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Here, we aimed at the preparation of an antibacterial surface on a flexible polydimethylsiloxane substrate. The polydimethylsiloxane surface was sputtered with silver, deposited with carbon, heat treated and exposed to excimer laser, and the combinations of these steps were studied. Our main aim was to find the combination of techniques applicable both against Gram-positive and Gram-negative bacteria. The surface morphology of the structures was determined by atomic force microscopy and scanning electron microscopy. Changes in surface chemistry were conducted by application of X-ray photoelectron spectroscopy and energy dispersive spectroscopy. The changes in surface wettability were characterized by surface free energy determination. The heat treatment was also applied to selected samples to study the influence of the process on layer stability and formation of PDMS-Ag or PDMS-C-Ag composite layer. Plasmon resonance effect was determined for as-sputtered and heat-treated Ag on polydimethylsiloxane. The heating of such structures may induce formation of a pattern with a surface plasmon resonance effect, which may also significantly affect the antibacterial activity. We have implemented sputtering of the carbon base layer in combination with excimer laser exposure of PDMS/C/Ag to modify its properties. We have confirmed that deposition of primary carbon layer on PDMS, followed by sputtering of silver combined with subsequent heat treatment and activation of such surface with excimer laser, led to the formation of a surface with strong antibacterial properties against two bacterial strains of S. epidermidis and E. coli.

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A polydimethylsiloxane (PDMS) composite with multi-walled carbon nanotubes was successfully prepared. Composite foils were treated with both plasma and excimer laser, and changes in their physicochemical properties were determined in detail. Mainly changes in surface chemistry, wettability, and morphology were determined. The plasma treatment of PDMS complemented with subsequent heating led to the formation of a unique wrinkle-like pattern. The impact of different laser treatment conditions on the composite surface was determined. The morphology was determined by AFM and LCM techniques, while chemical changes and chemical surface mapping were studied with the EDS/EDX method. Selected activated polymer composites were used for the evaluation of antibacterial activity using Gram-positive (Staphylococcus epidermidis) and Gram-negative (Escherichia coli) bacteria. The antibacterial effect was achieved against S. epidermidis on pristine PDMS treated with 500 mJ of laser energy and PDMS-C nanocomposite treated with a lower laser fluence of 250 mJ. Silver deposition of PDMS foil increases significantly its antibacterial properties against E. coli, which is further enhanced by the carbon predeposition or high-energy laser treatment.

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This study involved the preparation and characterization of structures with a honeycomb-like pattern (HCP) formed using the phase separation method using a solution mixture of chloroform and methanol together with cellulose acetate. Fluorinated ethylene propylene modified by plasma treatment was used as a suitable substrate for the formation of the HCP structures. Further, we modified the HCP structures using silver sputtering (discontinuous Ag nanoparticles) or by adding Ag nanoparticles in PEG into the cellulose acetate solution. The material morphology was then determined using atomic force microscopy (AFM) and scanning electron microscopy (SEM), while the material surface chemistry was studied using energy dispersive spectroscopy (EDS) and wettability was analyzed with goniometry. The AFM and SEM results revealed that the surface morphology of pristine HCP with hexagonal pores changed after additional sample modification with Ag, both via the addition of nanoparticles and sputtering, accompanied with an increase in the roughness of the PEG-doped samples, which was caused by the high molecular weight of PEG and its gel-like structure. The highest amount (approx. 25 at %) of fluorine was detected using the EDS method on the sample with an HCP-like structure, while the lowest amount (0.08%) was measured on the PEG + Ag sample, which revealed the covering of the substrate with biopolymer (the greater fluorine extent means more of the fluorinated substrate is exposed). As expected, the thickness of the Ag layer on the HCP surface depended on the length of sputtering (either 150 s or 500 s). The sputtering times for Ag (150 s and 500 s) corresponded to layers with heights of about 8 nm (3.9 at % of Ag) and 22 nm (10.8 at % of Ag), respectively. In addition, we evaluated the antibacterial potential of the prepared substrate using two bacterial strains, one Gram-positive of S. epidermidis and one Gram-negative of E. coli. The most effective method for the construction of antibacterial surfaces was determined to be sputtering (150 s) of a silver nanolayer onto a HCP-like cellulose structure, which proved to have excellent antibacterial properties against both G+ and G- bacterial strains.

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The aim of our research was to study the behaviour of adipose tissue-derived stem cells (ADSCs) and vascular smooth muscle cells (VSMCs) on variously modified poly(L-lactide) (PLLA) foils, namely on pristine PLLA, plasma-treated PLLA, PLLA grafted with polyethylene glycol (PEG), PLLA grafted with dextran (Dex), and the tissue culture polystyrene (PS) control. On these materials, the ADSCs were biochemically differentiated towards VSMCs by a medium supplemented with TGFß1, BMP4 and ascorbic acid (i.e. differentiation medium). ADSCs cultured in a non-differentiation medium were used as a negative control. Mature VSMCs cultured in both types of medium were used as a positive control. The impact of the variously modified PLLA foils and/or differences in the composition of the medium were studied with reference to cell adhesion, growth and differentiation. We observed similar adhesion and growth of ADSCs on all PLLA samples when they were cultured in the non-differentiation medium. The differentiation medium supported the expression of specific early, mid-term and/or late markers of differentiation (i.e. type I collagen, αSMA, calponin, smoothelin, and smooth muscle myosin heavy chain) in ADSCs on all tested samples. Moreover, ADSCs cultured in the differentiation medium revealed significant differences in cell growth among the samples that were similar to the differences observed in the cultures of VSMCs. The round morphology of the VSMCs indicated worse adhesion to pristine PLLA, and this sample was also characterized by the lowest cell proliferation. Culturing VSMCs in the differentiation medium inhibited their metabolic activity and reduced the cell numbers. Both cell types formed the most stable monolayer on plasma-treated PLLA and on the PS control. The behaviour of ADSCs and VSMCs on the tested PLLA foils differed according to the specific cell type and culture conditions. The suitable biocompatibility of both cell types on the tested PLLA foils seems to be favourable for vascular tissue engineering purposes.

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Surface modification is an important step in making a synthetic polymer cytocompatible. We have previously reported improved cytocompatibility of immortalized human keratinocytes (HaCaT) with the otherwise bioinert fluorinated ethylene propylene (FEP) upon treatment with argon plasma discharge. In this article, we show that FEP modified with Ar plasma with the power of 3 and 8 W for 40 and 240 s served as a suitable material for cultivation of primary human dermal fibroblasts (HDF), which showed significantly improved proliferation and spreading comparable to standard tissue culture polystyrene. We also evaluated focal adhesions formed by HDF cells on modified FEP, which were far more numerous compared to pristine FEP. Moreover, we attempted spontaneous osteogenic differentiation of adipose-derived mesenchymal stem cells modified with human telomerase reverse transcriptase on Ar plasma-modified FEP. While the spontaneous osteogenic differentiation was unsuccessful, the cells were able to adhere and differentiated on tested matrices upon the administration of osteodifferentiation medium. These combined findings suggest that the treatment of FEP with Ar plasma comprises and efficient method to enable the adhesion and proliferation of various cell types on an otherwise largely bioinert material.

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Stem cells can be defined as units of biological organization that are responsible for the development and the regeneration of organ and tissue systems. They are able to renew their populations and to differentiate into multiple cell lineages. Therefore, these cells have great potential in advanced tissue engineering and cell therapies. When seeded on synthetic or nature-derived scaffolds in vitro, stem cells can be differentiated towards the desired phenotype by an appropriate composition, by an appropriate architecture, and by appropriate physicochemical and mechanical properties of the scaffolds, particularly if the scaffold properties are combined with a suitable composition of cell culture media, and with suitable mechanical, electrical or magnetic stimulation. For cell therapy, stem cells can be injected directly into damaged tissues and organs in vivo. Since the regenerative effect of stem cells is based mainly on the autocrine production of growth factors, immunomodulators and other bioactive molecules stored in extracellular vesicles, these structures can be isolated and used instead of cells for a novel therapeutic approach called "stem cell-based cell-free therapy". There are four main sources of stem cells, i.e. embryonic tissues, fetal tissues, adult tissues and differentiated somatic cells after they have been genetically reprogrammed, which are referred to as induced pluripotent stem cells (iPSCs). Although adult stem cells have lower potency than the other three stem cell types, i.e. they are capable of differentiating into only a limited quantity of specific cell types, these cells are able to overcome the ethical and legal issues accompanying the application of embryonic and fetal stem cells and the mutational effects associated with iPSCs. Moreover, adult stem cells can be used in autogenous form. These cells are present in practically all tissues in the organism. However, adipose tissue seems to be the most advantageous tissue from which to isolate them, because of its abundancy, its subcutaneous location, and the need for less invasive techniques. Adipose tissue-derived stem cells (ASCs) are therefore considered highly promising in present-day regenerative medicine.

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Since the last decade, tissue engineering has shown a sensational promise in providing more viable alternatives to surgical procedures for harvested tissues, implants and prostheses. Biomedical polymers, such as low-density polyethylene (LDPE), high-density polyethylene (HDPE) and ultra-high molecular weight polyethylene (UHMWPE), were activated by Ar plasma discharge. Degradation of polymer chains was examined by determination of the thickness of ablated layer. The amount of an ablated polymer layer was measured by gravimetry. Contact angle, measured by goniometry, was studied as a function of plasma exposure and post-exposure aging times. Chemical structure of modified polymers was characterized by angle resolved X-ray photoelectron spectroscopy. Surface chemistry and polarity of the samples were investigated by electrokinetic analysis. Changes in surface morphology were followed using atomic force microscopy. Cytocompatibility of plasma activated polyethylene foils was studied using two distinct model cell lines; VSMCs (vascular smooth muscle cells) as a model for vascular graft testing and connective tissue cells L929 (mouse fibroblasts) approved for standardized material cytotoxicity testing. Specifically, the cell number, morphology, and metabolic activity of the adhered and proliferated cells on the polyethylene matrices were studied in vitro. It was found that the plasma treatment caused ablation of the polymers, resulting in dramatic changes in their surface morphology and roughness. ARXPS and electrokinetic measurements revealed oxidation of the polymer surface. It was found that plasma activation has a positive effect on the adhesion and proliferation of VSMCs and L929 cells.

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The field of material surface modification with the aim of biomaterial construction involves several approaches of treatments that allow the preparation of materials, which positively influence adhesion of cells and their proliferation and thus aid and improve tissue formation. Modified materials have a surface composition and morphology intended to interact with biological systems and cellular functions. Not only surface chemistry has an effect on material biological response, surface structures of different morphology can be constructed to guide a desirable biological outcome. Nano-patterned material surfaces have been tested with the aim of how surface geometry and physical properties on a micro- and nano-scale can affect cellular response and influence cell adhesion and proliferation. Biological functionality of solid state substrates was significantly improved by the irradiation of material with plasma discharge or laser treatment. Commonly used "artificial" polymers (e.g. polyethylene (PE), polystyrene (PS), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), polyethylene naphthalate (PEN)) and biopolymers (e.g. Poly-l-Lactic acid (PLLA), polymethylpentene (PMP)) were treated with aim of biocompatibility improvement. The treatment of polymer/biopolymer substrates leads to formation of ripple or wrinkle-like structures, supported also with heat treatment or other subsequent surface processing. Several types of chemically different substances (e.g. metal or carbon nano-particles, proteins) were grafted onto material surfaces or built into material structures by different processes. Surface physico-chemical properties (e.g. chemistry, charge, morphology, wettability, electrical conductivity, optical and mechanical properties) of treated surfaces were determined. The enhancement of adhesion and proliferation of cells on modified substrates was investigated in vitro. Bactericidal action of noble metal nano-particles (e.g. Au, Ag) on polymers was characterized. The influence of metal nano-particle grafting by using metal nano-particle suspension prepared by "green" methods was determined. Micro- and nano-patterned surfaces can be constructed as tissue scaffolds with specific functions regarding cell adhesion and proliferation or potential biosensor applications.

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In this work, an influence of bovine serum albumin proteins grafting on the surface properties of plasma-treated polyethylene and poly-l-lactic acid was studied. The interaction of the vascular smooth muscle cells with the modified polymer surface was determined. The surface properties were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, nano-LC-ESI-Q-TOF mass spectrometry, electrokinetic analysis, and goniometry. One of the motivations for this work is the idea that by the interaction of the cell with substrate surface, the proteins will form an interlayer between the cell and the substrate. It was proven that when interacting with the plasma-treated high-density polyethylene and poly-l-lactic acid, the bovine serum albumin protein is grafted on the polymer surface. Since the proteins are bonded to the substrate surface, they can stimulate cell adhesion and proliferation.

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Silver nanolayers were sputtered on polytetrafluoroethylene (PTFE) and subsequently transformed into discrete nanoislands by thermal annealing. The Ag/PTFE composites prepared under different conditions were characterized by several complementary methods (goniometry, UV-visible spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy), and new data on the mechanism of Ag layer growth and Ag atom clustering under annealing were obtained. Biocompatibility of selected Ag/PTFE composites was studied in vitro using vascular smooth muscle cell (VSMC) cultures. Despite of the well-known inhibitory properties of silver nanostructures towards broad spectrum of bacterial strains and cells, it was found that very thin silver coating stimulates both adhesion and proliferation of VSMCs.

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The cell-material interface plays a crucial role in the interaction of cells with synthetic materials for biomedical use. The application of plasma for tailoring polymer surfaces is of abiding interest and holds a great promise in biomedicine. In this paper, we describe polyethylene (PE) surface tuning by Ar plasma irradiating and subsequent grafting of the chemically active PE surface with adhesive proteins or motives to support cell attachment. These simple modifications resulted in changed polymer surface hydrophilicity, roughness and morphology, which we thoroughly characterized. The effect of our modifications on adhesion and growth was tested in vitro using mouse embryonic fibroblasts (NIH 3T3 cell line). We demonstrate that the plasma treatment of PE had a positive effect on the adhesion, spreading, homogeneity of distribution and moderately on proliferation activity of NIH 3T3 cells. This effect was even more pronounced on PE coated with biomolecules.

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Properties of gold films sputtered under different conditions onto borosilicate glass substrate were studied. Mean thickness of sputtered gold film was measured by gravimetry, and film contact angle was determined by goniometry. Surface morphology was examined by atomic force microscopy, and electrical sheet resistance was determined by two-point technique. The samples were seeded with rat vascular smooth muscle cells, and their adhesion and proliferation were studied. Gold depositions lead to dramatical changes in the surface morphology and roughness in comparison to pristine substrate. For sputtered gold structures, the rapid decline of the sheet resistance appears on structures deposited for the times above 100 s. The thickness of deposited gold nanoparticles/layer is an increasing function of sputtering time and current. AFM images prove the creation of separated gold islands in the initial deposition phase and a continuous gold coverage for longer deposition times. Gold deposition has a positive effect on the proliferation of vascular smooth muscle cells. Largest number of cells was observed on sample sputtered with gold for 20 s and at the discharge current of 40 mA. This sample exhibits lowest contact angle, low relative roughness, and only mild increase of electrical conductivity.

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Cell colonization of synthetic polymers can be regulated by physical and chemical modifications of the polymer surface. High-density and low-density polyethylene (HDPE and LDPE) were therefore activated with Ar⁺ plasma and grafted with fibronectin (Fn) or bovine serum albumin (BSA). The water drop contact angle usually decreased on the plasma-treated samples, due to the formation of oxidized groups, and this decrease was inversely related to the plasma exposure time (50-300 s). The presence of nitrogen and sulfur on the polymer surface, revealed by X-ray photoelectron spectroscopy (XPS), and also by immunofluorescence staining, showed that Fn and BSA were bound to this surface, particularly to HDPE. Plasma modification and grafting with Fn and BSA increased the nanoscale surface roughness of the polymer. This was mainly manifested on HDPE. Plasma treatment and grafting with Fn or BSA improved the adhesion and growth of vascular smooth muscle cells in a serum-supplemented medium. The final cell population densities on day 6 after seeding were on an average higher on LDPE than on HDPE. In a serum-free medium, BSA grafted to the polymer surface hampered cell adhesion. Thus, the cell behavior on polyethylene can be modulated by its type, intensity of plasma modification, grafting with biomolecules, and composition of the culture medium.