Here, the layer-by-layer technique (LbL) was used to modify glass as model biomaterial with multilayers of chitosan and heparin to control the interaction with MG-63 osteoblast-like cells. Different pH values during multilayer formation were applied to control their physico-chemical properties. In the absence of adhesive proteins like plasma fibronectin (pFN) both plain layers were rather cytophobic. Hence, the preadsorption of pFN was used to enhance cell adhesion which was strongly dependent on pH. Comparing the adhesion promoting effects of pFN with an engineered repeat of the FN III fragment and collagen I which both lack a heparin binding domain it was found that multilayers could bind pFN specifically because only this protein was capable of promoting cell adhesion. Multilayer surfaces that inhibited MG-63 adhesion did also cause a decreased cell growth in the presence of serum, while an enhanced adhesion of cells was connected to an improved cell growth.

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A polyclonal antibody against the beta 1 subunit of the fibronectin (FN) receptor was used to mimic the early events of integrin receptor functioning to study the initial cellular processes during the organization of FN matrix on biomaterials. Hydrophilic glass and hydrophobic octadecylsilane (ODS) surfaces have been applied as models for different biocompatible materials. By immunofluorescence we could demonstrate that FN receptors organize on the dorsal cell surface of adhering fibroblasts in a specific linear pattern along with actin filaments, but only if the cells were attached to hydrophilic glass. In contrast, FN receptors were not reorganized on hydrophobic octadecylsilane (ODS). In parallel experiments, FN matrix formation after 72 h of incubation on the same substrata has been analyzed microscopically, and quantified by cell ELISA, in order to be further correlated with the integrin receptor functioning in contact with the biomaterials. It was found that FN structuring and the amount of FN matrix have been significantly diminished on ODS that was related to the observed changes in integrin receptor functioning. To learn more about the mechanism of this phenomenon, desorption of 125I-FN from these substrata was studied and found to be significantly decreased on hydrophobic ODS. As a consequence, FN receptor (function) might be arrested on the ventral cell surface, thus the important role of beta 1 integrins in the positional organization of the FN matrix may be disturbed. In light of these facts, antibody-induced clustering of FN receptor can be considered as a useful model for studying the early steps of FN matrix formation on biomaterials.

The development of a bioartificial skin is a step toward the treatment of patients with deep burns or nonhealing skin ulcers. One possible approach is based on growing dermal cells on membranes to obtain appropriate living cellular stroma (sheets) to cover the wound. New membrane-forming copolymers were synthesized, based on acrylonitrile (AN) copolymerization with hydrophilic N-vinylpyrrolidone (NVP) monomer, in different percentage ratios, such as 5, 20, and 30% w/w, and with two other relatively high polar comonomers--namely, sodium 2-methyl-2-propene-1-sulfonic acid (NaMAS) and aminoethylmethacrylate (AeMA). All these copolymers were characterized for their bulk composition and number average molecular weight, and used to prepare ultrafiltration membranes. Water contact angles and water uptake were estimated to characterize the wettability and scanning force microscopy to visualize the morphology of the resulting polymer surface. Cytotoxicity was estimated according to the international standard regulations, and the materials were found to be nontoxic. The interaction of the membranes with human skin fibroblasts was investigated considering that these cells are among the first to colonize membranes upon implantation or with prolonged external contact. The overall cell morphology, formation of focal adhesion contacts, and cell proliferation were estimated to characterize the cell material interactions. It was found that the pure polyacrylonitrile homopolymer (PAN) membrane provides excellent conditions for seeding with fibroblasts, comparable only to a copolymer containing AeMA. In contrast, the presence of NaMAS with acidic ionic groups decreased both the attachment and proliferation of fibroblasts. Low content of NVP in the copolymer, up to about 5%, still enabled good attachment and spreading of cells, as well as subsequent proliferation of fibroblasts, but higher ratios of 20 and 30% resulted in a significant decrease of these cellular activities.

Recently, nanodiamonds (NDs) have attracted great interest due to their unique physical and chemical properties that could be used in various biological applications. However, depending on the origin, NDs often contain different impurities which may affect cellular functions and viability. Therefore, before their biomedical application, the cytotoxicity of newly produced NDs should be assessed.In the present study, we have evaluated cytotoxicity of four types of ND particles with two cell models: a human osteosarcoma cell line, MG-63, and primary rat mesenchymal stem cells (rMSCs). Detonation-generated nanodiamond (DND) particles were purified with different acid oxidizers and impurities’ content was determined by elemental analysis. The particles size distribution was measured revealing that the DND particles have an average size in the range of 51–233 nm. Cytotoxicity was assessed by optical microscopy and proliferation assay after 72 hours exposure of the cells to nanoparticles. We observed cell-specific and material-specific toxicity for all tested particles. Primary stem cells demonstrated higher sensitivity to DND particles than osteosarcoma cells. The most toxic were the DND particles with the smallest grain size and slight content of non-diamond carbon, while DNDs with higher grain size and free from impurities had no significant influence on cell proliferation and morphology. In addition, the smaller DND particles were found to form large aggregates mainly during incubation with rMSCs. These results demonstrate the role of the purification method on the properties of DND particles and their cytotoxicity as well as the importance of cell types used for evaluation of the nanomaterials.

In this paper the effect of surface wettability on hepatocyte morphology and function was studied, using clean and octadecylsylane (ODS)-coated glass as a model for hydrophilic and hydrophobic surfaces, respectively. C3A cells--a hepatoblastoma cell line, and freshly obtained porcine hepatocytes were cultured for a short-time period of up to 4 days on the above substrata. Hepatocyte adhesive interactions were characterized monitoring the initial cell attachment, the overall cell morphology, the formation of focal adhesions, and actin filaments. Since hepatocytes showed a clear tendency for homotypic adhesion on ODS, specific E-cadherin staining was used to visualize the intercellular contacts by immunofluorescence microscopy. Additionally, functional assays were carried out to monitor proliferation, metabolic activity, and albumin synthesis of C3A cells. It could be shown that both C3A cells and normal porcine hepatocytes spread better on hydrophilic glass; spreading being accompanied by the development of pronounced actin stress fibers and focal adhesion contacts. In contrast, on hydrophobic substrata predominant cell-cell interactions took place which led to intense E-cadherin staining in the intercellular contacts of porcine hepatocytes but not in C3A cells. On the other hand, metabolic activity and growth of C3A cells were reduced on hydrophobic ODS, but albumin synthesis was similar on both surfaces. It was concluded that the wettability of materials has a strong influence on the attachment and morphology of hepatocytes while the influence of surface properties on the functional activity of hepatocytes still remains to be elucidated.

Nanotechnology-based drug delivery systems for cancer therapy are the topic of interest for many researchers and scientists. Graphene oxide (GO) and its derivates are among the most extensively studied delivery systems of this type. The increased surface area, elevated loading capacity, and aptitude for surface functionalization together with the ability to induce reactive oxygen species make GO a promising tool for the development of novel anticancer therapies. Moreover, GO nanoparticles not only function as effective drug carriers but also have the potential to exert their own inhibitory effects on tumour cells. Recent results show that the functionalization of GO with different functional groups, namely, with amine groups, leads to increased reactivity of the nanoparticles. The last steers different hypotheses for the mechanisms through which this functionalization of GO could potentially lead to improved anticancer capacity. In this research, we have evaluated the potential of amine-functionalized graphene oxide nanoparticles (GO-NH2) as new molecules for colorectal cancer therapy. For the purpose, we have assessed the impact of aminated graphene oxide (GO) sheets on the viability of colon cancer cells, their potential to generate ROS, and their potential to influence cellular proliferation and survival. In order to elucidate their mechanism of action on the cellular systems, we have probed their genotoxic and cytostatic properties and compared them to pristine GO. Our results revealed that both GO samples (pristine and aminated) were composed of few-layer sheets with different particle sizes, zeta potential, and surface characteristics. Furthermore, we have detected increased cyto- and genotoxicity of the aminated GO nanoparticles following 24-hour exposure on Colon 26 cells. The last leads us to conclude that exposure of cancer cells to GO, namely, aminated GO, can significantly contribute to cancer cell killing by enhancing the cytotoxicity effect exerted through the induction of ROS, subsequent DNA damage, and apoptosis.