Azo modified hyaluronic acid based nanocapsules: CD44 targeted, UV-responsive decomposition and drug release in liver cancer cells.

Herein, we demonstrate a novel UV-induced decomposable nanocapsule of natural polysaccharide (HA-azo/PDADMAC). The nanocapsules are fabricated based on layer-by-layer co-assembly of anionic azobenzene functionalized hyaluronic acid (HA-azo) and cationic poly diallyl dimethylammonium chloride (PDADMAC). When the nanocapsules are exposed to 365 nm light, ultraviolet photons can trigger the photo-isomerization of azobenzene groups in the framework. The nanocapsules could decompose from large-sized nanocapsules to small fragments. Due to their optimized original size (~180 nm), the nanocapsules can effectively avoid biological barriers, provide a long blood circulation and achieve high tumor accumulation. It can fast eliminate nanocapsules from tumor and release the loaded drugs for chemotherapy after UV-induced dissociation. Besides, HA is an endogenous polysaccharide that shows intrinsic targetability to CD44 receptors on surface of cancer cells. The intracellular experiment shows that the HA-azo/PDADMAC nanocapsules with CD44 targeting ability and UV-controlled intracellular drug release are promising for cancer chemotherapy.

Plastic pellets trigger feeding responses in sea anemones.

Multiple mechanisms for plastic consumption by marine animals have been proposed based on the feeding cues and behavior of the animal studied. We investigated plastic consumption in sea anemones. We found that anemones readily consumed pristine National Institute of Standards and Technology low-density polyethylene and high-density polyethylene II and III pre-production pellets. Anemone weight, crown area, and number of tentacles were measured before and after 12 days of daily pellet consumption. Crown area significantly increased for control anemones only. Fresh anemones were then sequentially fed consumed and egested pellets from two of the earlier daily trials to measure feeding retention time, which decreased over three to four feedings. The concentrations of elements in anemones (zinc, iron, arsenic, manganese, chromium, copper, vanadium, selenium, nickel, cadmium, and cobalt) were similar to control anemones that were not exposed to pellets. Lead concentrations were significantly higher in anemones fed HDPE III pellets as compared to control. Plastic consumption by marine animals might be reduced by reducing the amount of plastic that enters the ocean and understanding the chemical triggers underlying plastic consumption.

Intranasal delivery system of bacterial antigen using thermosensitive hydrogels based on a Pluronic-Gantrez conjugate.

Thermosensitive hydrogels have been studied as feasible needle-avoidance alternative to vaccine delivery. In this work, we report the development of a new thermal-sensitive hydrogel for intranasal vaccine delivery. This delivery system was formulated with a combination of the polymer Gantrez® AN119 and the surfactant Pluronic® F127 (PF127), with a high biocompatibility, biodegradability and immunoadjuvant properties. Shigella flexneri outer membrane vesicles were used as the antigen model. A stable and easy-to-produce thermosensitive hydrogel which allowed the incorporation of the OMV-antigenic complex was successfully synthetized. A rapid gel formation was achieved at body temperature, which prolonged the OMV-antigens residence time in the nasal cavity of BALB/c mice when compared to intranasal delivery of free-OMVs. In addition, the bacterial antigens showed a fast release profile from the hydrogel in vitro, with a peak at 30 min of incubation at 37 °C. Hydrogels appeared to be non-cytotoxic in the human epithelial HeLa cell line and nose epithelium as well, as indicated by the absence of histopathological features. Immunohistochemical studies revealed that after intranasal administration the OMVs reached the nasal associated lymphoid tissue. These results support the use of here described thermosensitive hydrogels as a potential platform for intranasal vaccination.

In- vitro evaluation of the bioactivity and the biocompatibility of a novel coated UHMWPE biomaterial for biomedical applications.

Ultra-High Molecular Weight Polyethylene (UHMWPE) is the gold standard biomaterial used as a bearing surface in total joint replacement surgeries. However, osteolysis and subsequent implant failure as a result of the production of wear debris may occur at the contacting surfaces. One potential solution to overcome this problem is to strengthen the surface of UHMWPE which can be achieved by adding a thin coating layer made of Polyamide. In this article, a combination of biological and biochemical tests, including cell viability, antibacterial activity (using Escherichia coli and Staphylococcus aureus), and wound healing assays were performed to assess the bioactivity and the biocompatibility of the coated specimens. Additional tests, such as simulated body fluid absorption, Alizarin Red Staining, Scanning Electron Microscopy, Energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy techniques were conducted to evaluate the moisture uptake, osteogenic activity, and the morphology of the coated samples. The antibacterial activity test results after 24 h incubation showed that the nylon-coated UHMWPE has significantly higher antibacterial activity compared to the uncoated UHMWPE. The results of wound closure showed that nylon-coated UHMWPE promotes more wound healing compared to the uncoated material that exhibits a similar percentage of wound closure as the control. This is the first study to demonstrate the superiority of the proposed coated biomaterial for wound healing applications with improved antibacterial capabilities.

Evaluation of biological and cytocompatible properties in nano silver-clay based polyethylene nanocomposites.

Nano-toxicological evaluation of a biomaterial is of primordial importance for application in therapeutics. This is one of first reports on systematic analysis of in vitro and in vivo cytocompatible properties of an antimicrobial polyethylene/silver-clay hybrid nanocomposite. The polymeric nanocomposite has been prepared using melt compounding route by a twin screw extruder with silver-clay hybrid content varying from 1 to 5 wt%. The morphology of the polyethylene/silver-clay nanocomposites was investigated using a combination of TEM and XRD techniques. The antimicrobial studies suggest strong biocidal action against E. coli, S. aureus and A. niger. In vitro cytocompatibility studies show excellent compatibility with human erythrocytes and dermal fibroblast cell lines, as compared to powder form silver-clay hybrids which demonstrated mild toxicity. Histopathological analysis of skin tissues excised from rats surgically stitched with nanocomposite film show no morphological change following 21 days of exposure. The developed nanocomposites show excellent antimicrobial activity coupled with cytocompatibility and are hence potential candidates for biomedical applications.

Macrophage inhibits the osteogenesis of fibroblasts in ultrahigh molecular weight polyethylene (UHMWPE) wear particle-induced osteolysis.

BACKGROUND: In the ultrahigh molecular weight polyethylene (UHMWPE) prosthetic environment, fibroblasts affected by wear particles have the capacity of osteogenesis to reduce osteolysis. We aimed to assess the effects of macrophages on the osteogenic capability of fibroblasts treated with UHMWPE wear particles. METHODS: The effect of different concentrations of UHMWPE (0, 0.01, 0.1, and 1 mg/ml, respectively) on macrophage proliferation were validated by MTT assay to determine the optimum one. The fibroblasts viability was further determined in the co-culture system of UHMWPE particles and macrophage supernatants. The experiment was designed as seven groups: (A) fibroblasts only; (B) fibroblasts + 1 mg/ml UHMWPE particles; and (C1-C5) fibroblasts + 1/16, 1/8, 1/4, 1/2, and 1/1 supernatants of macrophage cultures stimulated by 1 mg/ml UHMWPE particles vs. fibroblast complete media, respectively. Alizarin red staining was used to detect calcium accumulation. The expression levels of osteogenic proteins were detected by Western blot and ELISA, including alkaline phosphatase (ALP) and osteocalcin (OCN). RESULTS: The concentration of 0.1 mg/ml was considered as the optimum concentration for macrophage proliferation due to the survival rate and was highest among the four concentrations. Fibroblast viability was better in the group of fibroblasts + 1/16 ratio of macrophage supernatants stimulated by 1 mg/ml of UHMWPE particles than the other groups (1:8, 1:4, 1:2, 1:1). ALP and OCN expressions were significantly decreased in the group of fibroblasts + 1/4, 1/2, and 1/1 supernatants stimulated by 1 mg/ml of UHMWPE particles compared with other groups (1/8, 1/16) and the group of fibroblasts + 1 mg/ml UHMWPE (p < 0.5). CONCLUSIONS: Macrophages are potentially involved in the periprosthetic osteolysis by reducing the osteogenic capability of fibroblasts treated with wear particles generated from UHMWPE materials in total hip arthroplasty.

Design of PEI-conjugated bio-reducible polymer for efficient gene delivery.

The poly(cystaminebis(acrylamide)-diaminohexane) (poly(CBA-DAH)) was designed previously as a bio-reducible efficient gene delivery carrier. However, the high weight ratio required to form the polyplexes between poly(CBA-DAH) with pDNA is still a problem that needs to be addressed. To solve this problem and increase the transfection efficiency, poly(ethylenimine) (PEI, 1.8 kDa) was conjugated to poly(CBA-DAH) via disulfide bond. The PEI conjugated poly(CBA-DAH) (PCDP) can bind with pDNA at a very low weight ratio of 0.5 and above, like PEI 25 kDa, and form the polyplexes with nano-size (102-128 nm) and positive surface charge (27-34 mV). PCDP and PCDP polyplexes had negligible cytotoxicity and indicated similar or better cellular uptake than the comparison groups such as PEI 25 kDa and Lipofectamine® polyplexes. To confirm the transfection efficiency, the plasmid DNA (pDNA) encoded with the luciferase reporter gene (gWiz-Luc) and green fluorescent protein reporter gene (GFP) were used and treated with PCDP into the A549, Huh-7, and Mia PaCa-2 cells. PCDP/pDNA polyplexes showed highest transfection efficiency in all tested cell lines. In the luciferase assay, PCDP polyplexes showed 10.2 times higher gene transfection efficiency than Lipofectamine® polyplexes in mimic in vivo conditions (30% FBS, A549 cells). The VEGF siRNA expressing plasmid (pshVEGF), which is constructed as a therapeutic gene by our previous work, was delivered by PCDP into the cancer cells. The VEGF gene expression of PCDP/pshVEGF polyplexes was dramatically lower than control and the VEGF gene silencing efficiencies of PCDP/pshVEGF (w/w; 10/1) polyplexes were 54% (A549 cells), 77% (Huh-7 cells), and 66% (Mia PaCa-2 cells). In addition, PCDP/pshVEGF had reduced cell viability rates of about 31% (A549 cells), 39% (Huh-7 cells), and 42% (Mia PaCa-2 cells) and showed better results than all comparison groups. In the transfection efficiency and VEGF silencing assay, PCDP polyplexes showed better results than poly(CBA-DAH) at 4-fold lower weight ratio. The data of all experiments demonstrate that the synthesized PCDP could be used for efficient gene delivery and could be widely applied.

Study on biocompatibility, tribological property and wear debris characterization of ultra-low-wear polyethylene as artificial joint materials.

Ultra-low-wear polyethylene (ULWPE) is a new type polyethylene made by experts who are from China petrochemical research institute, which is easy to process and implant. Preliminary test showed it was more resistant to wear than that of Ultra-high-molecular weight polyethylene (UHMWPE). The purpose of the research is to study biocompatibility, bio-tribological properties and debris characterization of ULWPE. Cytotoxicity test, hemolysis test, acute/chronic toxicity and muscular implantation test were conducted according to national standard GB/T-16886/ISO-10993 for evaluation requirements of medical surgical implants. We obtained that this novel material had good biocompatibility and biological safety. The wear performance of ULWPE and UHMWPE was evaluated in a pin-on-disc (POD) wear tester within two million cycles and a knee wear simulator within six million cycles. We found that the ULWPE was higher abrasion resistance than the UHMWPE, the wear rate of ULWPE by POD test and knee wear simulator was 0.4 mg/106cycles and (16.9 ±â€¯1.8)mg/106cycles respectively, while that of UHMWPE was 1.8 mg/106cycles and (24.6 ±â€¯2.4)mg/106cycles. The morphology of wear debris is also an important factor to evaluate artificial joint materials, this study showed that the ULWPE wear debris gotten from the simulator had various different shapes, including spherical, block, tear, etc. The morphology of worn surface and wear debris analysis showed that wear mechanisms of ULWPE were adhesion wear, abrasive wear and fatigue wear and other wear forms, which were consistent with that of UHMWPE. Thus we conclude that ULWPE is expected to be a lifetime implantation of artificial joint.

Cytotoxicity evaluation of unfunctionalized multiwall carbon nanotubes-ultrahigh molecular weight polyethylene nanocomposites.

The carbon nanotubes were chosen for this study since long, small to medium diameter, and unfunctionalized nanotubes are considered less favorable for nontoxic applications. The intent of the study is to expand the use of CNTs beyond current understood nontoxic means. Multiwall carbon nanotube/ultrahigh molecular weight polyethylene (MWCNT/UHMWPE) nanocomposites were prepared by reinforcing long chain UHMWPE with MWCNTs. These nanocomposites were prepared to study their cytotoxicity assessments with human fibroblast cell lines. Cell adhesion, proliferation, and differentiation were studied with human fibroblast cell lines. In vitro studies revealed good cell viability on the surface of MWCNT/UHMWPE composites even after 72 h. The nanocomposites showed better cell attachment for fibroblasts than pristine UHMWPE. Overall, the results showed that MWCNT/UHMWPE composites displayed good cellular growth and biocompatibility indicating another way CNTs can be nontoxic. These nanocomposites offer nontoxic conditions that can be used in biomedical devices because the long chain UHMWPE is entangled with long MWCNTs. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3042-3049, 2017.

Genotoxic evaluation of poly(anhydride) nanoparticles in the gastrointestinal tract of mice.

Gantrez® AN 119-based NPs have been developed as oral drug carriers due to their strong bioadhesive interaction with components of the gastrointestinal mucosa and to their adaptable surface. The use of mannosamine to coat Gantrez® AN 119-based NPs results in a high mucus-permeable carrier, able to reach the gastrointestinal epithelium. Although their efficacy to transport a therapeutic agent has been demonstrated, their safety has not yet been thoroughly studied. They have proved to be non-cytotoxic, non-genotoxic and non-mutagenic in vitro; however, the in vivo toxicity profile has not yet been determined. In this study, the in vivo genotoxic potential of Gantrez® AN 119 NPs coated with mannosamine (GN-MA-NP) has been assessed using the in vivo comet assay in combination with the enzyme formamidopyrimidine DNA glycosylase in mice, following the OECD test guideline 489. To determine the relevant organs to analyse and the sampling times, an in vivo biodistribution study was also carried out. Results showed a statistically significant induction of DNA strand breaks and oxidized bases in the duodenum of animals exposed to 2000 mg/kg bw. However, this effect was not observed at lower doses (i.e. 500 and 1000 mg/kg which are closer to the potential therapeutic doses) or in other organs. In conclusion, GN-MA-NP are promising nanocarriers as oral drug delivery systems.

Cardiovascular toxicity assessment of poly (ethylene imine)- based cationic polymers on zebrafish model.

Poly(ethylene imine)s (PEIs) have gained enormous attention in designing novel drug delivery systems for cancer treatment. High molecular weight of PEIs such as PEI 25 kD are promising for their drug carrying capacity. However, increased molecular weight is associated with toxicity. Currently, the toxicity evaluation of PEIs is mainly focused on the culture cell models, with very few studies investigating the risk assessment in vivo. Herein, the systemic evaluation of branched PEI 25 kD and PEI-CyD (PC) composed of low molecular PEI (Mw 600) and ß-cyclodextrin (ß-CyD) is performed in zebrafish model and endothelial cells. Our finding indicate that exposure of PC and PEI 25 kD can induce high mortality rate, shorten hatching time, promote malformations and cell apoptosis of zebrafish embryos in a dose-dependent manner. Most significantly, the cationic polymer PC and PEI 25 kD can decrease heart rate of zebrafish embryos and down-regulate the expression of heart development-related genes, which demonstrate their cardiovasculature toxicity. In this case, we further investigate the effect of PC on endothelial cells. Indeed, PC can induce endothelial cells dysfunction, including oxidative stress and apoptosis which are involved in cardiovascular diseases. These fundamental studies provide valuable insights into the biocompatible evaluation of PEI based drug carriers.

Macrophage integrins modulate response to ultra-high molecular weight polyethylene particles and direct particle-induced osteolysis.

Aseptic loosening due to peri-prosthetic osteolysis is one of the primary causes for failure of artificial joint replacements. Implant-derived wear particles, often ultra-high molecular weight polyethylene (UHMWPE) microparticles, initiate an inflammatory cascade upon phagocytosis by macrophages, which leads to osteoclast recruitment and activation, ultimately resulting in osteolysis. Investigation into integrin receptors, involved in cellular interactions with biomaterial-adsorbed adhesive proteins, is of interest to understand and modulate inflammatory processes. In this work, we investigate the role of macrophage integrins Mac-1 and RGD-binding integrins in response to UHMWPE wear particles. Using integrin knockout mice as well as integrin blocking techniques, reduction in macrophage phagocytosis and inflammatory cytokine secretion is demonstrated when these receptors are either absent or blocked. Along this line, various opsonizing proteins are shown to differentially modulate microparticle uptake and macrophage secretion of inflammatory cytokines. Furthermore, using a calvarial osteolysis model it is demonstrated that both Mac-1 integrin and RGD-binding integrins modulate the particle induced osteolysis response to UHMWPE microparticles, with a 40% decrease in the area of osteolysis by the absence or blocking of these integrins, in vivo. Altogether, these findings indicate Mac-1 and RGD-binding integrins are involved in macrophage-directed inflammatory responses to UHMWPE and may serve as therapeutic targets to mitigate wear particle induced peri-prosthetic osteolysis for improved performance of implanted joints.

Evaluation of the cytotoxicity, genotoxicity and mucus permeation capacity of several surface modified poly(anhydride) nanoparticles designed for oral drug delivery.

The main concerns with drugs designed for oral administration are their inactivation or degradation in the harsh conditions of the gastrointestinal tract, their poor solubility through the gastrointestinal mucus gel layer, the poor intestinal epithelium permeability that limits their absorption, and their toxicity. In this context, poly(anhydride) nanoparticles are capable of protecting the drug from the harsh environment, reduce the drug's toxicity and, by virtue of surface modification, to enhance or reduce their mucus permeability and the bioadhesion to specific target cells. The copolymer between methyl vinyl ether and maleic anhydride (commercialized as Gantrez® AN 119) are part of the poly(anhydride) nanoparticles. These biocompatible and biodegradable nanoparticles (NPs) can be modified by using different ligands. Their usefulness as drug carriers and their bioadhesion with components of the intestinal mucosa have been described. However, their toxicity, genotoxicity and mucus permeation capacity has not been thoroughly studied. The aim of this work was to evaluate and compare the in vitro toxicity, cell viability and in vitro genotoxicity of the bioadhesive empty Gantrez® AN 119 NPs modified with dextran, aminodextran, 2-hydroxypropyl-ß-cyclodextrin, mannosamine and poly-ethylene glycol of different molecular weights. Results showed that, in general, coated NPs exhibit better mucus permeability than the bare ones, those coated with mannosamine being the most permeable ones. The NPs studied did not affect cell metabolism, membrane integrity or viability of Caco-2 cells at the different conditions tested. Moreover, they did not induce a relevant level of DNA strand breaks and FPG-sensitive sites (as detected with the comet assay).

Antitumor activity and systemic effects of PVM/MA-shelled selol nanocapsules in lung adenocarcinoma-bearing mice.

Selol is a semi-synthetic compound containing selenite that is effective against cancerous cells and safer for clinical applications in comparison with other inorganic forms of selenite. Recently, we have developed a formulation of poly(methyl vinyl ether-co-maleic anhydride)-shelled selol nanocapsules (SPN), which reduced the proliferative activity of lung adenocarcinoma cells and presented little deleterious effects on normal cells in in vitro studies. In this study, we report on the antitumor activity and systemic effects induced by this formulation in chemically induced lung adenocarcinoma-bearing mice. The in vivo antitumor activity of the SPN was verified by macroscopic quantification, immunohistochemistry and morphological analyses. Toxicity analyses were performed by evaluations of the kidney, liver, and spleen; analyses of hemogram and plasma levels of alanine aminotransferase, aspartate transaminase, urea, and creatinine; and DNA fragmentation and cell cycle activity of the bone marrow cells. Furthermore, we investigated the potential of the SPN formulation to cause hemolysis, activate the complement system, provoke an inflammatory response and change the conformation of the plasma proteins. Our results showed that the SPN reduced the area of the surface tumor nodules but not the total number of tumor nodules. The biochemical and hematological findings were suggestive of the low systemic toxicity of the SPN formulation. The surface properties of the selol nanocapsules point to characteristics that are consistent with the treatment of the tumors in vivo: low hemolytic activity, weak inflammatory reaction with no activation of the complement system, and mild or absent conformational changes of the plasma proteins. In conclusion, this report suggests that the SPN formulation investigated herein exhibits anti-tumoral effects against lung adenocarcinoma in vivo and is associated with low systemic toxicity and high biocompatibility.

The mining chemical Polydadmac is cytotoxic but does not interfere with Cu-induced toxicity in Atlantic salmon hepatocytes.

To speed up sedimentation of suspended solids the mining industry often uses flocculent chemicals. In this work we evaluated the cytotoxic and mechanistic effects of Polydadmac, and its basic component Dadmac, on fish cells. Dose-response effects, temperature-dependent effects and impact of Dadmac and Polydadmac on Cu toxicity were studied in Atlantic salmon hepatocytes. We used the xCELLigence system and the MTT test for cytotoxicity assessments, and real-time RT-qPCR to evaluate molecular effects. The results showed a cytotoxic response for Polydadmac but not for Dadmac. Elevated levels of Cu were cytotoxic. Moderately cytotoxic concentrations of Cu (100-1000 µM) induced significant responses on the transcription of a number of genes in the cells, i.e. cuznsod (sod1), cat, mnsod (sod2), nfe2l2, hmox1, mta, casp3b, casp6, bclx, cyp1a, ccs, atp7a, app, mmp13, esr1, ppara, fads2 and ptgs2. A factorial PLS regression model for mnsod transcription showed a synergistic effect between Dadmac and Cu exposure in the cells, indicating an interaction effect between Dadmac and Cu on mitochondrial ROS scavenging. No interaction effects were seen for Polydadmac on Cu toxicity. In conclusion, Polydadmac is cytotoxic at elevated concentrations but appears to have low ability to interfere with Cu toxicity in Atlantic salmon liver cells.

The biological response to nanometre-sized polymer particles.

Recently, nanometre-sized UHMWPE particles generated from hip and knee replacements have been identified in vitro and in vivo. UHMWPE particles in the 0.1-1.0µm size range have been shown to be more biologically active than larger particles, provoking an inflammatory response implicated in late aseptic loosening of total joint replacements. The biological activity of nanometre-sized particles has not previously been studied. The biological response to clinically-relevant UHMWPE wear particles including nanometre-sized and micrometre-sized, along with polystyrene particles (FluoSpheres 20nm, 60nm, 200nm and 1.0µm), and nanometre-sized model polyethylene particles (Ceridust 3615®), was determined in terms of osteolytic cytokine release from primary human peripheral blood mononuclear cells (PBMNCs). Nanometre-sized UHMWPE wear particles, nanometre-sized Ceridust 3615® and 20nm FluoSpheres had no significant effect on TNF-α, IL-1ß, IL-6 and IL-8 release from PBMNCs at a concentration of 100µm(3) particles per cell after 12 and 24h. The micrometre-size UHMWPE wear particles (0.1-1.0µm) and 60nm, 200nm and 1.0µm FluoSpheres caused significantly elevated osteolytic cytokine release from PBMNCs. These results indicated that particles below circa 50nm fail to activate PBMNCs and that particle size, composition and morphology played a crucial role in cytokine release by particle stimulated macrophages.

Cytotoxicity of four denture adhesives on human gingival fibroblast cells.

OBJECTIVE: The purpose of this study was to compare the cytotoxicity of four denture adhesives on human gingival fibroblast cells. MATERIALS AND METHODS: Immortalized human gingival fibroblasts were cultured with one of four different denture adhesives, Polident, Protefix, Staydent or Denfix-A, which was placed in insert dishes (10% w/v concentration) for 48 h. The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay and flow cytometric apoptosis assay were used to evaluate cell viability and apoptosis rates. The fibroblasts were also examined under a scanning electron microscope. RESULTS: The MTT assay showed that all denture adhesives resulted in a significantly lower cell viability compared to the control cells propagated in normal culture medium (p < 0.05), with Staydent demonstrating the lowest cell viability. According to the flow cytometric apoptosis assay, Staydent and Protefix showed significantly higher apoptosis rates than the control group (p < 0.05), whereas Polident and Denfix-A did not demonstrate any significant differences (p > 0.05). Staydent showed the highest apoptosis rate. Scanning electron microscopy showed that the cells of the Staydent group underwent cytoplasmic membrane shrinkage, with cell free areas containing residual fragments of the membrane of dead cells. CONCLUSIONS: The four denture adhesives evaluated in this study imparted cytotoxic effects on human gingival fibroblast cells. Staydent showed the highest toxicity.

Novel composite plastics containing silver(I) acylpyrazolonato additives display potent antimicrobial activity by contact.

New silver(I) acylpyrazolonato derivatives displaying a mononuclear, polynuclear, or ionic nature, as a function of the ancillary azole ligands used in the synthesis, have been fully characterized by thermal analysis, solution NMR spectroscopy, solid-state IR and NMR spectroscopies, and X-ray diffraction techniques. These derivatives have been embedded in polyethylene (PE) matrix, and the antimicrobial activity of the composite materials has been tested against three bacterial strains (E. coli, P. aeruginosa, and S. aureus): Most of the composites show antimicrobial action comparable to PE embedded with AgNO3 . Tests by contact and release tests for specific migration of silver from PE composites clearly indicate that, at least in the case of the PE, for composites containing polynuclear silver(I) additives, the antimicrobial action is exerted by contact, without release of silver ions. Moreover, PE composites can be re-used several times, displaying the same antimicrobial activity. Membrane permeabilization studies and induced reactive oxygen species (ROS) generation tests confirm the disorganization of bacterial cell membranes. The cytotoxic effect, evaluated in CD34(+) cells by MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazoliumbromide) and CFU (colony forming units) assays, indicates that the PE composites do not induce cytotoxicity in human cells. Studies of ecotoxicity, based on the test of Daphnia magna, confirm tolerability of the PE composites by higher organisms and exclude the release of Ag(+) ions in sufficient amounts to affect water environment.

NaCS-PDMDAAC immobilized cultivation of recombinant Dictyostelium discoideum for soluble human Fas ligand production.

Dictyostelium discoideum is a promising eukaryotic host for the expression of heterologous proteins requiring post-translational modifications. However, the dilute nature of D. discoideum cell culture limits applications for high value proteins production. D. discoideum cells, entrapped in sodium cellulose sulfate/poly-dimethyl-diallyl-ammonium chloride (NaCS-PDMDAAC) capsules were used for biosynthesis of the heterologous protein, soluble human Fas ligand (hFasL). Semi-continuous cultivations with capsules recycling were carried out in shake flasks. Also, a scaled-up cultivation of immobilized D. discoideum for hFasL production in a customized vitreous airlift bioreactor was conducted. The results show that NaCS-PDMDAAC capsules have desirable biophysical properties including biocompatibility with the D. discoideum cells and good mechanical stability throughout the duration of cultivation. A maximum cell density of 2.02 × 10(7) cells mL(-1) (equivalent to a maximum cell density of 2.22 × 10(8) cells mL(-1) in capsules) and a hFasL concentration of 130.40 µg L(-1) (equivalent to a hFasL concentration of 1434.40 µg L(-1) in capsules) were obtained in shake flask cultivation with capsules recycling. Also, a maximum cell density of 1.72 × 10(7) cells mL(-1) (equivalent to a maximum cell density of 1.89 × 10(8) cells mL(-1) in capsules) and a hFasL concentration of 106.10 µg L(-1) (equivalent to a hFasL concentration of 1167.10 µg L(-1) in capsules) were obtained after ∼170 h cultivation in the airlift bioreactor (with a working volume of 200 mL in a 315 mL bioreactor). As the article presents a premier work in the application of NaCS-PDMDAAC immobilized D. discoideum cells for the production of hFasL, more work is required to further optimize the system to generate higher cell densities and hFasL titers for large-scale applications.

Cytotoxic effects of denture adhesives on primary human oral keratinocytes, fibroblasts and permanent L929 cell lines.

BACKGROUND: To date, there have been very little data on the cytotoxic responses of different cell lines to denture adhesives. OBJECTIVE: To determine the cytotoxicity of three denture adhesives on primary human oral keratinocytes (HOKs), fibroblasts (HOFs) and permanent mouse fibroblasts cell lines (L929). METHODS: Three commercial denture adhesives (two creams and one powder) were prepared for indirect contact using the agar diffusion test, as well as extracts in MTT assay. The results of the MTT assay were statistically analysed by one-way anova and Tukey's test (p < 0.05). RESULTS: All of the tested denture adhesives showed mild to moderate cytotoxicity to primary HOKs (p < 0.001), whereas none of three was toxic to L929 cells (p > 0.05) in both assays. For primary HOFs cultures, slight cytotoxicity was observed for one of the products from the agar diffusion test and undiluted eluates of all tested adhesives with MTT assay (p < 0.01). CONCLUSION: Denture adhesives are toxic to the primary HOKs and HOFs cultures, whereas non-toxic to L929 cells. The results suggest that primary human oral mucosal cells may provide more valuable information in toxicity screening of denture adhesives.