In Vitro Genotoxicity Evaluation of an Antiseptic Formulation Containing Kaolin and Silver Nanoparticles.

Worldwide antimicrobial resistance is partly caused by the overuse of antibiotics as growth promoters. Based on the known bactericidal effect of silver, a new material containing silver in a clay base was developed to be used as feed additive. An in vitro genotoxicity evaluation of this silver-kaolin clay formulation was conducted, which included the mouse lymphoma assay in L5178Y TK+/- cells and the micronucleus test in TK6 cells, following the principles of the OECD guidelines 490 and 487, respectively. As a complement, the standard and Fpg-modified comet assays for the evaluation of strand breaks, alkali labile sites and oxidative DNA damage were also performed in TK6 cells. The formulation was tested without metabolic activation after an exposure of 3 h and 24 h; its corresponding release in medium, after the continuous agitation of the silver-kaolin for 24 h was also evaluated. Under the conditions tested, the test compound did not produce gene mutations, chromosomal aberrations or DNA damage (i.e., strand breaks, alkali labile sites or oxidized bases). Considering the results obtained in the present study, the formulation seems to be a promising material to be used as antimicrobial in animal feed.

Antibacterial Activity of Kaolin-Silver Nanomaterials: Alternative Approach to the Use of Antibiotics in Animal Production.

According to the search for alternatives to replace antibiotics in animal production suggested in the antimicrobial resistance action plans around the world, the objective of this work was to evaluate the bactericidal effect of kaolin-silver nanomaterial for its possible inclusion as an additive in animal feed. The antibacterial activity of the C3 (kaolin-silver nanomaterial) product was tested against a wide spectrum of Gram-negative and Gram-positive bacteria (including multidrug resistant strains) by performing antibiograms, minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC), as well as growth inhibition curves against seven strains causing infections in animals. The C3 product generated inhibition halos in all the tested strains, and a higher activity against Gram-negative bacteria was found, with MBC values ranged from 7.8 µg/mL (P. aeruginosa) to 15.6 µg/mL (E. coli and Salmonella). In contrast, it was necessary to increase the concentration to 31.3 µg/mL or 250 µg/mL to eliminate 99.9% of the initial population of S. aureus ATCC 6538 and E. faecium ATCC 19434, respectively. Conversely, the inhibition growth curves showed a faster bactericidal activity against Gram-negative bacteria (between 2 and 4 h), while it took at least 24 h to observe a reduction in cell viability of S. aureus ATCC 6538. In short, this study shows that the kaolin-silver nanomaterials developed in the framework of the INTERREG POCTEFA EFA183/16/OUTBIOTICS project exhibit antibacterial activity against a wide spectrum of bacteria. However, additional studies on animal safety and environmental impact are necessary to evaluate the effectiveness of the proposed alternative in the context of One Health.

Electrochemical affinity biosensors for detection of mycotoxins: A review.

This review discusses the current state of electrochemical biosensors in the determination of mycotoxins in foods. Mycotoxins are highly toxic secondary metabolites produced by molds. The acute toxicity of these results in serious human and animal health problems, although it has been only since early 1960s when the first studied aflatoxins were found to be carcinogenic. Mycotoxins affect a broad range of agricultural products, most important cereals and cereal-based foods. A majority of countries, mentioning especially the European Union, have established preventive programs to control contamination and strict laws of the permitted levels in foods. Official methods of analysis of mycotoxins normally requires sophisticated instrumentation, e.g. liquid chromatography with fluorescence or mass detectors, combined with extraction procedures for sample preparation. For about sixteen years, the use of simpler and faster analytical procedures based on affinity biosensors has emerged in scientific literature as a very promising alternative, particularly electrochemical (i.e., amperometric, impedance, potentiometric or conductimetric) affinity biosensors due to their simplicity and sensitivity. Typically, electrochemical biosensors for mycotoxins use specific antibodies or aptamers as affinity ligands, although recombinant antibodies, artificial receptors and molecular imprinted polymers show potential utility. This article deals with recent advances in electrochemical affinity biosensors for mycotoxins and covers complete literature from the first reports about sixteen years ago.

An electrochemical immunosensor for ochratoxin A determination in wines based on a monoclonal antibody and paramagnetic microbeads.

We report a direct competitive immunosensor for the rapid determination of ochratoxin A (OTA) in wine samples. Magnetic beads (1 ± 0.5 µm diameter) covered with streptavidin were functionalized with a monoclonal antibody against OTA, and then left to incubate in a solution of tracer (ochratoxin conjugated to the enzyme peroxidase) and a range of OTA concentrations (10(-4) to 1,000 ng mL(-1)). After washing and separation steps helped with a magnetic field, a volume of the dispersion was put on screen-printed electrodes under a magnet, and after adding the substrate the p-benzoquinone generated enzymatically was detected by differential-pulse voltammetry. Wine samples (2 mL) were easily prepared simply by adjusting to pH = 7.5 with diluted NaOH and by adding polyvinylpyrrolidone for complexing polyphenols, without any other clean-up or preconcentration steps. The limit of detection for detecting OTA in wines was of 0.11 ± 0.01 ng L(-1), well below the permitted content of the mycotoxin by the European Union (<2 ng mL(-1)). Spiked wines were subjected to immunosensor calibrations to study the matrix effects. OTA concentrations measured with the immunosensor were compared with those obtained by high-performance liquid chromatography coupled to fluorescence detection (AOAC official method 2001.01). The OTA levels from two red wines of "Campo de Borja", Spain, ranged from about 0.027 to 0.033 ng mL(-1) of OTA.