Antimicrobial Properties and Cytotoxicity of an Antimicrobial Monomer for Application in Prosthodontics

Purpose: This study aimed to investigate the antimicrobial properties and cytotoxicity of the monomer methacryloyloxyundecylpyridinium bromide (MUPB), an antiseptic agent capable of copolymerizing with denture base acrylic resins. Materials and Methods: The antimicrobial activity of MUPB was tested against the species Candida albicans, Candida dubliniensis, Candida glabrata, Lactobacillus casei, Staphylococcus aureus, and Streptococcus mutans. The minimum inhibitory and fungicidal/bactericidal concentrations (MIC, MFC/MBC) of MUPB were determined by serial dilutions in comparison with cetylpyridinium chloride (CPC). The cytotoxic effects of MUPB at concentrations ranging from 0.01 to 1 g/L were assessed by MTT test on L929 cells and compared with methyl methacrylate (MMA). The antimicrobial activity of copolymerized MUPB was tested by means of acrylic resin specimens containing three concentrations of the monomer (0, 0.3, 0.6% w/w). Activity was quantified by means of a disc diffusion test and a quantification of adhered planktonic cells. Statistical analysis employed the Mann-Whitney test for MIC and MFC/MBC, and ANOVA for the microbial adherence test (a= 0.05). Results: MUBP presented lower MIC values when compared with CPC, although differences were significant for C. dubliniensis and S. mutans only (p= 0.046 and 0.043, respectively). MFC/MBC values were similar for all species except C. albicans; in that case, MUPB presented significantly higher values (p= 0.046). MUPB presented higher cytotoxicity than MMA for all tested concentrations (p < 0.001) except at 0.01 g/L. Irrespective of the concentration incorporated and species, there was no inhibition halo around the specimens. The incorporation of MUPB influenced the adhesion of C. albicans only (p= 0.003), with lower CFU counts for the 0.6% group. Conclusions: It was concluded that non-polymerized MUPB has an antimicrobial capacity close to that of CPC and high cytotoxicity when compared with MMA. The antimicrobial activity of MUPB after incorporation within a denture base acrylic resin did not depend on its elution, but was shown to be restricted to C. albicans.

In vitro enterococcus faecalis biofilm formation on five adhesive systems

Objective: To determine the E. faecalis biofilm formation on the surface of five adhesive systems (AS) and its relationship with roughness. Study Design: The formation of E. faecalis biofilms was tested on the surface of four dual-cure AS: AdheSE DC, Clearfil DC Bond, Futurabond DC and Excite DSC and one light-cure antimicrobial AS, Clearfil Protect Bond, after 24 hours of incubation, using the MBEC high-throughput device. Results: E. faecalis biofilms grew on all the adhesives. The least growth of biofilm was on Excite DSC, Clearfil Protect Bond, and the control. Futurabond DC resulted in the greatest roughness and biofilm amount. There was a close relationship between the quantity of biofilm and roughness, except for Clearfil Protect Bond, which showed little biofilm but high roughness. Conclusion: None of the tested AS prevented E. faecalis biofilm formation, although the least quantity was found on the surface of Clearfil Protect Bond.

Saccharide based nanocapsules - From monomer building blocks to improved capsules properties

In dieser Arbeit wurde der vielfältige Nutzen von Kohlenhydraten in Nanokapsel Systemen untersucht. Drei verschiedene Nanokapsel-Typen wurden durch Reaktion an der Grenzfläche von inversen Miniemulsionen hergestellt. Es wurde gezeigt, dass die Kohlenhydrate nach Modifizierung als Monomer an der Kapselbildung teilnehmen können, oder zur Erhöhung der Sensitivität eines verkapselten Kontrastmittels beitragen können. Im Folgenden werden die Ergebnisse der einzelnen Projekte zusammengefasst. Eine neuartige Grenzflächen-Synthese zur Herstellung von Nanokapseln wurde entwickelt und untersucht. Bei der Reaktion handelt es sich um eine Ruthenium katalysierte Olefin-Kreuzmetathese, welche für die Reaktion an der Grenzfläche angepasst wurde. Als wasserlösliches Macromonomer wurde Dextranacrylat synthetisiert. Der Reaktionspartner war ein öl-löslichen Phosphoester (Phenyldi(undec-10-en-1-yl)phosphat). Anhand von NMR-Spektren wurde gezeigt, dass die Kapselbildung auf Olefin Kreuzmetathese beruht. Im Vergleich zu konventionellen Estern haben Phosphorester eine weitere Möglichkeit zur chemischen Funktionalisierung. Dies wurde exemplarisch durch die Verwendung von fluoreszenzmarkierten Phosphoestern gezeigt. Die Markierung wurde verwendet, um die pH-induzierte Abbaubarkeit der Nanokapseln mittels Fluoreszenz-Korrelations-Spektroskopie zu beobachten. Ziel des zweiten Projekts war es, Nanostrukturen zu entwickeln, um Infektionen mit Antibiotika-resistenten Bakterien lokal zu behandeln. Dazu wurden mit Dextranmethacrylat vernetzte Poly(acrylamid) basierte Nanogele synthetisiert und Zinknitrat zugesetzt. Die Synthese der Nanogele wurde erweitert, um durch Vernetzung freier Alkoholgruppen mit Toluoldiisocyanat eine Kapselschale zu erhalten. Die Schalenbildung spiegelte sich in einer geringeren Quellbarkeit der Gel- Schale-Hybride wieder. Die erhaltenen Gel-Schale-Hybride waren in der Lage das Wachstum von zwei Methicillin-resistenten Bakterienstämmen (S. aureus) zu unterdrücken und verzögern. Die synthetisierten Hybridstrukturen könnten in der Beschichtung von Wundauflagen Verwendung finden, um bakterielle Infektionen lokal und direkt nach Ausbruch zu behandeln. Ziel des dritten Projektes war es, die wichtigen Parameter in der Herstellung von Nanokapseln mit hoher Kontrastmittel Sensitivität zu identifizieren. Relaxivität/Signalsensitivität des Kontrastmittels ist von großer Bedeutung für die Bildgebung mittels MRI, dies kann durch die Begrenzung der Mobilität des Kontrastmittels erreicht werden. Aufgrund seiner hohen Komplexstabilität und seiner klinischen Bedeutung wurde das Kontrastmittel Gadobutrol für die Verkapselung verwendet. Das Kontrastmittel wurde in Polyharnstoff-Kapseln eingeschlossen, die durch einen inversen Miniemulsion-Prozess hergestellt wurden. Um die Viskosität im Inneren der Nanokapsel zu erhöhen, wurden zusätzlich Saccharose, Dextran und Polyacrylsäure verkapselt. In Gegenwart von Saccharose konnte die Relaxivität verdoppelt werden. Dies gründet sich vermutlich auf einem Second-sphere Effekt der Saccharose, einer auf Wasserstoffbrückenbindungen beruhende Interaktion von Kontrastmittel und Saccharose.

Copper-containing mesoporous bioactive glass scaffolds with multifunctional properties of angiogenesis capacity, osteostimulation and antibacterial activity

It is of great importance to develop multifunctional bioactive scaffolds, which combine angiogenesis capacity, osteostimulation, and antibacterial properties for regenerating lost bone tissues. In order to achieve this aim, we prepared copper (Cu)-containing mesoporous bioactive glass (Cu-MBG) scaffolds with interconnective large pores (several hundred micrometer) and well-ordered mesopore channels (around 5 nm). Both Cu-MBG scaffolds and their ionic extracts could stimulate hypoxia-inducible factor (HIF)-1a and vascular endothelial growth factor(VEGF) expression in human bone marrow stromal cells(hBMSCs). In addition, both Cu-MBG scaffolds and their ionic extracts significantly promoted the osteogenic differentiation of hBMSCs by improving their bone-related gene expression (alkaline phosphatase (ALP), osteopontin(OPN) and osteocalcin (OCN)). Furthermore, Cu-MBG scaffolds could maintain a sustained release of ibuprofen and significantly inhibited the viability of bacteria. This study indicates that the incorporation of Cu2þ ions into MBG scaffolds significantly enhances hypoxia-like tissue reaction leading to the coupling of angiogenesis and osteogenesis. Cu2þ ions play an important role to offer the multifunctional properties of MBG scaffold system. This study has demonstrated that it is possible to develop multifunctional scaffolds by combining enhanced angiogenesis potential, osteostimulation, and antibacterial properties for the treatment of large bone defects.

Randomized controlled trial : a randomized controlled clinical trial comparing a remineralizing paste with an antibacterial gel to prevent early childhood caries

PURPOSE: The purpose of this study was to compare twice daily tooth-brushing using 0.304 percent fluoride toothpaste alone with: (1) twice daily tooth-brushing plus once daily 10% casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste; and (2) twice daily tooth-brushing plus once daily 0.12% chlorhexidine gel (CHX) for reducing early childhood caries (ECC) and mutans streptococci (MS) colonization. METHODS: Subjects (n=622) recruited at birth were randomized to receive either CPP-ACP or CHX or no product (study control [SC]). All children were examined at 6, 12, and 18 months old in their homes, and at 24 months old in a community dental clinic. RESULTS: At 24 months old, the caries incidence was 1% (2/163) in CPP-ACP, 2% (4/180) in CHX, and 2% (3/188) in SC groups. In children who were previously MS colonized at 12 and 18 months old, 0% (0/11) and 5% (3/63), respectively, of the CPP-ACP group remained MS-positive versus 22% (2/9) and 72% (18/25) in CHX and 16% (4/25) and 50% (7/14) in SC groups (P<.001). CONCLUSIONS: There is insufficient evidence to justify the daily use of casein phosphopeptide-amorphous calcium phosphate or chlorhexidine gel to control early childhood caries.

Hybrid antibacterial fabrics with extremely high aspect ratio Ag/AgTCNQ nanowires

This study reports the synthesis of extremely high aspect ratios (>3000) organic semiconductor nanowires of Ag–tetracyanoquinodimethane (AgTCNQ) on the surface of a flexible Ag fabric for the first time. These one-dimensional (1D) hybrid Ag/AgTCNQ nanostructures are attained by a facile, solution-based spontaneous reaction involving immersion of Ag fabrics in an acetonitrile solution of TCNQ. Further, it is discovered that these AgTCNQ nanowires show outstanding antibacterial performance against both Gram negative and Gram positive bacteria, which outperforms that of pristine Ag. The outcomes of this study also reflect upon a fundamentally important aspect that the antimicrobial performance of Ag-based nanomaterials may not necessarily be solely due to the amount of Ag+ ions leached from these nanomaterials, but that the nanomaterial itself may also play a direct role in the antimicrobial action. Notably, the applications of metal-organic semiconducting charge transfer complexes of metal-7,7,8,8-tetracyanoquinodimethane (TCNQ) have been predominantly restricted to electronic applications, except from our recent reports on their (photo)catalytic potential and the current case on antimicrobial prospects. This report on growth of these metal-TCNQ complexes on a fabric not only widens the window of these interesting materials for new biological applications, it also opens the possibilities for developing large-area flexible electronic devices by growing a range of metal-organic semiconducting materials directly on a fabric surface.

Antibacterial anthranilic acid derivatives from Geijera parviflora

Five anthranilic acid derivatives, a mixture I of three new compounds 11′-hexadecenoylanthranilic acid (1), 9′-hexadecenoylanthranilic acid (2), and 7′-hexadecenoylanthranilic acid (3), as well as a new compound 9,12,15-octadecatrienoylanthranilic acid (4) together with a new natural product, hexadecanoylanthranilic acid (5), were isolated from Geijera parviflora Lindl. (Rutaceae). Their structures were elucidated by extensive spectroscopic measurements, and the positions of the double bonds in compounds 1-3 of the mixture I were determined by tandem mass spectrometry employing ozone-induced dissociation. The mixture I and compound 5 showed good antibacterial activity against several Gram-positive strains. © 2013 Elsevier B.V.

Hydrogen-bonded supramolecular polymers as self-healing hydrogels: Effect of a bulky adamantyl substituent in the ureido-pyrimidinone monomer

In an attempt to generate supramolecular assemblies able to function as self-healing hydrogels, a novel ureido-pyrimidinone (UPy) monomer, 2-(N ′-methacryloyloxyethylureido)-6-(1-adamantyl)-4[1H]-pyrimidinone, was synthesized and then copolymerized with N,N-dimethylacrylamide at four different feed compositions, using a solution of lithium chloride in N,N-dimethylacetamide as the polymerization medium. The assembling process in the resulting copolymers is based on crosslinking through the reversible quadruple hydrogen bonding between side-chain UPy modules. The adamantyl substituent was introduced in order to create a “hydrophobic pocket” that may protect the hydrogen bonds against the disruptive effect of water molecules. Upon hydration to equilibrium, all copolymers generated typical hydrogels when their concentration in the hydrated system was at least 15%. The small-deformation rheometry showed that all hydrated copolymers were hydrogels that maintained a solid-like behavior, and that their extrusion through a syringe needle did not affect significantly this behavior, suggesting a self-healing capacity in these materials. An application as injectable substitutes for the eye's vitreous humor was proposed

Plasma polymerization of 1,1,1-trichloroethane yields a coating with robust antibacterial surface properties

Novel, highly chlorinated surface coatings were produced via a one-step plasma polymerization (pp) of 1,1,1-trichloroethane (TCE), exhibiting excellent antimicrobial properties against the vigorously biofilm-forming bacterium Staphylococcus epidermidis.

Antibacterial Applications of Silver Nanoparticles Synthesized by Aqueous Extract of Azadirachta Indica (Neem) Leaves

Silver nanoparticles are known to have bactericidal effects. A new generation of dressings incorporating antimicrobial agents like silver nanoparticles is being formulated to reduce or prevent infections. The particles can be incorporated in materials and cloth rendering them sterile. Recently, it was found that aqueous silver ions can be reduced by aqueous extract of plant parts to generate extremely stable silver nanoparticles in water. Apart from being environmentally friendly process, use of Neem leaves extract might add synergistic antibacterial effect of Neem leaves to the biosynthesized nanoparticles. With this hypothesis the biosynthetic production of silver nanoparticles by aqueous extract of Neem leaves and its bactericidal effect in cotton cloth against E. Coli were studied in this work. Silver nanoparticles were synthesized by short term (1 day) and long term (21 days) interaction of Neem extract (20% w/v) and 0.01 M AgNO3 solution in 1:4 mixing ratio. The synthesized particles were characterized by UV visible spectroscopy, transmission electron microscopy, and incorporated into cotton disks by (i) centrifuging the disks with liquid broth containing nanoparticles, (ii) in-situ coating process during synthesis, and (iii) coating with dried and purified nanoparticles. The antibacterial property of the nanoparticles coated cotton disks was studied by disk diffusion method. The effect of consecutive washing of the coated disks with distilled water on antibacterial property was also investigated. This work demonstrates the possible use of biologically synthesized silver nanoparticles by its incorporation in cloths leading them to sterilization.

Standardised antibacterial Manuka honey in the management of persistent post-operative corneal oedema: A case series

Background Corneal oedema is a common post-operative problem that delays or prevents visual recovery from ocular surgery. Honey is a supersaturated solution of sugars with an acidic pH, high osmolarity and low water content. These characteristics inhibit the growth of micro-organisms, reduce oedema and promote epithelialisation. This clinical case series describes the use of a regulatory approved Leptospermum species honey ophthalmic product, in the management of post-operative corneal oedema and bullous keratopathy. Methods A retrospective review of 18 consecutive cases (30 eyes) with corneal oedema persisting beyond one month after single or multiple ocular surgical procedures (phacoemulsification cataract surgery and additional procedures) treated with Optimel Antibacterial Manuka Eye Drops twice to three times daily as an adjunctive therapy to conventional topical management with corticosteroid, aqueous suppressants, hypertonic sodium chloride five per cent, eyelid hygiene and artificial tears. Visual acuity and central corneal thickness were measured before and at the conclusion of Optimel treatment. Results A temporary reduction in corneal epithelial oedema lasting up to several hours was observed after the initial Optimel instillation and was associated with a reduction in central corneal thickness, resolution of epithelial microcysts, collapse of epithelial bullae, improved corneal clarity, improved visualisation of the intraocular structures and improved visual acuity. Additionally, with chronic use, reduction in punctate epitheliopathy, reduction in central corneal thickness and improvement in visual acuity were achieved. Temporary stinging after Optimel instillation was experienced. No adverse infectious or inflammatory events occurred during treatment with Optimel. Conclusions Optimel was a safe and effective adjunctive therapeutic strategy in the management of persistent post-operative corneal oedema and warrants further investigation in clinical trials.

In vitro antibacterial properties of tilmicosin against isolates of Histophilus somni from Australian cattle

A total of 27 isolates of Histophilus somni from Australian cattle were tested for in vitro sensitivity to tilmicosin by an agar dilution methodology. All 27 isolates were found to be sensitive.

Plasma polymerisation and retention of antibacterial properties of terpinen-4-ol

Plasma polymerisation was used to deposit thin oligomeric films of terpinen-4-ol on a range of substrates. The coatings were examined in terms of their chemical properties and surface architecture to ascertain the changes in chemical composition as a result of exposure to the plasma field. The antifouling and antimicrobial activity of oligomeric terpinen-4-ol coatings were then examined against such human pathogens as Staphylococcus aureus, Pseudomonas aeruginosa and Staphylococcus epidermis. The bacterial adhesion patterns were investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM) and confocal scanning laser microscopy (CSLM).

Investigation of potential antibacterial action for postharvest copper treatments of cut Acacia holosericea

The mechanisms of action of Cu 2+ in improving the longevity of cut flowers and foliage have not been elucidated. Possible antimicrobial action of Cu 2+ against stem end and vase solution colonising bacteria was investigated using Cu 2+ treatments optimised for cut Acacia holosericea A. Cunn. ex G. Don foliage stems. These treatments were a 5h pulse with 2.2mM Cu 2+ or a 0.5mM Cu 2+ vase solution versus a deionised water (no Cu 2+) control. Bacterial growth over time was assessed by a standard plate count agar technique and with scanning electron microscopy. Cu 2+ treatments significantly extended the cut foliage vase life. However, they did not have sustained antibacterial activity against stem end or vase solution colonising bacteria. Also, regular recutting of 1-2cm from the stem ends did not substantially improve either cut stem water relations or longevity. The positive effects of Cu 2+ treatments were unaffected by the repeated stem end recutting. It was concluded that the primary mechanism of Cu 2+ was not antibacterial. Moreover, naturally growing vase solution and stem end microbial populations had relatively insignificant effects on cut A. holosericea vase life. Research into alternative mechanisms of Cu 2+ is required. © 2012 Elsevier B.V.