RESUMO

Rigid polyurethane foams were prepared by the one-step expandable foam method using casting molding followed by forming clay-based composites. Polyurethane/vermiculite foam composites (PU/VMT) were controlled based on adding the percentage of clay in the formulation. The effects of composite modifications were evaluated by X-ray diffraction (XRD), thermogravimetric analysis (TG/DTG), and scanning electron microscopy (SEM/EDS) applied to the flame retardancy explored by the vertical burn test. The results indicated that adding clay controlled the particle size concerning polyurethane (PU) foams. However, they exhibited spherical structures with closed cells with relatively uniform distribution. XRD analysis showed the peaks defined at 2θ = 18° and 2θ = 73° relative to the crystallinity in formation and interaction of rigid segments were identified, as well as the influence of crystallinity reduction in composites. In the flame test, the flame retardant surface was successful in all composites, given the success of the dispersibility and planar orientation of the clay layers and the existence of an ideal content of vermiculite (VMT) incorporated in the foam matrix.

RESUMO

Modified polysaccharides have been featured as new agents against bacterial infection presenting biocompatibility in their use for medical purposes. In this work, we carried out the quaternization of Angico gum (AG). Quaternized Angico gum derivatives (QAG) were produced using a cationic moiety (3-Chloro-2-hydroxypropyl)trimethylammonium chloride onto the gum backbone. The products were characterized by FT-IR spectroscopy, Zeta potential, elemental analysis, and 1H NMR and degree of substitution (DS) was calculated. QAG were also evaluated for their anti-staphylococcal activity by determining Minimum Inhibitory and Bactericidal concentrations against pathogenic Staphylococcus spp. and by imaging using Atomic Force Microscopy. The hemolysis test and Galleria mellonella model were used to assess toxicity of gums. Our results showed that derivatives who presented highest DS (QAG-A3, 0.48 and QAG-B, 0.54) showed more effective antibacterial activity against tested bacteria, biocompatibility with erythrocytes and non-toxicity in G. mellonella model.

Assuntos

Antibacterianos , Inseticidas , Mariposas/crescimento & desenvolvimento , Gomas Vegetais/química , Staphylococcus/crescimento & desenvolvimento , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Avaliação Pré-Clínica de Medicamentos , Inseticidas/química , Inseticidas/farmacologia

RESUMO

Chemical modifications to cashew gum (CG) structure have been previously reported to obtain new physicochemical characteristics, however until now there were no reports of modifications by introduction of new functional groups to add cationic character. This study presents a quaternization route for CG using a quaternary ammonium reagent. The chemical features of the quaternized cashew gum derivatives (QCG) were analyzed by: FTIR, elemental analysis, degree of substitution, Zeta potential, 1H NMR and 1H-13C correlation (HSQC). QCG were evaluated for their anti-staphylococcal activity by determining minimum inhibitory and bactericidal concentrations against pathogenic Staphylococcus spp. and by imaging using atomic force microscopy. Moreover, the mammalian cell biocompatibility were also assessed through hemolytic and cell toxicity assays. QCG presented promising antimicrobial activity against methicillin-resistant S. aureus and biocompatibility on tested cells. These results show that QCG could be a promising tool in the development of biomaterials with an anti-septic action.

Assuntos

Anacardium/química , Antibacterianos/química , Gomas Vegetais/química , Animais , Materiais Biocompatíveis/química , Linhagem Celular , Eritrócitos/efeitos dos fármacos , Hemólise , Humanos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Camundongos , Testes de Sensibilidade Microbiana , Polímeros , Staphylococcus/efeitos dos fármacos

RESUMO

The present study describes the development of a green synthesis of silver nanoparticles reduced and stabilized by exuded gum from Anacardium occidentale L. and evaluates in vitro their antibacterial and cytotoxic activities. Characterization of cashew gum-based silver nanoparticles (AgNPs) was carried out based on UV-Vis spectroscopy, transmission electron microscopy and dynamic light scattering analysis which revealed that the synthesized silver nanoparticles were spherical in shape, measuring about 4 nm in size with a uniform dispersal. AgNPs presented antibacterial activity, especially against Gram-negative bacteria, in concentrations where no significant cytotoxicity was observed.