Multivalent network modifier upregulates bioactivity of multispecies biofilm-resistant polyalkenoate cement

AbstractReactive molecular additives have often been employed to tailor the mechanical properties of epoxy resins. In addition, several studies have reported improved electrical properties in such systems, where the network architecture and included function groups have been modified through the use of so-called functional network modifier (FNM) molecules. The study reported here set out to investigate the effect of a glycidyl polyhedral oligomeric silsesquioxane (GPOSS) FNM on the cross-linking reactions, glass transition, breakdown strength and dielectric properties of an amine-cured epoxy resin system. Since many previous studies have considered POSS to act as an inorganic filler, a key aim was to consider the impact of GPOSS addition on the stoichiometry of curing. Fourier transform infrared spectroscopy revealed significant changes in the cross-linking reactions that occur if appropriate stoichiometric compensation is not made for the additional epoxide groups present on the GPOSS. These changes, in concert with the direct effect of the GPOSS itself, influence the glass transition temperature, dielectric breakdown behaviour and dielectric response of the system. Specifically, the work shows that the inclusion of GPOSS can result in beneficial changes in electrical properties, but that these gains are easily lost if consequential changes in the matrix polymer are not appropriately counteracted. Nevertheless, if the system is appropriately optimized, materials with pronounced improvements in technologically important characteristics can be designed.

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A new method to solve a non-steady-state multispecies biofilm model

Bulletin of Mathematical Biology ◽

10.1007/bf02460699 ◽

1993 ◽

Vol 55 (6) ◽

pp. 1039-1061 ◽

Cited By ~ 7

Author(s):

Vincent Gadani ◽

Pierre Villon ◽

Jacques Manem ◽

Bruce Rittmann

Keyword(s):

Steady State ◽

New Method ◽

Biofilm Model ◽

Multispecies Biofilm

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A study of a multispecies biofilm in a submerged attached growth bioreactor

10.17760/d20235707 ◽

2004 ◽

Author(s):

Philip Bruno Pedros

Keyword(s):

Attached Growth ◽

Multispecies Biofilm

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Exopolysaccharides Produced by Streptococcus mutans Glucosyltransferases Modulate the Establishment of Microcolonies within Multispecies Biofilms

Journal of Bacteriology ◽

10.1128/jb.01649-09 ◽

2010 ◽

Vol 192 (12) ◽

pp. 3024-3032 ◽

Cited By ~ 262

Author(s):

H. Koo ◽

J. Xiao ◽

M. I. Klein ◽

J. G. Jeon

Keyword(s):

Streptococcus Mutans ◽

Extracellular Polysaccharide ◽

Fluorescence Labeling ◽

Tooth Surface ◽

Bacterial Cells ◽

Actinomyces Naeslundii ◽

Multispecies Biofilm ◽

Tooth Surfaces ◽

Glucan Synthesis

ABSTRACT Streptococcus mutans is a key contributor to the formation of the extracellular polysaccharide (EPS) matrix in dental biofilms. The exopolysaccharides, which are mostly glucans synthesized by streptococcal glucosyltransferases (Gtfs), provide binding sites that promote accumulation of microorganisms on the tooth surface and further establishment of pathogenic biofilms. This study explored (i) the role of S. mutans Gtfs in the development of the EPS matrix and microcolonies in biofilms, (ii) the influence of exopolysaccharides on formation of microcolonies, and (iii) establishment of S. mutans in a multispecies biofilm in vitro using a novel fluorescence labeling technique. Our data show that the ability of S. mutans strains defective in the gtfB gene or the gtfB and gtfC genes to form microcolonies on saliva-coated hydroxyapatite surfaces was markedly disrupted. However, deletion of both gtfB (associated with insoluble glucan synthesis) and gtfC (associated with insoluble and soluble glucan synthesis) is required for the maximum reduction in EPS matrix and biofilm formation. S. mutans grown with sucrose in the presence of Streptococcus oralis and Actinomyces naeslundii steadily formed exopolysaccharides, which allowed the initial clustering of bacterial cells and further development into highly structured microcolonies. Concomitantly, S. mutans became the major species in the mature biofilm. Neither the EPS matrix nor microcolonies were formed in the presence of glucose in the multispecies biofilm. Our data show that GtfB and GtfC are essential for establishment of the EPS matrix, but GtfB appears to be responsible for formation of microcolonies by S. mutans; these Gtf-mediated processes may enhance the competitiveness of S. mutans in the multispecies environment in biofilms on tooth surfaces.

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The Effects of Copper Addition on The Structure and Antibacterial Properties of Biomedical Glasses

10.1101/2020.01.24.918524 ◽

2020 ◽

Author(s):

Leyla Mojtabavi ◽

Amir Razavi

Keyword(s):

Antibacterial Properties ◽

Inhibition Zone ◽

X Ray Diffraction ◽

Network Modifier ◽

X Ray ◽

E Coli ◽

Copper Addition ◽

Xrd Patterns ◽

Copper Incorporation ◽

Glass Compositions

AbstractIn this work, we studied the effects of copper incorporation in the composition of bioactive glass. Three different glass compositions were synthesized with 0, 3, and 6 mol% of copper addition. X-Ray Diffraction (XRD) patterns confirmed that an amorphous microstructure was obtained for all three glass compositions. Results from Differential Thermal Analysis (DTA) showed that the copper addition in the glass lowers the glass transition temperature, from 646°C to 590°C when added at 6 mol%. X-ray Photoelectron (XPS) survey and high-resolution scans were performed to study the structural effects of copper addition in the glass. Results indicated that the incorporation of copper changes the ratio of bridging to non-birding oxygens in the structure. Glasses were further analyzed for their structure with Nuclear Magnetic Resonance (NMR) spectroscopy, which indicated that copper acts as a network modifier in the glass composition and copper-containing glasses show a less connected microstructure. Antibacterial efficacy of the glasses was analyzed against E. coli and S. epidermis. Copper-containing glasses showed a significantly higher inhibition zone compared to control glass. The glass with 6 mol% copper, exhibited inhibition zones of 9 and 16mm against E. coli and S. epidermis bacteria, respectively.

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