Developing a biomaterial interface based on poly(lactic acid) via plasma-assisted covalent anchorage of D-glucosamine and its potential for tissue regeneration

The aim of this study was to develop the potential tissue engineering applications of D-glucosamine (GlcN) immobilized onto the surface of a biodegradable matrix in order to induce a desired biological effect at biointerfaces. Thus, for sample preparation we used a novel multistep physicochemical approach. In the first step the poly(lactic acid) (PLA) films were exposed to a low pressure plasma in air atmosphere, followed by radical graft copolymerization with acrylic acid to yield a carboxyl-functionalized spacer layer on the PLA surface. The carboxyl groups were then coupled to GlcN molecules via the carbodiimide chemistry. The developed surfaces were characterized by X-ray Photoelectron Spectroscopy (XPS), Contact angle measurements and Atomic Force Microscopy (AFM). A preliminary study on the proliferation of fibroblasts on the developed surfaces was performed using the NIH/3T3 cell line. © 2016 Elsevier B.V.ARRS, Slovenian Research AgencyMinistry of Education, Youth and Sports of the Czech Republic [LO1504]; Ministry of Education, Science, Research and Sport of the Slovak Republic; Slovak Academy of Sciences [2/0199/14]; Slovenian Research Agency [P2-0082

The chemical stability and cytotoxicity of carbonyl iron particles grafted with poly(glycidyl methacrylate) and the magnetorheological activity of their suspensions

Carbonyl iron (CI) particles were grafted with poly(glycidyl methacrylate) (PGMA) using atom transfer radical polymerization. Compact coating of PGMA largely improved the chemical stability of the particles in an acid environment and thus reduced the common drawback of bare CI particles. Furthermore, due to possible medical applications of CI-polymer systems for magnetic drug targeting, an in vitro cytotoxicity test was performed using an NIH/3T3 cell line. The cell viability was evaluated by spectrometric assay (MTT). The results show that the prepared particles are not cytotoxic. Moreover, bare CI particles as well as synthesized core-shell particles were suspended in silicone oil, and the rheological behavior of MR suspensions was investigated in controlled shear rate mode under various magnetic field strengths. Dynamic yield stress as a measure of the rigidity of the created internal structures of the suspensions was determined using the Herschel-Bulkley model, which provided a reasonably good fit for rheological data. MR suspensions of PGMA-coated particles exhibited only slightly decreased yield stresses due to their negligibly-affected magnetic performance. This journal is © The Royal Society of Chemistry.Operational Program Research and Development for Innovations - European Regional Development Fund (ERDF); National Budget of the Czech Republic [CZ.1.05/2.1.00/03.0111]; TBU in Zlin [IGA/CPS/2015/007]; Centre of Excellence FUN-MAT; Czech Science Foundation [13-08944S

Formulation of magneto-responsive hydrogels from dually cross-linked polysaccharides: Synthesis, tuning and evaluation of rheological properties

Smart hydrogels based on natural polymers present an opportunity to fabricate responsive scaffolds that provide an immediate and reversible reaction to a given stimulus. Modulation of mechanical characteristics is especially interesting in myocyte cultivation, and can be achieved by magnetically controlled stiffening. Here, hyaluronan hydrogels with carbonyl iron particles as a magnetic filler are prepared in a low-toxicity process. Desired mechanical behaviour is achieved using a combination of two cross-linking routes-dynamic Schiff base linkages and ionic cross-linking. We found that gelation time is greatly affected by polymer chain conformation. This factor can surpass the influence of the number of reactive sites, shortening gelation from 5 h to 20 min. Ionic cross-linking efficiency increased with the number of carboxyl groups and led to the storage modulus reaching 10(3) Pa compared to 10(1) Pa-10(2) Pa for gels cross-linked with only Schiff bases. Furthermore, the ability of magnetic particles to induce significant stiffening of the hydrogel through the magnetorheological effect is confirmed, as a 10(3)-times higher storage modulus is achieved in an external magnetic field of 842 kA.m(-1). Finally, cytotoxicity testing confirms the ability to produce hydrogels that provide over 75% relative cell viability. Therefore, dual cross-linked hyaluronan-based magneto-responsive hydrogels present a potential material for on-demand mechanically tunable scaffolds usable in myocyte cultivation.project OP RDE Junior Grants of TBU in Zlin [CZ.02.2.69/0.0/0.0/19_073/0016941]; TBU in Zlin [IGA/CPS/2022/001]; Ministry of Education, Youth and Sports of the Czech Republic-DKRVO [RP/CPS/2022/003]; Ministry of Education, Youth and Sports of the Czech Republic project-DKRVO [RP/CPS/2022/001

Blood coagulation and platelet adhesion on polyaniline films

Polyaniline is a promising conducting polymer with still increasing application potential in biomedicine. Its surface modification can be an efficient way how to introduce desired functional groups and to control its properties while keeping the bulk characteristics of the material unchanged. The purpose of the study was to synthetize thin films of pristine conducting polyaniline hydrochloride, non-conducting polyaniline base and polyaniline modified with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA) and investigate chosen parameters of their hemocompatibility. The modification was performed either by introduction of PAMPSA during the synthesis or by reprotonation of polyaniline base. The polyaniline hydrochloride and polyaniline base had no impact on blood coagulation and platelet adhesion. By contrast, the polyaniline reprotonated with PAMPSA completely hindered coagulation thanks to its interaction with coagulation factors Xa, Va and IIa. The significantly lower platelets adhesion was also found on this surface. Moreover, this film maintains its conductivity at pH of 6, which is an improvement in comparison with standard polyaniline hydrochloride losing most of its conductivity at pH of 4. Polyaniline film with PAMPSA introduced during synthesis had an impact on platelet adhesion but not on coagulation. The combined conductivity, anticoagulation activity, low platelet adhesion and improved conductivity at pH closer to physiological, open up new possibilities for application of polyaniline reprotonated by PAMPSA in blood-contacting devices, such as catheters or blood vessel grafts. © 2015 Elsevier B.V..Czech Science Foundation [13-08944S]; Ministry of Education, Youth and Sport of the Czech Republic [CZ.1.05/2.1.00/03.0111]; TBU in Zlin [IGA/FT/2014/004

Cytotoxicity of colloidal polyaniline dispersions

Cytotoxic effects of colloidal polyaniline dispersions with the particles in the nano-size region (226.5 +/- 5.5 nm) and standard polyaniline powder has been investigated and compared. The mouse embryonic fibroblast cell line (NIH/3T3) was used in the test and the cell viability was detected by MTT assay. The results indicate that concentration of 0.5 % (m/m) of colloidal polyaniline dispersion, corresponding to 90 mu g/mL polyaniline polymer in culture medium is a critical in terms of cell viability. This is higher threshold for cytotoxicity when compared with a standard polyaniline powder, for which the onset of cytotoxicity was observed at concentration of 35 mu g/mL.13-08944S, GACR, Czech Science Foundatio

Antibacterial properties of polyaniline-silver films

In situ polymerised thin polyaniline (PANI) films produced on polystyrene dishes were tested for their antibacterial activity with respect to Escherichia coli and Staphylococcus aureus, representing both gram-positive and gram-negative bacteria. PANI films were subsequently used for the reduction of silver ions to metallic Ag. PANI salt and base in original forms and after the deposition of Ag were studied. PANI salt showed a significant antibacterial effect against both bacteria strains while the efficacy of neat PANI base was only marginal. After the Ag deposition, the PANI base exhibited different levels of antibacterial effect depending on the type of the bacterial strain; the growth of gram-positive Staphylococcus aureus was inhibited depending on the Ag concentration on the film, while Escherichia coli remained uninfluenced. Efficacy of the PANI salt with deposited Ag against both bacteria strains was comparable with that of PANI alone and was not affected by the Ag concentration. The results show that Ag deposition can be a suitable method for the preparation of PANI base films with improved antibacterial properties. (C) 2013 Institute of Chemistry, Slovak Academy of Science

Edible flowers - antioxidant activity and impact on cell viability

The phenolic compound composition, antioxidant activity and impact on cell viability of edible flower extracts of Allium schoenoprasum; Bellis perennis; Cichorium intybus; Rumex acetosa; Salvia pratensis; Sambucus nigra; Taraxacum officinale; Tragopogon pratensis; Trifolium repens and Viola arvensis was examined for the first time. Total phenolic content of the flowers of these plants fell between 11.72 and 42.74 mg of tannin equivalents/kg of dry matter. Antioxidant activity ranged from 35.56 to 71.62 g of ascorbic acid equivalents/kg of dry matter. Using the Human Hepatocellular Carcinoma cell-line (HepG2) and the Human Immortalized Non-tumorigenic Keratinocyte cell line (HaCaT), we assessed cell viability following a 3 day incubation period in media containing 25, 50, 75 and 100 μg/ml of total phenolic compounds using a colorimetric MTT assay. These three properties could make the herbs useful in treatment of various diseases like cancer. The tested extracts had significant effects on cell viability, but the effects were dependent not only on the phenolic compound concentration and the edible flowers species, but also on the phenolic compound and antioxidant profiles. In addition, responses differed between cell lines. © 2013 Versita Warsaw and Springer-Verlag Wien

Cell proliferation on a conducting polymer (polyaniline)

Polyaniline (PANI) belongs to a group of conducting polymers that show numerous properties useful in biomedical applications. Although PANT has long been studied in terms of interaction with human tissue, the published studies are mostly focused on composites of polyaniline with other polymers, not allowing for generalization of the obtained results. The present study is focused on the adhesion of human liver cells to a conducting and non-conducting polyaniline films. The ability of human liver cells to attach to both types of the tested surfaces was confirmed. Cell proliferation on the PANI surfaces was monitored in relation to material biocompatibility and to its practical applications. The results showed statistically significant differences in cell proliferation depending on the type of PANT film. The study thus points out the need to test materials in their neat forms, which allow for better generalization of the test results leading to their broader applications

Non-toxic polyester urethanes based on poly(lactic acid), poly(ethylene glycol) and lysine diisocyanate

Poly(lactic acid)-based polymers are highly suitable for temporary biomedical applications, such as tissue support or drug delivery systems. Copolymers of different molecular weight based on poly(lactic acid) and poly(ethylene glycol) were prepared by polycondensation, catalysed by hydrochloric acid. A chain-extension reaction with l-lysine ethyl ester diisocyanate was employed afterwards to obtain polyester urethanes with enhanced properties. The GPC results showed that the molecular weights of the products reached about 50,000gmol(-1) and the hydrolytic progress was rapid in the first 2weeks; the drop in M-n equalled approximately 70%. Additionally, elemental analysis of the buffer medium proved that hydrolytic degradation was more rapid in the first stage. Tensile-strength testing revealed that ductility increased alongside reduced molecular weight of poly(ethylene glycol), also suggesting that polymer branching occurred due to side reactions of isocyanate. Based on the envisaged biomedical applications for these polymers, cytotoxicity tests were carried out and the cytotoxic effect was only moderate in the case of 100% polymer extract prepared according to ISO standard 10993-12. In their research, the authors focused on preparing metal-free, catalysed synthesis of polyester urethanes, which could prove useful to numerous biomedical applications.Czech Science Foundation [15-08287Y]; European Regional Development Fund [CZ.1.05/2.1.00/19.0409]; Ministry of Education, Youth and Sports of the Czech Republic [LO1504]CZ.1.05/2.1.00/19.0409, ERDF, European Regional Development Fun

A novel multistep method for chondroitin sulphate immobilization and its interaction with fibroblast cells

Polymeric biomaterials are widely used in medical applications owing to their low cost, processability and sufficient toughness. Surface modification by creating a thin film of bioactive agents is promising technique to enhance cellular interactions, regulate the protein adsorption and/or avoid bacterial infections. Polyethylene is one of the most used polymeric biomaterial but its hydrophobic nature impedes its further chemical modifications. Plasma treatment is unique method to increase its hydrophilicity by incorporating hydrophilic oxidative functional groups and tailoring the surface by physical etching. Furthermore, grafting of polymer brushes of amine group containing monomers onto the functionalized surface lead to strongly immobilized bioactive agents at the final step. Chondroitin sulphate is natural polysaccharide mainly found in connective cartilage tissue which used as a bioactive agent to immobilize onto polyethylene surface by multistep method in this study. © 2016 Elsevier B.V.LO1504, MŠMT, Ministry of Education, Youth and SportsOperational Program Research and Development for Innovations; European Regional Development Fund (ERDF); national budget of Czech Republic [CZ.1.05/2.1.00/03.0111]; Ministry of Education, Youth and Sports of the Czech Republic [LO1504