Comprehensive Assessment of Graphene Oxide Nanoparticles: Effects on Liver Enzymes and Cardiovascular System in Animal Models and Skeletal Muscle Cells.

The growing interest in graphene oxide (GO) for different biomedical applications requires thoroughly examining its safety. Therefore, there is an urgent need for reliable data on how GO nanoparticles affect healthy cells and organs. In the current work, we adopted a comprehensive approach to assess the influence of GO and its polyethylene glycol-modified form (GO-PEG) under near-infrared (NIR) exposure on several biological aspects. We evaluated the contractility of isolated frog hearts, the activity of two rat liver enzymes-mitochondrial ATPase and diamine oxidase (DAO), and the production of reactive oxygen species (ROS) in C2C12 skeletal muscle cells following direct exposure to GO nanoparticles. The aim was to study the influence of GO nanoparticles at multiple levels-organ; cellular; and subcellular-to provide a broader understanding of their effects. Our data demonstrated that GO and GO-PEG negatively affect heart contractility in frogs, inducing stronger arrhythmic contractions. They increased ROS production in C2C12 myoblasts, whose effects diminished after NIR irradiation. Both nanoparticles in the rat liver significantly stimulated DAO activity, with amplification of this effect after NIR irradiation. GO did not uncouple intact rat liver mitochondria but caused a concentration-dependent decline in ATPase activity in freeze/thaw mitochondria. This multifaceted investigation provides crucial insights into GOs potential for diverse implications in biological systems.

Old age as a risk factor for liver diseases: Modern therapeutic approaches.

Recent scientific interest has been directed towards age-related diseases, driven by the significant increase in global life expectancy and the growing population of individuals aged 65 and above. The ageing process encompasses various biological, physiological, environmental, psychological, behavioural, and social changes, leading to an augmented susceptibility to chronic illnesses. Cardiovascular, neurological, musculoskeletal, liver and oncological diseases are prevalent in the elderly. Moreover, ageing individuals demonstrate reduced regenerative capacity and decreased tolerance towards therapeutic interventions, including organ transplantation. Liver diseases, such as non-alcoholic fatty liver disease, alcoholic liver disease, hepatitis, fibrosis, and cirrhosis, have emerged as significant public health concerns. Paradoxically, these conditions remain underestimated despite their substantial global impact. Age-related factors are closely associated with the severity and unfavorable prognosis of various liver diseases, warranting further investigation to enhance clinical management and develop novel therapeutic strategies. This comprehensive review focuses specifically on age-related liver diseases, their treatment strategies, and contemporary practices. It provides a detailed account of the global burden, types, molecular mechanisms, and epigenetic alterations underlying these liver pathologies.

Small Heterocyclic Ligands as Anticancer Agents: QSAR with a Model G-Quadruplex.

G-quadruplexes (GQs) have become valid targets for anticancer studies in recent decades due to their multifaceted biological function. Herewith, we aim to quantify interactions of potential heterocyclic ligands (Ls) with model GQs. For seven 4-aminoquinazolines and three 2-heteroaryl perimidines, seven of this ten-membered group so far unknown, we use routine quantum chemical modeling. As shown in the literature, a preferred mode of interaction of heterocycles with cellular structures is stacking to exposable faces of G-quadruplexes. To exploit the energy of this interaction as a molecular descriptor and achieve the necessary chemical precision, we use state of the art large-scale density functional theory (DFT) calculations of stacked heterocycles to a GQ. Actually, the GQ has been simplified for the computation by stripping it off all pentose phosphate residues into a naked model of stacked guanine quartets. The described model thus becomes computable. The obtained heterocyclic ligand GQ.L stacking energies, that is, their GQ affinities, are the necessary ligand descriptors. Using the ligand biological inhibitory activities (IC50) on a human malignant melanoma A375 cell line, we obtain a good linear relationship between computed ligand stacking affinities to GQ, and experimental log (IC50) values. Based on the latter relationship, we discuss a putative mechanism of anticancer activity of heterocyclic ligands via stacking interactions with GQs and thereby controlling cell regulatory activity. This mechanism may tentatively be applied to other condensed five- and six-membered small heterocycles as well.

Promising Therapeutic Strategies for Colorectal Cancer Treatment Based on Nanomaterials.

Colorectal cancer (CRC) is a global health problem responsible for 10% of all cancer incidences and 9.4% of all cancer deaths worldwide. The number of new cases increases per annum, whereas the lack of effective therapies highlights the need for novel therapeutic approaches. Conventional treatment methods, such as surgery, chemotherapy and radiotherapy, are widely applied in oncology practice. Their therapeutic success is little, and therefore, the search for novel technologies is ongoing. Many efforts have focused recently on the development of safe and efficient cancer nanomedicines. Nanoparticles are among them. They are uniquewith their properties on a nanoscale and hold the potential to exploit intrinsic metabolic differences between cancer and healthy cells. This feature allows them to induce high levels of toxicity in cancer cells with little damage to the surrounding healthy tissues. Graphene oxide is a promising 2D material found to play an important role in cancer treatments through several strategies: direct killing and chemosensitization, drug and gene delivery, and phototherapy. Several new treatment approaches based on nanoparticles, particularly graphene oxide, are currently under research in clinical trials, and some have already been approved. Here, we provide an update on the recent advances in nanomaterials-based CRC-targeted therapy, with special attention to graphene oxide nanomaterials. We summarise the epidemiology, carcinogenesis, stages of the CRCs, and current nanomaterials-based therapeutic approaches for its treatment.

Bioactivity of PEGylated Graphene Oxide Nanoparticles Combined with Near-Infrared Laser Irradiation Studied in Colorectal Carcinoma Cells.

Central focus in modern anticancer nanosystems is given to certain types of nanomaterials such as graphene oxide (GO). Its functionalization with polyethylene glycol (PEG) demonstrates high delivery efficiency and controllable release of proteins, bioimaging agents, chemotherapeutics and anticancer drugs. GO-PEG has a good biological safety profile, exhibits high NIR absorbance and capacity in photothermal treatment. To investigate the bioactivity of PEGylated GO NPs in combination with NIR irradiation on colorectal cancer cells we conducted experiments that aim to reveal the molecular mechanisms of action of this nanocarrier, combined with near-infrared light (NIR) on the high invasive Colon26 and the low invasive HT29 colon cancer cell lines. During reaching cancer cells the phototoxicity of GO-PEG is modulated by NIR laser irradiation. We observed that PEGylation of GO nanoparticles has well-pronounced biocompatibility toward colorectal carcinoma cells, besides their different malignant potential and treatment times. This biocompatibility is potentiated when GO-PEG treatment is combined with NIR irradiation, especially for cells cultured and treated for 24 h. The tested bioactivity of GO-PEG in combination with NIR irradiation induced little to no damages in DNA and did not influence the mitochondrial activity. Our findings demonstrate the potential of GO-PEG-based photoactivity as a nanosystem for colorectal cancer treatment.

Impact of Polyethylene Glycol Functionalization of Graphene Oxide on Anticoagulation and Haemolytic Properties of Human Blood.

Graphene oxide (GO) is one of the most explored nanomaterials in recent years. It has numerous biomedical applications as a nanomaterial including drug and gene delivery, contrast imaging, cancer treatment, etc. Since most of these applications need intravenous administration of graphene oxide and derivatives, the evaluation of their haemocompatibility is an essential preliminary step for any of the developed GO applications. Plentiful data show that functionalization of graphene oxide nanoparticles with polyethylene glycol (PEG) increases biocompatibility, thus allowing PEGylated GO to elicit less dramatic blood cell responses than their pristine counterparts. Therefore, in this work, we PEGylated graphene oxide nanoparticles and evaluated the effects of their PEGylation on the structure and function of human blood components, especially on the morphology and the haemolytic potential of red blood cells (RBCs). Further, we studied the effect of PEGylation on some blood coagulation factors, including plasma fibrinogen as well as on the activated partial thromboplastin (aPTT), prothrombin time (PT) and platelet aggregation. Our findings provide important information on the mechanisms through which PEGylation increases GO compatibility with human blood cells. These data are crucial for the molecular design and biomedical applications of PEGylated graphene oxide nanomaterials in the future.

Changes in Chromatin Organization Eradicate Cellular Stress Resilience to UVA/B Light and Induce Premature Aging.

Complex interactions among DNA and nuclear proteins maintain genome organization and stability. The nuclear proteins, particularly the histones, organize, compact, and preserve the stability of DNA, but also allow its dynamic reorganization whenever the nuclear processes require access to it. Five histone classes exist and they are evolutionarily conserved among eukaryotes. The linker histones are the fifth class and over time, their role in chromatin has been neglected. Linker histones interact with DNA and the other histones and thus sustain genome stability and nuclear organization. Saccharomyces cerevisiae is a brilliant model for studying linker histones as the gene for it is a single-copy and is non-essential. We, therefore, created a linker histone-free yeast strain using a knockout of the relevant gene and traced the way cells age chronologically. Here we present our results demonstrating that the altered chromatin dynamics during the chronological lifespan of the yeast cells with a mutation in ARP4 (the actin-related protein 4) and without the gene HHO1 for the linker histone leads to strong alterations in the gene expression profiles of a subset of genes involved in DNA repair and autophagy. The obtained results further prove that the yeast mutants have reduced survival upon UVA/B irradiation possibly due to the accelerated decompaction of chromatin and impaired proliferation. Our hypothesis posits that the higher-order chromatin structure and the interactions among chromatin proteins are crucial for the maintenance of chromatin organization during chronological aging under optimal and UVA-B stress conditions.

PEGylated Nanographene Oxide in Combination with Near-Infrared Laser Irradiation as a Smart Nanocarrier in Colon Cancer Targeted Therapy.

Anti-cancer therapies that integrate smart nanomaterials are the focus of cancer research in recent years. Here, we present our results with PEGylated nanographene oxide particles (nGO-PEG) and have studied their combined effect with near-infrared (NIR) irradiation on low and high invasive colorectal carcinoma cells. The aim is to develop nGO-PEG as a smart nanocarrier for colon cancer-targeted therapy. For this purpose, nGO-PEG nanoparticles' size, zeta potential, surface morphology, dispersion stability, aggregation, and sterility were determined and compared with pristine nGO nanoparticles (NPs). Our results show that PEGylation increased the particle sizes from 256.7 nm (pristine nGO) to 324.6 nm (nGO-PEG), the zeta potential from -32.9 to -21.6 mV, and wrinkled the surface of the nanosheets. Furthermore, nGO-PEG exhibited higher absorbance in the NIR region, as compared to unmodified nGO. PEGylated nGO demonstrated enhanced stability in aqueous solution, improved dispensability in the culture medium, containing 10% fetal bovine serum (FBS) and amended biocompatibility. A strong synergic effect of nGO-PEG activated with NIR irradiation for 5 min (1.5 W/cm-2 laser) was observed on cell growth inhibition of low invasive colon cancer cells (HT29) and their wound closure ability while the effect of NIR on cellular morphology was relatively weak. Our results show that PEGylation of nGO combined with NIR irradiation holds the potential for a biocompatible smart nanocarrier in colon cancer cells with enhanced physicochemical properties and higher biological compatibility. For that reason, further optimization of the irradiation process and detailed screening of nGO-PEG in combination with NIR and chemotherapeutics on the fate of the colon cancer cells is a prerequisite for highly efficient combined nanothermal and photothermal therapy for colon cancer.

Amination of Graphene Oxide Leads to Increased Cytotoxicity in Hepatocellular Carcinoma Cells.

Clinically, there is an urgent need to identify new therapeutic strategies for selectively treating cancer cells. One of the directions in this research is the development of biocompatible therapeutics that selectively target cancer cells. Here, we show that novel aminated graphene oxide (haGO-NH2) nanoparticles demonstrate increased toxicity towards human hepatocellular cancer cells compared to pristine graphene oxide(GO). The applied novel strategy for amination leads to a decrease in the size of haGO-NH2 and their zeta potential, thus, assuring easier penetration through the cell membrane. After characterization of the biological activities of pristine and aminated GO, we have demonstrated strong cytotoxicity of haGO-NH2 toward hepatic cancer cells - HepG2 cell line, in a dose-dependent manner. We have presented evidence that the cytotoxic effects of haGO-NH2 on hepatic cancer cells were due to cell membrane damage, mitochondrial dysfunction and increased reactive oxygen species (ROS) production. Intrinsically, our current study provides new rationale for exploiting aminated graphene oxide as an anticancer therapeutic.

Polydimethylsiloxane materials with supraphysiological elasticity enable differentiation of myogenic cells.

Myogenic differentiation during muscle regeneration is guided by various physical and biochemical factors. Recently, substratum elasticity has gained attention as a physical signal that influences both cell differentiation and tissue regeneration. In this work, we investigated the influence of substratum elasticity on proliferation and differentiation of myogenic cells, mouse myoblasts of the C2C12 cell line and mouse primary myoblasts derived from satellite cells-muscle stem cells playing key role in muscle regeneration. Materials with different elastic moduli within the MPa scale based on polydimethylsiloxane (PDMS) were used as cell substratum and characterized for surface roughness, wettability, and micromechanical characteristics. We found that surface properties of PDMS substrates are alter nonlinearly with the increase of the material's elastic modulus. Using this system we provide an evidence that materials with elastic modulus higher than that of physiological skeletal muscle tissue do not perturb myogenic differentiation of both types of myoblasts; thus, can be used as biomaterials for muscle tissue engineering. PDMS materials with elasticity within the range of 2.5-4 MPa may transiently limit the proliferation of myoblasts, but not the efficiency of their differentiation. Direct correlation between substratum elasticity and myogenic differentiation efficiency was not observed but the other surface properties of the PDMS materials such as nanoroughness and wettability were also diverse.

Aminated Graphene Oxide as a Potential New Therapy for Colorectal Cancer.

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.

Identification of signaling cascade in the insulin signaling pathway in response to nanopolystyrene particles.

The molecular response of animals to nanoplastic particles is still largely unclear. In this study, we employed a modified prolonged exposure system to investigate the molecular response of Caenorhabditis elegans to nanopolystyrene particles. Exposure to nanopolystyrene particles (1 µg/L) significantly decreased expressions of daf-2 encoding an insulin receptor, age-1 encoding a PI3K, and akt-1 encoding an Akt/PKB, and increased expression of daf-16 encoding a FOXO transcriptional factor in insulin signaling pathway. Among these genes, mutation of daf-2, age-1, or akt-1 induced a resistance to toxicity of nanopolystyrene particles, whereas mutation of daf-16 induced a susceptibility to the toxicity of nanopolystyrene particles. RNAi knockdown of daf-16 could further suppress the resistance of daf-2, age-1, or akt-1 mutant to the toxicity of nanopolystyrene particles. The insulin signaling pathway acted in intestinal cells to regulate the toxicity of nanopolystyrene particles. Moreover, sod-3 encoding a manganese superoxide dismutase, mtl-1 encoding a metallothionein, and gpd-2 encoding a glyceraldehyde-3-phosphate dehydrogenase were identified as downstream targeted genes for daf-16 in the regulation of toxicity of nanopolystyrene particles. Therefore, a signaling cascade of DAF-2-AGE-1-AKT-1-DAF-16-SOD-3/MTL-1/GPD-2 was identified in response to nanopolystyrene particles in nematodes. Additionally, this signaling cascade in the insulin signaling pathway may mediate a protective response for nematodes against the adverse effects from nanopolystyrene particles.

Dysregulation of let-7 by PEG modified graphene oxide in nematodes with deficit in epidermal barrier.

In nematode Caenorhabditis elegans, epidermal RNA interference (RNAi) knockdown of bli-1 encoding a cuticular collagen caused the toxicity induction of GO-PEG (PEG surface modified graphene oxide). In this study, we further found that epidermal RNAi knockdown of bli-1 increased expression of a microRNA let-7, and let-7 mutation suppressed the susceptibility of bli-1(RNAi) nematodes to GO-PEG toxicity. let-7 regulated the toxicity induction of GO-PEG by suppressing expression and function of its direct targets (HBL-1 and LIN-41). Like the nematodes with epidermal RNAi knockdown of bli-1, epidermal RNAi knockdown of hbl-1 or lin-41 also induced functional abnormality in epidermal barrier. Therefore, a signaling cascade of BLI-1-let-7-HBL-1/LIN-41 was raised to be involved in GO-PEG toxicity induction. Our data imply the dysregulation of let-7-mediated molecular machinery for developmental timing control by GO-PEG in nematodes with deficit in epidermal barrier caused by bli-1(RNAi).

Deficit in the epidermal barrier induces toxicity and translocation of PEG modified graphene oxide in nematodes.

The developmental basis for the epidermal barrier against the translocation of nanomaterials is still largely unclear in organisms. We here investigated the effect of deficits in the epidermal barrier on the translocation and toxicity of PEG modified graphene oxide (GO-PEG) in Caenorhabditis elegans. In wild-type or NR222 nematodes, GO-PEG exposure did not cause toxicity and affect the expression of epidermal-development related genes. However, GO-PEG exposure resulted in toxicity in mlt-7(RNAi) nematodes with deficit in the function of epidermal barrier. Epidermal RNAi knockdown of mlt-7 allowed GO-PEG accumulation and translocation into targeted organs through the epidermal barrier. Epidermal-development related proteins of BLI-1 and IFB-1 were identified as targets for MLT-7 in the regulation of GO-PEG toxicity and accounted for MLT-7 function in maintaining the epidermal barrier. AAK-2, a catalytic α subunit of AMP-activated protein kinase, was identified as another target for MLT-7 in the regulation of GO-PEG toxicity. AAK-2 functioned synergistically with BLI-1 or IFB-1 in the regulation of GO-PEG toxicity. Our data provide the molecular basis for the role of epidermal barrier against the toxicity and translocation of nanomaterials in organisms.

Developmental basis for intestinal barrier against the toxicity of graphene oxide.

BACKGROUND: Intestinal barrier is crucial for animals against translocation of engineered nanomaterials (ENMs) into secondary targeted organs. However, the molecular mechanisms for the role of intestinal barrier against ENMs toxicity are still largely unclear. The intestine of Caenorhabditis elegans is a powerful in vivo experimental system for the study on intestinal function. In this study, we investigated the molecular basis for intestinal barrier against toxicity and translocation of graphene oxide (GO) using C. elegans as a model animal. RESULTS: Based on the genetic screen of genes required for the control of intestinal development at different aspects using intestine-specific RNA interference (RNAi) technique, we identified four genes (erm-1, pkc-3, hmp-2 and act-5) required for the function of intestinal barrier against GO toxicity. Under normal conditions, mutation of any of these genes altered the intestinal permeability. With the focus on PKC-3, an atypical protein kinase C, we identified an intestinal signaling cascade of PKC-3-SEC-8-WTS-1, which implies that PKC-3 might regulate intestinal permeability and GO toxicity by affecting the function of SEC-8-mediated exocyst complex and the role of WTS-1 in maintaining integrity of apical intestinal membrane. ISP-1 and SOD-3, two proteins required for the control of oxidative stress, were also identified as downstream targets for PKC-3, and functioned in parallel with WTS-1 in the regulation of GO toxicity. CONCLUSIONS: Using C. elegans as an in vivo assay system, we found that several developmental genes required for the control of intestinal development regulated both the intestinal permeability and the GO toxicity. With the focus on PKC-3, we raised two intestinal signaling cascades, PKC-3-SEC-8-WTS-1 and PKC-3-ISP-1/SOD-3. Our results will strengthen our understanding the molecular basis for developmental machinery of intestinal barrier against GO toxicity and translocation in animals.

Identification of interneurons required for the aversive response of Caenorhabditis elegans to graphene oxide.

BACKGROUND: So far, how the animals evade the environmental nanomaterials is still largely unclear. In this study, we employed in vivo assay system of Caenorhabditis elegans to investigate the aversive behavior of nematodes to graphene oxide (GO) and the underlying neuronal basis. RESULTS: In this assay model, we detected the significant aversive behavior of nematodes to GO at concentrations more than 50 mg/L. Loss-of-function mutation of nlg-1 encoding a neuroligin with the function in connecting pre- and post-synaptic neurons suppressed the aversive behavior of nematodes to GO. Moreover, based on the neuron-specific activity assay, we found that the NLG-1 activity in AIY or AIB interneurons was required for the regulation of aversive behavior to GO. The neuron-specific activities of NLG-1 in AIY or AIB interneurons were also required for the regulation of GO toxicity. CONCLUSIONS: Using nlg-1 mutant as a genetic tool, we identified the AIY and AIB interneurons required for the regulation of aversive behavior to GO. Our results provide an important neuronal basis for the aversive response of animals to environmental nanomaterials.

Increased elastic modulus of plasma polymer coatings reinforced with detonation nanodiamond particles improves osteogenic differentiation of mesenchymal stem cells.

In the present study we demonstrated that composite PPHMDS/DND coatings with elastic moduli close to those of mature bone tissue (0.2-2.8 GPa) stimulated growth and osteogenic differentiation of human adipose-derived mesenchymal stem cells (hADMSCs). Composite coatings were prepared by a method of plasma polymerization (PP) where detonation nanodiamond (DND) particles in different amounts (0.1, 0.5, and 1 mg/mL) were added to hexamethyldisiloxane (HMDS) before plasma deposition. This method allows variation only in the reduced elastic modulus (Er´) with increase in the particle concentration, while the other surface properties, including surface wettability and topography, did not change. The response of hAD-MSCs to the increasing stifness showed an effect on adhesion and osteogenic differentiation but not on cell proliferation. Matrix mineralization and cell spreading were maximized on PPHMDS/DND coatings with the highest elastic modulus (2.826 GPa), while the differences in proliferation rates among the samples were negligible. In general, PPHMDS/DND coatings provide better conditions for growth and osteogenic differentiation of hAD-MSCs in comparison to glass coverslips, confirming their suitability for osteo-integration applications. Additionally, our findings support the hypothesis that biomaterials with elasticity similar to that of the native tissue can improve the differentiation potential of mesenchymal stem cells.

Osteogenic differentiation of mesenchymal stem cells using hybrid nanofibers with different configurations and dimensionality.

Novel, hybrid fibrinogen/polylactic acid (FBG/PLA) nanofibers with different configuration (random vs aligned) and dimensionality (2-D vs 3-D environment) were used to control the overall behavior and the osteogenic differentiation of human adipose-derived mesenchymal stem cells (ADMSCs). Aligned nanofibers in both the 2-D and 3-D configurations are proved to be favored for osteodifferentiation. Morphologically, we found that on randomly configured nanofibers, the cells developed a stellate-like morphology with multiple projections; however, time-lapse analysis showed significantly diminished cell movements. Conversely, an elongated cell shape with advanced cell spreading and extended actin cytoskeleton accompanied with significantly increased cell mobility were observed when cells attached on aligned nanofibers. Moreover, a clear tendency for higher alkaline phosphatase activity was also found on aligned fibers when ADMSCs were switched to osteogenic induction medium. The strongest accumulation of Alizarin red (AR) and von Kossa stain at 21 days of culture in osteogenic medium were found on 3-D aligned constructs while the rest showed lower and rather undistinguishable activity. Quantitative reverse transcription-polymerase chain reaction analysis for Osteopontin (OSP) and RUNX 2 generally confirmed this trend showing favorable expression of osteogenic genes activity in 3-D environment particularly in aligned configuration. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2065-2074, 2017.

Comparative study of cytotoxicity of detonation nanodiamond particles with an osteosarcoma cell line and primary mesenchymal stem cells.

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.

Multilayer coatings on biomaterials for control of MG-63 osteoblast adhesion and growth.

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.