New Carbon-Mineral Sorbent Based on Aluminum Oxide, Polydimethylsiloxane, and Single-Wall Carbon Nanotubes: Assessment of the Effect on Erythrocytes In Vitro.

A comparative study of the effect of a sorbent with nanotubes (Al2O3@ WCNT-PDMS) and a carbon-mineral sorbent (Al2O3@C) on the parameters of human erythrocytes was carried out. Using scanning flow cytometry, the morphological and functional parameters of venous blood erythrocytes as well as drainage blood after its perfusion through columns with sorbents were determined. The compared samples Al2O3@SWCNT-PDMS and Al2O3@C are similar by their effect on the morphological and functional parameters of erythrocytes. The maximum membrane extensibility increased to a greatest extent after contact with Al2O3@C, the amount of hemoglobin in erythrocytes decreased to the greatest extent after perfusion through a column with Al2O3@SWCNT-PDMS sorbent. The scanning flow cytometry is promising for assessing the effect on erythrocytes of new sorption materials intended for blood detoxification. Changes in the parameters of erythrocytes of blood collected in a sterile drainage system for subsequent reinfusion were revealed.

Biomimicry of oil infused layer on 3D printed poly(dimethylsiloxane): Non-fouling, antibacterial and promoting infected wound healing.

The nepenthes-inspired slippery liquid-infused surface has led to multiple potentials in biomedical devices' design. This study aims to develop a biomimetic, environmentally-friendly slippery layer of oil-infused 3D printed polydimethylsiloxane with anti-bacterial nanosilver (iPDMS/AgNPs) for wound dressing. The engineered 3D printed iPDMS can cater the different requirements of wounds with antifouling, anti-blood staining, and kill bacteria. iPDMS/AgNPs not only exhibits biocompatibility, against adherence and effective antibacterial activity but also effectively promotes neo-epithelial and granulation tissue formation to accelerate wound healing in vivo. Optimized rheologic parameters were obtained for the 3D printable iPDMS pre-polymerization condition. Scanning electronic micrograph (SEM) and Energy Dispersive Spectrometer (EDS) show a uniform mesh with AgNPs dotted on the printed dressing. No cytotoxicity of iPDMS/AgNPs has been found via cell Counting Kit-8(CCK-8) assay. Meanwhile, the membranes infused with silicon oil effectively prevented from the adherence of the two standard drug-resistant bacteria, Staphylococcus aureus and Escherichia coli (PDMS vs. PDMS+oil, p < 0.05; PDMS+0.5%AgNPs vs. iPDMS+0.5%AgNPs, p < 0.05; PDMS+2.5%AgNPs vs. iPDMS+2.5%AgNPs, p < 0.05). By bacteria co-culture model iPDMS/AgNPs can kill about 80% of Staphylococcus aureus and Escherichia coli. When applied to a full-thickness wound defect model of murine, iPDMS/AgNPs was effective in anti-infection. It also promotes the epithelialization, the granulation tissue formation, and wound healing. These findings demonstrate that iPDMS/AgNPs may have therapeutic promise as an ideal wound dressing shortly.

Precision-porous templated scaffolds of varying pore size drive dendritic cell activation.

Scaffold based systems have shown significant potential in modulating immune responses in vivo. While there has been much attention on macrophage interactions with tissue engineered scaffolds for tissue regeneration, fewer studies have looked at the effects of scaffold design on the response of immune cells-that is, dendritic cells (DCs). Here, we present the effects of varying pore size of poly (2-hydroxyethyl methacrylate) (pHEMA) and poly(dimethylsiloxane) (PDMS, silicone) scaffolds on the maturation and in vivo enrichment of DCs. We employ a precision templating method to make 3-D porous polymer scaffolds with uniformly defined and adjustable architecture. Hydrophilic pHEMA and hydrophobic PDMS scaffolds were fabricated in three pore sizes (20, 40, 90 µm) to quantify scaffold pore size effects on DCs activation/maturation in vitro and in vivo. In vitro results showed that both pHEMA and PDMS scaffolds could promote maturation in the DC cell line, JAWSII, that resembled lipopolysaccharide (LPS)-activated/matured DCs (mDCs). Scaffolds with smaller pore sizes correlate with higher DC maturation, regardless of the polymer used. In vivo, when implanted subcutaneously in C57BL/6J mice, scaffolds with smaller pore sizes also demonstrated more DCs recruitment and more sustained activation. Without the use of DC chemo-attractants or chemical adjuvants, our results suggested that DC maturation and scaffold infiltration profile can be modulated by simply altering the pore size of the scaffolds.

Flammability testing of 22 conventional European pediculicides.

Lice have been parasitizing humans for at least 10,000 years. Since then, humans have tried to rid themselves of these unpleasant and potentially disease-carrying insects. Despite various plant extracts and chemical compounds being used to combat recurring infestations to this date, several lice populations have developed resistance to some of the abundantly used compounds. This resulted in the development of anti-louse products that physically kill the different lice stages. Today, a widely used group of delousing agents are dimethicones (polydimethylsiloxane PDMS) which function by suffocating the lice. However, many dimethicones and related products are highly flammable which makes them potentially dangerous for treatment. In the present study, we tested the flammability of 22 delousing agents in order to shed some light onto this currently unresolved problem in the product design of pediculicides. Thirteen products were easily ignitable, some even by distant contact with a sparkler.

Antibacterial and anticancer PDMS surface for mammalian cell growth using the Chinese herb extract paeonol(4-methoxy-2-hydroxyacetophenone).

Polydimethylsiloxane (PDMS) is widely used as a cell culture platform to produce micro- and nano-technology based microdevices. However, the native PDMS surface is not suitable for cell adhesion and is always subject to bacterial pollution and cancer cell invasion. Coating the PDMS surface with antibacterial or anticancer materials often causes considerable harm to the non-cancer mammalian cells on it. We have developed a method to fabricate a biocompatible PDMS surface which not only promotes non-cancer mammalian cell growth but also has antibacterial and anticancer activities, by coating the PDMS surface with a Chinese herb extract, paeonol. Coating changes the wettability and the elemental composition of the PDMS surface. Molecular dynamic simulation indicates that the absorption of paeonol onto the PDMS surface is an energy favourable process. The paeonol-coated PDMS surface exhibits good antibacterial activity against both Gram-positive and Gram-negative bacteria. Moreover considerable antibacterial activity is maintained after the coated surface is rinsed or incubated in water. The coated PDMS surface inhibits bacterial growth on the contact surface and promotes non-cancer mammalian cell growth with low cell toxicity; meanwhile the growth of cancer cells is significantly inhibited. Our study will potentially guide PDMS surface modification approaches to produce biomedical devices.

The Antioxidation Mechanism of Polydimethylsiloxane in Oil.

Strong and stable antioxidation effects of polydimethylsiloxane (PDMS) are widely accepted and utilized in commercial frying oil; however, the mechanism is not fully established. On the other hand, canola oil contains about 700 ppm (mg/kg-oil) of the natural antioxidant, tocopherol. Canola oil containing 0, 1 and 10 ppm added PDMS was heated at 180°C for 1 h under stirring, then left for 2-3 days at room temperature; this treatment was repeated 5 times. Compared to pure canola oil, PDMS-containing canola oil exhibited remarkably lower peroxide, p-anisidine and acid values, a lower decrease in tocopherol content but a higher oxygen content during the heating experiments, implicating low oxygen consumption for the oxidation. While PDMS has not been known to exhibit antioxidative effects at ambient temperatures, the present results show that PDMS prevents autoxidation as well as thermal oxidation. In addition, PDMS, not tocopherols, provided the major antioxidative effect during intermittent heating, and the decrease of tocopherols was significantly inhibited by PDMS. Phase contrast microscopy confirmed that PDMS contained in canola oil was suspended as particles. Also, the oxygen content in standing PDMS-containing canola oil decreased as the depth of oil increased, corresponding to the PDMS distribution, which also decreased as the depth of oil increased. Moreover, PDMS had a higher affinity for oxygen than canola oil in a mixture of canola oil/PDMS, 1:1 v/v. Thus, it is suggested that PDMS restricted the behavior of oxygen dissolved in canola oil by attracting oxygen in and around the PDMS particles, which is wholly different from the radical scavenging antioxidation of tocopherol.

The synergistic effect of micro-topography and biochemical culture environment to promote angiogenesis and osteogenic differentiation of human mesenchymal stem cells.

Critical failures associated with current engineered bone grafts involve insufficient induction of osteogenesis of the implanted cells and lack of vascular integration between graft scaffold and host tissue. This study investigated the combined effects of surface microtextures and biochemical supplements to achieve osteogenic differentiation of human mesenchymal stem cells (hMSCs) and revascularization of the implants in vivo. Cells were cultured on 10µm micropost-textured polydimethylsiloxane (PDMS) substrates in either proliferative basal medium (BM) or osteogenic medium (OM). In vitro data revealed that cells on microtextured substrates in OM had dense coverage of extracellular matrix, whereas cells in BM displayed more cell spreading and branching. Cells on microtextured substrates in OM demonstrated a higher gene expression of osteoblast-specific markers, namely collagen I, alkaline phosphatase, bone sialoprotein, and osteocalcin, accompanied by substantial amount of bone matrix formation and mineralization. To further investigate the osteogenic capacity, hMSCs on microtextured substrates under different biochemical stimuli were implanted into subcutaneous pockets on the dorsal aspect of immunocompromised mice to study capacity for ectopic bone formation. In vivo data revealed greater expression of osteoblast-specific markers coupled with increased vascular invasion on microtextured substrates with hMSCs cultured in OM. Together, these data represent a novel regenerative strategy that incorporates defined surface microtextures and biochemical stimuli to direct combined osteogenesis and re-vascularization of engineered bone scaffolds for musculoskeletal repair and relevant bone tissue engineering applications.

Preventing hypoxia-induced cell death in beta cells and islets via hydrolytically activated, oxygen-generating biomaterials.

A major hindrance in engineering tissues containing highly metabolically active cells is the insufficient oxygenation of these implants, which results in dying or dysfunctional cells in portions of the graft. The development of methods to increase oxygen availability within tissue-engineered implants, particularly during the early engraftment period, would serve to allay hypoxia-induced cell death. Herein, we designed and developed a hydrolytically activated oxygen-generating biomaterial in the form of polydimethylsiloxane (PDMS)-encapsulated solid calcium peroxide, PDMS-CaO(2). Encapsulation of solid peroxide within hydrophobic PDMS resulted in sustained oxygen generation, whereby a single disk generated oxygen for more than 6 wk at an average rate of 0.026 mM per day. The ability of this oxygen-generating material to support cell survival was evaluated using a ß cell line and pancreatic rat islets. The presence of a single PDMS-CaO(2) disk eliminated hypoxia-induced cell dysfunction and death for both cell types, resulting in metabolic function and glucose-dependent insulin secretion comparable to that in normoxic controls. A single PDMS-CaO(2) disk also sustained enhanced ß cell proliferation for more than 3 wk under hypoxic culture conditions. Incorporation of these materials within 3D constructs illustrated the benefits of these materials to prevent the development of detrimental oxygen gradients within large implants. Mathematical simulations permitted accurate prediction of oxygen gradients within 3D constructs and highlighted conditions under which supplementation of oxygen tension would serve to benefit cellular viability. Given the generality of this platform, the translation of these materials to other cell-based implants, as well as ischemic tissues in general, is envisioned.

In vitro analysis of the cytotoxicity and the antimicrobial effect of four endodontic sealers.

INTRODUCTION: The aim of this study was to investigate in vitro the cytotoxicity and antibacterial properties of four different endodontic sealers using human periodontal ligament fibroblast cell proliferation and visual analysis of growth inhibition. METHODS: A silicone (GuttaFlow), silicate (EndoSequence BC), zinc oxide eugenol (Pulp Canal Sealer EWT) and epoxy resin (AH Plus Jet) based sealer were incubated with PDL fibroblasts (104 cells/ml, n=6) up to 96 h. Cell proliferation (RFU) was determined by means of the Alamar Blue assay. Cell growth and morphology was visualized by means of fluorescent dyes. Possible antibacterial properties of the different sealers were visualized by means of SEM (Enterococcus faecalis; Parvimonas micra). RESULTS: Fibroblast proliferation depended on sealer and cultivation time. After 72 and 96 h GuttaFlow and EndoSequence BC showed relatively non-cytotoxic reactions, while Pulp Canal Sealer EWT and AH Plus Jet caused a significant decrease of cell proliferation (p<0.001). Visualization of cell growth and morphology with various fluorescent dyes supplemented the results. No antibacterial effect of EndoSequence BC to P. micra was found, whereas GuttaFlow showed a weak, Pulp Canal Sealer EWT and AH Plus Jet extensive growth inhibition. Also, no antibacterial effect of GuttaFlow, EndoSequence BC or AH Plus Jet to E. faecalis could be detected. CONCLUSIONS: These in vitro findings reveal that GuttaFlow and EndoSequence BC can be considered as biocompatible sealing materials. However, prior to their clinical employment, studies regarding their sealing properties also need to be considered.

Efficacy of Aquatain, a monomolecular surface film, against the malaria vectors Anopheles stephensi and An. gambiae s.s. in the laboratory.

Monomolecular films are used for mosquito control because of their asphyxiating effect on larvae and pupae. Compared with other films, Aquatain mosquito formulation (AMF) has an improved spreading ability and flexibility on a water surface. In the laboratory, AMF showed larvicidal, pupicidal, and oviposition deterrent effects against the malaria vectors Anopheles stephensi and An. gambiae. At a dose of 1 mL/m(2), the median lethal time to death for late larval instars was 3.02 (95% confidence interval [CI] = 2.76-3.25) and 0.98 (95% CI = 0.75-1.20) days for An. stephensi and An. gambiae, respectively. None of the treated larvae pupated. Pupal mortality reached 100% within two hours for both species. AMF repelled gravid females from ovipositing in treated oviposition cups. Without the choice of an untreated cup, the lowered water surface tension caused most females to drown while attempting to oviposit. This physical control method has the potential to become a safe, cost-effective, and resistance-proof malaria vector control tool.

Use of studded Polyflex stents in patients with neoplastic obstructions of the central airways.

BACKGROUND: The Polyflex is a commercially available silastic airway stent with proven efficacy. Due to a smooth outer surface its anchorage in the airway wall is superficial which may lead to stent migration. OBJECTIVE: To study the performance of an newer version of the Polyflex stent with a studded outer surface, which should improve anchorage. METHODS: In a 5-centre international study the new stent was prospectively tested in symptomatic patients with neoplastic central airway stenosis of more that 50% of normal diameter. Insertion technique, efficacy of stent placement and stent-related complications were recorded before, 1 month and 3 months post stent placement. RESULTS: Under general anaesthesia and rigid bronchoscopy 27 stents were inserted in 26 patients, mean age: 62 years (range: 37-83), 16 men. Diagnoses were 18 bronchogenic carcinoma, 4 oesophageal carcinoma, 2 metastases, 1 tracheal carcinoma, and 1 schwannoma. The stents were inserted in the following locations: 10 right main bronchus, 8 left main bronchus, 7 trachea, and 2 tracheo-bronchial. There was significant improvement in all functional parameters assessed from before (A), to 1 month (B) and 3 months (C) after stent placement. The measured values (mean +/- SD) were for the WHO scale: A: 2.7 (0.8), B: 1.5 (0.9), C: 1.6 (1.0); for the Karnofsky scale: A: 44 (19), B: 72 (18), C: 71 (21); for the Dyspnoea Index: A: 3.3 (0.7), B: 1.5 (0.8), C: 1.9 (1.2); for FEV(1): A: 1.2 (0.5), B: 1.9 (0.6), C: 1.5 (0.5), and for FVC: A: 2.1 (0.7), B: 2.8 (0.7), C: 2.5 (1.0). Stent-related complications were 4 reversible stent obstructions by secretions, 1 migration. The observation period was mean 4.3 months (range 2 days to 23 months). CONCLUSION: The studded Polyflex showed excellent efficacy, was very well tolerated, and had a very low migration rate. It presents an improvement over the older smooth model and can be considered a true alternative to the most widely used silastic stent, the Dumon stent.

Fibroblast behavior at aqueous interfaces with perfluorocarbon, silicone, and fluorosilicone liquids.

Perfluorocarbon, silicone, and fluorosilicone liquids with potential for use as vitreous substitutes in the management of complex retinal detachment were evaluated for surface reactivity by assessing the behavior of anchorage-dependent fibroblasts plated at the phase boundary between these compounds and culture medium. Low-viscosity perfluorcarbons were alumina-treated to remove polar impurities. On perfluorodecalin, perfluorodimethylcyclohexane, perfluorotrimethylcyclohexane, perfluoroethylcyclohexane, perfluorooctane, perfluoroperhydrophenanthrene, perfluoromethyladamantane, perfluorodimethyladamantane, the highly viscous perfluoropolyether liquids Krytox TLF7067 and 6354, and dimethylsiloxane liquids of a variety of viscosities, most cells did not attach; the few that did attach exhibited minimal spreading behavior and did not achieve the flattened spindle-shape morphology which is a prerequisite to normal proliferative activity. Conversely, on perfluoromethyldecaline, perfluorofluorene, perfluorotributylamine, the perfluoropolyether K-6 hexamer, trifluoropropylmethylsiloxane (fluorosilicone), and diphenyldimethylsiloxane, some cells became fusiform-shaped and exhibited proliferation, the extent of which varied with the compound. The association of alumina treatment of perfluorocarbon liquids with a reduction in cell growth was indicative of a relationship between the presence of residual hydrogen-containing impurities and the capacity for cellular attachment and growth. This correlation was demonstrated also in experiments in which cell attachment and growth was facilitated by the addition of hydrogen-rich monohydroperfluorooctane to alumina-treated perfluorooctane. In conclusion, evidence for the presence of surface active impurities in liquid vitreous substitute materials can be obtained by observing the behavior of attachment-dependent cells plated at the boundary between these compounds and culture medium.