Development and application of methods for the determination of silver in polymeric dressings used for the care of burns

Titanium dioxide nanoparticles assessment in seaweeds by single particle inductively coupled plasma - Mass spectrometry

In this study, a first attempt for isolating and determining (characterising) background levels of titanium dioxide nanoparticles (TiO₂ NPs) in seaweed has been developed by using single particle inductively coupled plasma - mass spectrometry (SP-ICP-MS). Seaweeds were processed using an optimised ultrasound assisted extraction (UAE) procedure based on tetramethylammonium hydroxide (TMAH) before dilution and SP-ICP-MS analysis. The effect of the TMAH percentage in the extracting solution, as well as the volume of extracting solution and sonication (extraction) time, has been fully assessed. Additional experiments also showed that TiO₂ NPs were quantitatively released from the seaweed matrix in one UAE step since the analysis of residues gave TiO₂ NPs concentrations lower than the limit of quantification (LOQ) of the method. Validation of the method with 50 and 100 nm TiO₂ NPs (10 μg L^-1 as Ti) showed good analytical recovery (115% and 112% for 50 and 100 nm TiO₂ NPs, respectively), and good reproducibility (2% for size and 16% for number of TiO₂ NPs). Experiments regarding TiO₂ NPs stability showed that the extracted NPs are stable since there were not changes on the number of TiO₂ NPs and TiO₂ NPs size distributions when exposing TiO₂ NPs standards to the optimised extractive conditions.

Spatiotemporal distribution and speciation of silver nanoparticles in the healing wound

First observation of AgNPs dynamics in the wounds of real patients through elemental imaging and speciation.

Evaluation of anti-biofilm and cytotoxic effect of a gel formulation with Pluronic F-127 and silver nanoparticles as a potential treatment for skin wounds

The skin wounds cause serious burden to healthcare systems. The lack of sterility of the innate barrier function of the skin facilitates the development of microbial communities within the wound environment especially in biofilm form. Since biofilm is difficult to eradicate, new treatments have been established, such as silver nanoparticles (AgNPs), which antimicrobial and anti-biofilm properties have been studied, nevertheless, their toxic effects are known too. Different concentrations of AgNPs stabilized with a biocompatible and thermo-reversible vehicle as hydrogel Pluronic F-127 were synthesized, those formulations presented interesting thermo-reversibility which could be used to apply on wounds. The formulations (Gel 62.5, 125, and 250 ppm of AgNPs) proposed in this study showed in vitro a total inhibition of clinical strains (Staphylococcus aureus and Pseudomonas aeruginosa) in planktonic form, as well as, anti-biofilm activity was archived with the formulation of Gel 250 ppm, a total inhibition of biofilm formation with mixed culture was registered in the first 30 min of biofilm growth; even more, the viability of human fibroblasts with all gels formulations was >95%, in contrast to silver sulfadiazine cream 1% which showed the highest cytotoxic effect. PF-127 gel with AgNPs could be a prophylactic treatment for skin wounds, because its activity in critical steps on biofilm formation.

In Vitro Assessment of the Antibacterial Potential of Silver Nano-Coatings on Cotton Gauzes for Prevention of Wound Infections

Multidrug-resistant organisms are increasingly implicated in acute and chronic wound infections, thus compromising the chance of therapeutic options. The resistance to conventional antibiotics demonstrated by some bacterial strains has encouraged new approaches for the prevention of infections in wounds and burns, among them the use of silver compounds and nanocrystalline silver. Recently, silver wound dressings have become widely accepted in wound healing centers and are commercially available. In this work, novel antibacterial wound dressings have been developed through a silver deposition technology based on the photochemical synthesis of silver nanoparticles. The devices obtained are completely natural and the silver coatings are characterized by an excellent adhesion without the use of any binder. The silver-treated cotton gauzes were characterized through scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA) in order to verify the distribution and the dimension of the silver particles on the cotton fibers. The effectiveness of the silver-treated gauzes in reducing the bacterial growth and biofilm proliferation has been demonstrated through agar diffusion tests, bacterial enumeration test, biofilm quantification tests, fluorescence and SEM microscopy. Moreover, potential cytotoxicity of the silver coating was evaluated through 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide colorimetric assay (MTT) and the extract method on fibroblasts and keratinocytes. Inductively coupled plasma mass spectrometry (ICP-MS) was performed in order to determine the silver release in different media and to relate the results to the biological characterization. All the results obtained were compared with plain gauzes as a negative control, as well as gauzes treated with a higher silver percentage as a positive control.