Cashew-gum-based silver nanoparticles and palygorskite as green nanocomposites for antibacterial applications.

Nanocomposite materials have been proposed to enhance the properties of different materials. In this study, palygorskite (Pal) clay is proposed as a support matrix for silver nanoparticles stabilised with cashew gum (Anacardium occidentale L.) (AgNPs-CG), producing the Pal/AgNPs-CG nanocomposite, whose bactericidal activity was studied. AgNPs-CG was synthesised using a green method in which CG acted as a reducing and stabilising agent for these nanostructures. AgNPs-CGs were subsequently characterised then adsorbed to the Pal surface, which was previously treated to remove impurities such as quartz. Pal and Pal/AgNPs-CG were characterised by X-ray diffraction, specific surface area, thermal analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and transmission electron microscopy. The antibacterial activity assay by the direct contact method showed that the synergistic effect of the combination of AgNPs-CG and Pal increased the bactericidal effect of the nanomaterial compared with the AgNPs-CG activity, reaching a percentage inhibition of up to 70.2% against E. coli and 85.3% against S. aureus. Nanocomposite atoxicity was demonstrated by the Artemia Salina model. Thus, the Pal/AgNPs-CG nanocomposite emerges as a nanomaterial with potential antibacterial applications.

Comparison of Antimicrobial Activity between Chemical Disinfectants on Contaminated Orthodontic Pliers.

AIM: To compare the antimicrobial activity of the chemical substances--70% isopropyl alcohol, 2% glutaraldehyde (GTA) and 0.25% peracetic acid (PAA) in disinfecting orthodontic pliers contaminated in vitro with Streptococcui mutani, Staphylococci aureui and Candida albicani. MATERIALS AND METHODS: Distal end cutter pliers were divided into five groups: group 1 (negative control--sterilized pliers), group 2 (positive control--sterilized plier, subsequently contaminated), group 3 (disinfected with 70% isopropyl alcohol, friction method), group 4 (disinfected with 2% GTA, immersion method for 30 minutes), group 5 (disinfected with 0.25% peracetic acid (PAA), immersion method for 10 minutes). After the pliers were treated with one disinfectant and submitted to microbiological evaluation (by counting colony forming units), they were submitted to the same cleansing, sterilizing and contaminating processes, and were used in the following groups (crossover and washout study). The two-factor analysis of variance (ANOVA) test, followed by the Tukey test, was used to compare the groups. RESULTS: The results showed that there was no statistically significant difference between the three tested disinfectants. CONCLUSION: Although there were no statistically significant differences between the disinfectants, the chemical agents 2% glutaraldehyde and 0.25% PAA were effective in inhibiting the growth of the three microorganisms tested; however, 70% isopropyl alcohol was unable to completely eliminate S. aureui. CLINICAL SIGNIFICANCE: The chemical substances 2% glutaraldehyde and 0.25% PAA completely eliminated the microorganisms tested.