An in vitro study of alginate oligomer therapies on oral biofilms.

OBJECTIVES: The in vitro effect of a novel, oligosaccharide nanomedicine OligoG against oral pathogen-related biofilms, both alone and in the presence of the conventional anti-bacterial agent triclosan, was evaluated. METHODS: The effect of OligoG±triclosan was assessed against established Streptococcus mutans and Porphyromonas gingivalis biofilms by bacterial counts and image analysis using LIVE/DEAD(®) staining and atomic force microscopy (AFM). The effect of triclosan and OligoG surface pre-treatments on bacterial attachment to titanium and polymethylmethacrylate was also studied. RESULTS: OligoG potentiated the antimicrobial effect of triclosan, particularly when used in combination at 0.3% against S. mutans grown in artificial saliva. OligoG was less effective against established P. gingivalis biofilms. However, attachment of P. gingivalis, to titanium in particular, was significantly reduced after surface pre-treatment with OligoG and triclosan at 0.01% when compared to controls. Light microscopy and AFM showed that OligoG was biocidal to P. gingivalis, but not S. mutans. CONCLUSIONS: OligoG and triclosan when used in combination produced an enhanced antimicrobial effect against two important oral pathogens and reduced bacterial attachment to dental materials such as titanium, even at reduced triclosan concentrations. Whilst the use of triclosan against oral bacteria has been widely documented, its synergistic use with OligoG described here, has not previously been reported. The use of lower concentrations of triclosan, if used in combination therapy with OligoG, could have environmental benefits. CLINICAL IMPORTANCE: The potentiation of antimicrobial agents by naturally occurring oligomers such as OligoG may represent a novel, safe adjunct to conventional oral hygiene and periodontal therapy. The ability of OligoG to inhibit the growth and impair bacterial adherence highlights its potential in the management of peri-implantitis.

Monolayers of Some Poly(oxyethylene)-Based Surfactants at the Air-Water Interface: The Effect of Structural Variations and Salt Concentration.

The Langmuir surface balance technique has been used to study the interfacial behavior of six structurally different poly(oxyethylene) (POE)-based polymer surfactants at the air-water interface. On a pure water subphase the surfactants have collapse surface pressures dependent on the POE chain length. The surfactant monolayers collapse at well-determined surface pressures, and the lower POE chain-length surfactants collapse at higher pressures than those with high POE content. This difference vanishes as increasing amounts of salt are added to the subphase. The PiA-isotherms are smooth, which is normal for polymeric surfactants. A closer analysis of the isotherms reveals characteristic behavior that can be attributed to structural differences. Similarities in thermodynamic behavior suggest that the molecular orientation is the same despite the structural differences. A new expression for the compressibility factor is developed to explain the relationship between this parameter and surface pressure for polymeric monolayers. Copyright 1999 Academic Press.

Surface Elasticity and Viscosity from Oscillating Bubbles Measured by Automatic Axisymmetric Drop Shape Analysis.

The pendant drop/sessile drop instrument developed by our group and based on video image analysis has been enhanced to measure oscillating drops and bubbles at a rate up to 25 pictures per second. Data analysis has been developed to analyze the results from sinusoidal oscillations in terms of dilatational surface elasticity and viscosity. The polymers ethylhydroxyethyl cellulose (EHEC) and two different poly(oxyethylene)-poly(oxypropylene) ABA block copolymers (PE6200 and PE6800) have been investigated at the air-water interface regarding rate of adsorption and surface dilatational properties. The polymers give surface pressures in the region 20-30 mN m-1, the surface elastic moduli are between 4 and 30 mN m-1, and the viscous moduli are generally low, from 0 to 6 mN m-1. The elastic moduli increase with increasing frequency, but both the slope and the concentration dependency vary. For the most water-insoluble polymer, EHEC, the modulus increases with polymer concentration, the relatively hydrophobic polymer PE6200 shows the opposite behavior, and the most water-soluble polymer, PE6800, shows a maximum in the equilibrium elasticity. These observations can be explained by the changes in the molecular orientation in the surface layer as reflected in pi vs A isotherms. The PE6200 polymer also shows a higher viscous modulus, which may be explained by diffusional transport between surface and bulk. Copyright 1998 Academic Press.