Acute toxicity study of antibacterial organophilic bentonite incorporated with geranyl acetate in mice and geranyl acetate liberation in simulated gastric fluid.

In the present study, the antibacterial property of the organophilic bentonite (Bent-ODA) and organophilic bentonite incorporated with geranyl acetate ester (Bent-ODA-GA) was evaluated against bacteria Staphylococcus aureus, Escherichia coli and Salmonella typhimurium. Oral acute toxicity of Bent-ODA-GA was evaluated in mice, by a single oral dose of 300 and 2000 mg kg-1. Animals were observed for any toxicity clinical signs or mortality for 15 days according to OECD 423 guidelines. The release assay of GA presents in Bent-ODA in simulated gastric fluid, pH 3.5 and pH 6.5 was also performed. Bent-ODA-GA composite presented antibacterial activity against S. aureus and S. typhimurium bacteria with 10.7 ± 0.6 mm and 2.2 ± 0.1 mm inhibition halo, respectively, which make it possible to associate the composite antimicrobial feature due to the ester presence. The composite did not reveal any toxicity signs or mortality in any animal for acute toxicity treatment during the 15 days observation period. The LD50 of Bent-ODA-DA was estimated to be greater than 2000 mg kg-1. It was also observed that geranyl acetate is released from Bent-ODA in concentrations lower than 0.03 mg kg-1 for pH 3.5 and 0.004 mg kg-1 for pH 6.5, which are lower than those that could cause some toxic effects in animals.

Microencapsulation of eugenol molecules by ß-cyclodextrine as a thermal protection method of antibacterial action.

Eugenol is natural oil that has excellent antibacterial properties but cannot be used to fabricate many products that require thermal processing. One possible alternative to the use of the eugenol molecules in high-temperature processes is the encapsulation of these molecules in a structure that is not toxic and is resistant to thermal treatment. This work investigated the encapsulation process of eugenol molecules in ß-cyclodextrine and the antibacterial properties of eugenol-ß-cyclodextrine (the eugenol-ßCD complex) against Escherichia coli and Staphylococcus aureus. The FTIR, DSC, MEV and TGA results show that the encapsulation method is an excellent alternative to increase the thermal stability of eugenol molecules. A value of 241.32L.mol-1 was determined for the formation constant (Kc) of the eugenol-ßCD complex, which confirmed the success of the encapsulation process. The MEV analysis shows the formation of approximately 12µm microcapsules. After the thermal treatment of the eugenol-ßCD complex at a temperature of 80°C for 2h, the complex retained significant antibacterial action, which confirms the thermal protection of the eugenol molecules. The minimum inhibitory concentration (MIC) and agar diffusion results show that the microcapsules containing 17.08mmol.L-1 of eugenol exhibited excellent antibacterial action against Escherichia coli and Staphylococcus aureus after thermal treatment.

Application of glass particles doped by Zn(+2) as an antimicrobial and atoxic compound in LLDPE and HDPE.

This study demonstrates the potential application of glass particles doped with Zn(+2) (GZn) as an atoxic, antimicrobial additive when used in conjunction with high density polyethylene (HDPE) and linear low density polyethylene (LLDPE) polymers. Toxicity tests demonstrated that these modified glass particles were nontoxic to human cells, and atomic absorption analyses demonstrated the migration of ionic species in quantities less than 2.0ppm for both the HDPE/GZn and LLDPE/GZn compounds. Microbiological tests demonstrated the antimicrobial effect of the pure GZn compound as well as the polymeric HDPE/GZn and LLDPE/GZn compounds. In addition, at percentages of GZn higher than 2.00wt.% and at a time of 4h, the bactericidal performance is excellent and equal for both polymeric compounds.

Evaluation of the toxic and genotoxic potential of acid mine drainage using physicochemical parameters and bioassays.

Carboniferous activity generates acid mine drainage (AMD) which is capable of unleashing toxic effects on the exposed biota. The aim of this study was to evaluate the toxic and genotoxic potential of untreated-AMD and AMD treated with calcinated sediment, using physicochemical parameters and bioassays. Results revealed that untreated-AMD presented low pH values and elevated concentrations of the metals Fe, Al, Mn, Zn and Cu. High acute toxicity was observed in Artemia sp. and Daphnia magna, and sub-chronic toxicity and genotoxicity in Allium cepa L. as well as scission of plasmid DNA exposed to untreated-AMD. Treatment of AMD with calcinated sediment promoted the reduction of acidity and the removal of metals, as well as a reduction in toxic and genotoxic effects. In conclusion, the calcinated sediment can be used as an alternative AMD treatment.

The influence of particle size and AgNO3 concentration in the ionic exchange process on the fungicidal action of antimicrobial glass.

Antimicrobial materials have long been used as an effective means of reducing the risks posed to humans by fungi, bacteria and other microorganisms. These materials are essential in environments where cleanliness, comfort and hygiene are the predominate concerns. This work presents preliminary results for the development of a fungicidal vitreous material that is produced by the incorporation of a silver ionic specimen through ionic exchange reactions. Silver ions were incorporated into powdered glass via ionic exchange in an ionic medium containing silver species with different concentrations of AgNO3. The fungicidal efficiency of the samples was studied as a function of the AgNO3 concentration and the particle size of the glass using the agar diffusion test for the microbiological analysis of the fungus species Candida albicans. The samples were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The experimental results showed that the fungicidal effect was dependent on the AgNO3 concentration in the ionic exchange medium but was not dependent on the particle size of the glass.