Tertiary Nanosystem Composed of Graphene Quantum Dots, Levofloxacin and Silver Nitrate for Microbiological Control.

BACKGROUND: Infectious diseases have the highest mortality rate in the world and these numbers are associated with scarce and/or ineffective diagnosis and bacterial resistance. Currently, with the development of new pharmaceutical formulations, nanotechnology is gaining prominence. METHODS: Nanomicelles were produced by ultrasonication. The particle size and shape were evaluated by scanning electron microscopy and confirmed by dynamic light scattering, also thermogravimetric analysis was performed to evaluate the thermal stability. Finally, antibacterial activity has been performed. RESULTS: The results showed that a rod-shaped nanosystem, with 316.1 nm and PDI of 0.243 was formed. The nanosystem was efficient against Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis subsp. spizizenii with MIC inferior to 0.98 and a synergistic effect between silver graphene quantum dots and levofloxacin was observed. CONCLUSION: The nanosystem produced may rise as a promising agent against the bacterial threat, especially regarding bacterial resistance.

Design Space Approach for Preservative System Optimization of an Anti-Aging Eye Fluid Emulsion.

The use of preservatives must be optimized in order to ensure the efficacy of an antimicrobial system as well as the product safety. Despite the wide variety of preservatives, the synergistic or antagonistic effects of their combinations are not well established and it is still an issue in the development of pharmaceutical and cosmetic products. The purpose of this paper was to establish a space design using a simplex-centroid approach to achieve the lowest effective concentration of 3 preservatives (methylparaben, propylparaben, and imidazolidinyl urea) and EDTA for an emulsion cosmetic product. Twenty-two formulae of emulsion differing only by imidazolidinyl urea (A: 0.00 to 0.30% w/w), methylparaben (B: 0.00 to 0.20% w/w), propylparaben (C: 0.00 to 0.10% w/w) and EDTA (D: 0.00 to 0.10% w/w) concentrations were prepared. They were tested alone and in binary, ternary and quaternary combinations. Aliquots of these formulae were inoculated with several microorganisms. An electrochemical method was used to determine microbial burden immediately after inoculation and after 2, 4, 8, 12, 24, 48, and 168 h. An optimization strategy was used to obtain the concentrations of preservatives and EDTA resulting in a most effective preservative system of all microorganisms simultaneously. The use of preservatives and EDTA in combination has the advantage of exhibiting a potential synergistic effect against a wider spectrum of microorganisms. Based on graphic and optimization strategies, we proposed a new formula containing a quaternary combination (A: 55%; B: 30%; C: 5% and D: 10% w/w), which complies with the specification of a conventional challenge test. A design space approach was successfully employed in the optimization of concentrations of preservatives and EDTA in an emulsion cosmetic product.

Avaliacao da eficacia antimicrobiana em condicionadores de cabelos / Evaluation of antimicrobial efficacy in hair conditioners

Condicionadores de cabelo, industrializados e comercializados em Sao Paulo, foram avaliados quanto a eficacia antimicrobiana de conservantes, frente a especificacao da Farmacopeia Britanica de 1988. Das 19 amostras, isentas de contaminacao viavel natural, 73,7% foram ativas contra Staphylococcus aureus e Pseudomonas aeruginosa e 94,4% contra Aspergillus niger. Em relacao a Candida albicans, das 15 amostras testadas, 93,3% nao se enquadram nessa especificacao. Analisando-se seis amostras com contaminacao natural observou-se que todas foram eficazes contra Aspergillus niger, mas apenas quatro frente a Pseudomonas aeruginosa