Structure-Activity Relationship for Quaternary Ammonium Compounds Hybridized with Poly(methyl methacrylate)

Hybrid films from poly (methylmethacrylate) (PMMA) and dioctadecyldimethylammonium bromide (DODAB), cetyltrimethylammonium bromide (CTAB), or tetrapropylammonium bromide (TPAB) were characterized by determination of wettability, ellipsometry, atomic force microscopy, active compounds diffusion to water, X-ray photoelectron spectroscopy (XPS) with determination of atomic composition on the films surface, and biocidal activity against Pseudomonas aeruginosa or Staphylococcus aureus. QAC mobility in the films increased from DODAB to CTAB to TPAB. Diffusion and optimal hydrophobic hydrophilic balance imparted the highest bioactivity to CTAB. DODAB sustained immobilization at the film surface killed bacteria upon contact. TPAB ability to diffuse was useless because of its unfavorable hydrophobic hydrophilic balance for bioactivity.FAPESPFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNP

Antimicrobial Particles from Emulsion Polymerization of Methyl Methacrylate in the Presence of Quaternary Ammonium Surfactants

The purpose of this Article is to characterize polymeric particles of poly­(methylmethacrylate) (PMMA) synthesized in the presence of one of two different quaternary ammonium surfactants (QACs): cetyltrimethylammonium bromide (CTAB) or dioctadecyldimethylammonium bromide (DODAB). The methods used are dynamic light scattering for sizing, polydispersity and zeta potential analysis, scanning electron microscopy (SEM) for morphology visualization, and plating plus colony-forming unities (CFU) counting for the determination of antimicrobial activity. The results point out the high QAC concentration required to obtain cationic and bioactive antimicrobial particles with good colloidal stability and a permanent load of the polymeric network with QACs. Over a range of micromolar QAC concentrations, there is remarkable antimicrobial activity of PMMA/CTAB or PMMA/DODAB particles, which is much higher than those determined for the QACs by themselves. Loading the biocompatible polyacrylate particles with QACs is a facile, fast, low-cost approach to obtaining highly efficient antimicrobial nanoparticles

Antibacterial effect (in vitro) of Moringa oleifera and Annona muricata against Gram positive and Gram negative bacteria Efeito antibacteriano (in vitro) de Moringa oleifera (moringa) e Annona muricata (graviola) frente a bactérias Gram-negativas e Gram-positiva

Antibacterial effects of aqueous and ethanolic extracts of seeds of moringa (Moringa oleifera) and pods of soursop (Annona muricata) in the concentration of 1:5 and 1:10 in volumes 50, 100, 150 and 200 µL were examined against Staphylococcus aureus, Vibrio cholerae, Escherichia coli (isolated from the organism and the aquatic environment) and Salmonella Enteritidis. Antibacterial activity (inhibition halo > 13 mm) against S. aureus, V. cholerae and E. coli isolated from the whiteleg shrimp, Litopenaeus vannmaei, was detected in aqueous and ethanolic extracts of moringa. E. coli isolated from tilapiafish, Oreochromis niloticus, was sensitive to the ethanolic extract of moringa. The aqueous extracts of soursop showed an antibacterial effect against S. aureus and V. cholerae, but the antibacterial activity by the ethanol extracts of this plant was not demonstrated.<br>Para avaliação do efeito bactericida frente à Staphylococcus aureus, Vibrio cholerae, Escherichia coli (isolada de pescados e ambiente aquático) e Salmonella Enteretidis, foram testados extratos aquosos e etanólicos de sementes de moringa (Moringa oleifera) e casca de graviola (Annona muricata) na concentração de 1:5 e 1:10, nos volumes de 50, 100, 150 e 200 µL. Os resultados mostraram efeito antibacteriano (halo de inibição > 13mm) dos extratos aquosos e etanólicos de moringa frente a S. aureus, V. cholerae e E. coli isoladas de camarão cinza Litopenaeus vannmaei. A cepa de E. coli isolada do pescado Oreochromis niloticus apresentou sensibilidade frente ao extrato etanólico de moringa. Os extratos aquosos de graviola apresentaram efeito bactericida frente a S. aureus e V. cholerae, entretanto, os extratos etanólicos dessa planta não mostraram atividade antibacteriana