, such as head temperature and air temperature. Thanks to examinations, the most suitable scaffolds for skin tissue regeneration were selected.

Physical Properties, Chemical Analysis, and Evaluation of Antimicrobial Response of New Polylactide/Alginate/Copper Composite Materials.

In recent years, due to an expansion of antibiotic-resistant microorganisms, there has been growing interest in biodegradable and antibacterial polymers that can be used in selected biomedical applications. The present work describes the synthesis of antimicrobial polylactide-copper alginate (PLA-ALG-Cu2+) composite fibers and their characterization. The composites were prepared by immersing PLA fibers in aqueous solution of sodium alginate, followed by ionic cross-linking of alginate chains within the polylactide fibers with Cu(II) ions to yield PLA-ALG-Cu2+ composite fibers. The composites, so prepared, were characterized by scanning electron microscopy (SEM), UV/VIS transmittance and attenuated total reflection Fourier-transform infrared spectroscopy ATR-FTIR, and by determination of their specific surface area (SSA), total/average pore volumes (through application of the 5-point Brunauer-Emmett-Teller method (BET)), and ability to block UV radiation (determination of the ultraviolet protection factor (UPF) of samples). The composites were also subjected to in vitro antimicrobial activity evaluation tests against colonies of Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria and antifungal susceptibility tests against Aspergillus niger and Chaetomium globosum fungal mold species. All the results obtained in this work showed that the obtained composites were promising materials to be used as an antimicrobial wound dressing.

Conjugates of Copper Alginate with Arginine-Glycine-Aspartic Acid (RGD) for Potential Use in Regenerative Medicine.

Current restrictions on the use of antibiotics, associated with increases in bacterial resistance, require new solutions, including materials with antibacterial properties. In this study, copper alginate fibers obtained using the classic wet method were used to make nonwovens which were modified with arginine-glycine-aspartic acid (RGD) derivatives. Stable polysaccharide-peptide conjugates formed by coupling with 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium toluene-4-sulfonate (DMT/NMM/TosO-), and materials with physically embedded RGD derivatives, were obtained. The materials were found to be characterized by very high antibacterial activity against S. aureus and K. pneumoniae. Cytotoxicity studies confirmed that the materials are not cytotoxic. Copper alginate conjugates with RGD peptides have strong potential for use in regenerative medicine, due to their biocompatibility and innate antibacterial activity.

Analysis of structure and properties of antibacterial vascular patch used in abdominal aorta aneurysm surgeries.

BACKGROUND: Biocompatible materials are used for treatment of blood circulatory system diseases, especially abdominal aortic aneurysms. The most popular and often used are knitted and polymer vascular patches. The aim of this study was to optimize the manufacturing process of implantable materials, ensuring antibacterial activity useful for treating abdominal aorta aneurysms. METHODS: The vascular patch was manufactured from Trevira® yarn. The parameters of the intermediate product and vascular patch were tested according to standard procedures. RESULTS: The vascular patch, manufactured from microsilver-containing yarn, with crimps on the surface of the patch, has been found useful for treatment of abdominal aorta aneurysms. Introducing crimps on the surface of the patch resulted in reduction of water permeability and enabled cutting of the graft at various angles without fraying at the cut ends of the biomaterial. The final vascular patch was marked by a gradual release of silver within 48 hours. CONCLUSIONS: On the basis of the performed test, it has been demonstrated that an implantable material for the treatment of abdominal aorta aneurysms was obtained, and that it can be considered as an alternative for currently used vascular patches. The final vascular patch was marked by a gradual release of silver during the first period of incubation. The antibacterial properties of the final product were confirmed by observation of a significant reduction in the number of Staphylococcus aureus and Klebsiella pneumoniae bacterial colonies.

Anti-bacterial materials based on hyaluronic acid: Selection of research methodology and analysis of their anti-bacterial properties.

In the frame of the presented research, highly-porous structures made of hyaluronic acid modified with bioactive compounds were prepared. The method of microbiological testing of hygroscopic materials has been elaborated by verification of the JIS L 1902:2002 and ASTM E2149-13a test methods. The research has shown that the method developed in accordance with ASTM E2149-13a is suitable for testing the activity of hyaluronic acid samples against bacteria. E. coli and S. aureus. In the case of E. coli it is preferred to use as a medium the phosphoric buffer and for S. aureus NaCl solution from NB. By analysing the results of the antibacterial properties, it is important to note that the introduction of a small amount of zinc and zinc oxide in the matrix from the hyaluronic acid (in the amount of 3% by weight of the polymer) makes it possible to obtain a material with a strong activity against the bacterial strains. It enables to use this type of material as a treatment for hard-to-treat, infected wounds. On the other hand, using a relatively small dose of the cephalosporin antibiotic did not result in high levels of activity against the bacteria Gram "+" and Gram "-".

Search for Fibrous Aggregates Potentially Useful in Regenerative Medicine Formed under Physiological Conditions by Self-Assembling Short Peptides Containing Two Identical Aromatic Amino Acid Residues.

This study investigates the propensity of short peptides to self-organize and the influence of aggregates on cell cultures. The dipeptides were derived from both enantiomers of identical aromatic amino acids and tripeptides were prepared from two identical aromatic amino acids with one cysteine or methionine residue in the C-terminal, N-terminal, or central position. The formation or absence of fibrous structures under physiological conditions was established using Congo Red and Thioflavine T assays as well as by microscopic examination using normal and polarized light. The in vitro stability of the aggregates in buffered saline solution was assessed over 30 days. Materials with potential for use in regenerative medicine were selected based on the cytotoxicity of the peptides to the endothelial cell line EA.hy 926 and the wettability of the surfaces of the films, as well as using scanning electron microscopy. The criteria were fulfilled by H-dPhedPhe-OH, H-dCysdPhedPhe-OH, H-CysTyrTyr-OH, H-dPhedPhedCys-OH, H-TyrTyrMet-OH, and H-TyrMetTyr-OH. Our preliminary results suggest that the morphology and cell viability of L919 fibroblast cells do not depend on the stereochemistry of the self-organizing peptides.

Biodegradable intramedullary nails reinforced with carbon and alginate fibers: In vitro and in vivo biocompatibility.

BACKGROUND: Commonly, intramedullary nails are made of nondegradable materials, and hence they need to be removed once the bone fracture is healed. We propose a novel composite material consisting of poly-L-lactide matrix modified with carbon and alginate fibers to be used for biodegradable intramedullary fixation. The aim of this study was to make in vitro and in vivo biocompatibility assessments. METHODS: In the in vitro conditions, biocompatibility of biomaterials was compared using normal human osteoblasts. After 3 and 7 days, cytotoxicity, viability and proliferation tests were performed, as well as cell morphology and adhesion observations. In the in vivo experiments, Californian rabbits (approx. 9 months old) were used. The composite nails and controls (Kirschner wires) were used for fixation of distal femoral osteotomy. The evaluation was made on the basis of clinical observations, radiographs taken after 2, 4, 6 and 8 weeks post implantation, and macroscopic and histological observations. RESULTS: Cell tests indicated that both modifiers had a positive influence on cell viability. Biodegradable composite nails led to bony union when used for fixation of distal diaphysis osteotomy in rabbits. Histological analysis showed that the initial focal necrosis should be fully compensated for by the osteoblast proliferation and trabeculae formation. CONCLUSIONS: Both in vitro and in vivo tests confirmed biocompatibility and potential applicability of novel biodegradable intramedullary nails modified with long carbon and alginate fibers for osteosynthesis of bone epiphysis.

Influence of the intramedullary nail preparation method on nail's mechanical properties and degradation rate.

When it comes to the treatment of long bone fractures, scientists are still investigating new materials for intramedullary nails and different manufacturing methods. Some of the most promising materials used in the field are resorbable polymers and their composites, especially since there is a wide range of potential manufacturing and processing methods. The aim of this work was to select the best manufacturing method and technological parameters to obtain multiphase, and multifunctional, biodegradable intramedullary nails. All composites were based on a poly(l-lactide) matrix. Either magnesium alloy wires or carbon and alginate fibres were introduced in order to reinforce the nails. The polylactide matrix was also modified with tricalcium phosphate and gentamicin sulfate. The composite nails were manufactured using three different methods: forming from solution, injection moulding and hot pressing. The effect of each method of manufacturing on mechanical properties and degradation rate of the nails was evaluated. The study showed that injection moulding provides higher uniformity and homogeneity of the particle-modified polylactide matrix, whereas hot pressing favours applying higher volume fractions of fibres and their better impregnation with the polymer matrix. Thus, it was concluded that the fabrication method should be individually selected dependently on the nail's desired phase composition.

Gentamicin release from biodegradable poly-l-lactide based composites for novel intramedullary nails.

One of the major problems in orthopedic surgery is infection associated with implantation. The treatment is a very difficult and long-term process. A solution to this issue can be the use of implants which additionally constitute an antibiotic carrier preventing the development of an infection. Prototypes of biodegradable intramedullary nails made of three different composites with a poly(L-lactide) matrix were designed. The nails served as gentamicin sulfate (GS) carrier - an antibiotic commonly used in the treatment of osteomyelitis. The matrix was reinforced with carbon fibers (CF), alginate fibers (Alg) and magnesium alloy wires (Mg), as well as modified with bioactive particles of tricalcium phosphate (TCP) in various systems. In this way, novel, multi-phase and multifunctional degradable intramedullary nails were obtained. The tests demonstrated strong dependence between the type of the modifying phase introduced into the composite, and the rate of drug release. Introduction of gentamicin into the nail structure strengthened and prolonged antibacterial activity of the nails.

Fibrous polymeric composites based on alginate fibres and fibres made of poly-ε-caprolactone and dibutyryl chitin for use in regenerative medicine.

This work concerns the production of fibrous composite materials based on biodegradable polymers such as alginate, dibutyryl chitin (DBC) and poly-ε-caprolactone (PCL). For the production of fibres from these polymers, various spinning methods were used in order to obtain composite materials of different composition and structure. In the case of alginate fibres containing the nanoadditive tricalcium phosphate (TCP), the traditional method of forming fibres wet from solution was used. However in the case of the other two polymers the electrospinning method was used. Two model systems were tested for biocompatibility. The physicochemical and basic biological tests carried out show that the submicron fibres produced using PCL and DBC have good biocompatibility. The proposed hybrid systems composed of micrometric fibres (zinc and calcium alginates containing TCP) and submicron fibres (DBC and PCL) meet the requirements of regenerative medicine. The biomimetic fibre system, the presence of TCP nanoadditive, and the use of polymers with different resorption times provide a framework with specific properties on which bone cells are able to settle and proliferate.