The development of a new desensitising mouthwash containing arginine, PVM/MA copolymer, pyrophosphates, and sodium fluoride--a hydraulic conductance study.

OBJECTIVE: To investigate the ability of a novel mouthwash comprised of 0.8% arginine, PVM/MA copolymer, pyrophosphates, and 0.05% sodium fluoride in an alcohol-free base (Pro-Argin™ Mouthwash Technology) to reduce dentine permeability. METHODS: Hydraulic conductance was used to assess the dentine permeability effects of the arginine mouthwash. Aqueous solutions containing arginine and PVM/MA copolymer were studied in the initial stage of the method development. The acid resistance was tested with a cola drink challenge. Finally, a blinded study was carried out to determine the occlusion of the arginine mouthwash in comparison to a negative control mouthwash. RESULTS: Dentine discs treated with the arginine mouthwash showed an average fluid reduction of 42%, which was statistically, significantly better than the fluid reduction for the negative control mouthwash. In addition, experiments using simple solutions of arginine and PVM/MA copolymer, alone and in combination, demonstrated that the combination of the two was required to provide a relevant occlusion benefit. Finally, the occlusion provided by the arginine mouthwash was maintained after exposure to an acid challenge. CONCLUSION: The exclusive combination of ingredients in the arginine mouthwash has been proven to be efficacious in decreasing dentine fluid flow as measured by hydraulic conductance. The new mouthwash works by occlusion, due to the unique combination of arginine, PVM/MA copolymer and pyrophosphates.

Mode of action studies of a new desensitizing mouthwash containing 0.8% arginine, PVM/MA copolymer, pyrophosphates, and 0.05% sodium fluoride.

OBJECTIVE: The mode of action of an arginine mouthwash using the Pro-Argin™ Mouthwash Technology, containing 0.8% arginine, PVM/MA copolymer, pyrophosphates and 0.05% sodium fluoride, has been proposed and confirmed as occlusion using a variety of in vitro techniques. METHODS: Quantitative and qualitative laboratory techniques were employed to investigate the mode of action of the new arginine mouthwash. Confocal laser scanning microscopy (CSLM) and atomic force microscopy (AFM) investigated a hydrated layer on dentine surface. Electron spectroscopy for chemical analysis (ESCA), secondary ion mass spectroscopy (SIMS) and near-infrared spectroscopy (NIR) provided information about its chemical nature. RESULTS: CLSM was used to observe the formation of a hydrated layer on exposed dentine tubules upon application of the arginine mouthwash. Fluorescence studies confirmed penetration of the hydrated layer in the inner walls of the dentinal tubules. The AFM investigation confirmed the affinity of the arginine mouthwash for the dentine surface, supporting its adhesive nature. NIR showed the deposition of arginine after several mouthwash applications, and ESCA/SIMS detected the presence of phosphate groups and organic acid groups, indicating the deposition of copolymer and pyrophosphates along with arginine. CONCLUSION: The studies presented in this paper support occlusion of the dentine surface upon the deposition of an arginine-rich layer together with copolymer and phosphate ions from an alcohol-free mouthwash containing 0.8% arginine, PVM/MA copolymer, pyrophosphates and 0.05% sodium fluoride.

Langmuir and Langmuir-Blodgett films containing a porphyrin-ruthenium complex.

The fabrication of supramolecular structures from the tetraruthenated porphyrin-containing phosphines, {TPyP[RuCl3(dppb)]4}, RuTPyP, is demonstrated with Langmuir and Langmuir-Blodgett films. The surface pressure-molecular area isotherms (pi-A) point to an edge-on arrangement for the RuTPyP molecules in the condensed state. Weak aggregation in the Langmuir films was indicated by non-zero surface potentials at large areas per molecule and a slight red shift in the ultraviolet-visible absorption spectrum in comparison to the spectrum in solution. Further aggregation occurs in the Z-type Langmuir-Blodgett films, which was confirmed with ultraviolet-visible spectroscopy of the deposited films. Fourier transform infrared and Raman spectroscopic data for powder and Langmuir-Blodgett films indicate that the RuTPyP molecules are chemically stable in Langmuir-Blodgett films regardless of the contact with water during film fabrication. The nanostructured nature of the Langmuir-Blodgett films was manifested in cyclic voltammetry due to the high sensitivity of the metallic centers in RuTPyP. Electrodes modified with Langmuir-Blodgett films exhibit an anodic peak at 100 mV and a cathodic peak at 7 mV, which is assigned to RuIII/RuII redox processes. Furthermore, Langmuir-Blodgett films from RuTPyP showed electrocatalytic activity for oxidation of benzyl alcohol, illustrated by a large shift of 100 mV in the anodic peak at 400 mV, while electropolymerized and cast films of the same compound displayed smaller and no activities, respectively.

The interaction between OPH and paraoxon at the air-water interface studied by AFM and epifluorescence microscopies.

The paraoxon hydrolysis reaction catalyzed by organophosphorus hydrolase (OPH) monolayer at the air-water interface was studied. OPH-paraoxon interactions, occurring at the two-dimensional interface, by close-packed, highly orientated OPH monolayer, were investigated by several different surface chemistry techniques; e.g. surface pressure area isotherms, atomic force microscopy (AFM), and in situ epifluorescence microscopy. The characterization of OPH Langmuir and Langmuir-Blodgett films prepared in both the presence and absence of paraoxon, demonstrated significantly distinctive feature when compared with one another. Continuous growth of the OPH aggregates is a distinct phenomenon associated with hydrolysis, in addition to the pH changes in the local environment of the enzyme macromolecules.

Self-doping effect in poly(o-methoxyaniline)/poly(3-thiopheneacetic acid) layer-by-layer films.

Nanostructured films from two conducting polymers, poly(o-methoxyaniline) (POMA) and poly(3-thiopheneacetic acid) (PTAA), were fabricated with the layer-by-layer (LBL) technique. The electrochemical response of the LBL films differs from that of a POMA cast film, even in a potential range where PTAA is inactive. This is attributed to differences in the diffusion-controlled charge and mass transport, where distinct ionic species participate in the LBL films, as demonstrated by quartz crystal microbalance measurements. The results show that the transport properties of conducting polymers can be changed by alternation with layers of appropriate materials in LBL films.

Langmuir and Langmuir-Blodgett films of organophosphorus acid anhydrolase.

In this paper, we describe the preparation and characterization of Langmuir and Langmuir-Blodgett (LB) monolayers of the enzyme organophosphorus acid anhydrolase (OPAA). Langmuir films of OPAA were characterized on different subphases, such as phosphate, ammonium carbonate, and bis-tris-propane buffers. Monolayers at the air-water interface were characterized by measuring the surface pressure and surface potential-area isotherms. In situ UV-vis absorption spectra were also recorded from the Langmuir monolayers. The enzyme activity at the air-water interface was tested by the addition of diisopropylfluorophosphate (DFP) to the subphase. LB films of OPAA were transferred to mica substrates to be studied by atomic force microscopy. Finally, a one-layer LB film of OPAA labeled with a fluorescent probe, fluorescein isothiocyanate (FITC), was deposited onto a quartz slide to be tested as sensor for DFP. The clear, pronounced response and the stability of the LB film as a DFP sensor show the potential of this system as a biosensor.

Layer-by-layer self-assembled chitosan/poly(thiophene-3-acetic acid) and organophosphorus hydrolase multilayers.

The aim of this study is to immobilize an enzyme, namely, organophosphorus hydrolase (OPH), and to detect the presence of paraoxon, which is an organophosphorus compound, using the layer-by-layer (LbL) deposition technique. To lift the OPH from the solid substrate, a pair of polyelectrolytes (positively charged chitosan (CS) and negatively charged poly(thiophene-3-acetic acid) (PTAA)) were combined. These species were made charged by altering the pH of the solutions. LbL involved alternate adsorption of the oppositely charged polyions from dilute aqueous solutions onto a hydrophilic quartz slide. This polyion cushion was held together by the electrostatic attraction between CS and PTAA. The growing process was monitored by fluorescence spectroscopy. OPH was then adsorbed onto the five-bilayer CS/PTAA system. This five-bilayer macromolecular structure compared to the solid substrate rendered stability to the enzyme by giving functional integrity in addition to the ability to react with paraoxon solutions. The ultimate goal is to use such a system to detect the presence of organophosphorus compounds with speed and sensitivity using the absorption and fluorescence detection methodologies.