BackgroundDiarrhea in piglets is one of the main causes of animal death after weaning; zinc oxide (ZnO) has been used in high doses for the control of this sickness. The aim of this study was to determine the physicochemical properties of ZnO nanoparticles synthesized and immobilized on a chitosan/alginate (CH/SA) complex and investigate the antimicrobial activity and in vitro release profile of zinc (Zn2+) from these new compounds. The ZnO nanoparticles composites were prepared and combined with CH/SA or CH/SA and sodium tripolyphosphate (TPP). The structure and morphology of the composites were analyzed by characterization methods such as X-ray diffraction, FTIR spectroscopy, thermogravimetric analysis, atomic absorption spectrophotometry and scanning electron microscopy.ResultsThe crystallite size of ZnO nano was 17 nm and the novel ZnO composites were effective in protecting ZnO in simulated gastric fluid, where Zn2+ reached a concentration six-fold higher than the levels obtained with the unprotected commercial-zinc oxide. In addition, the novel composites suggest effective antimicrobial activity against Escherichia coli and Staphylococcus aureus.
ConclusionsThe results described herein suggest that the novel nano composites may work as an alternative product for pig feeding as verified by the in vitro assays, and may also contribute to lower the zinc released in the environment by fecal excretion in animals waste.
Tuberculosis (TB) is one of the most fatal diseases and is responsible for the infection of millions of people around the world. Most recently, scientific frontiers have been engaged to develop new drugs that can overcome drug-resistant TB. Following this direction, using a designed scaffold based on the combination of two separate pharmacophoric groups, a series of menadione-derived selenoesters was developed with good yields. All products were evaluated for their
in vitro
activity against
Mycobacterium tuberculosis
H37Rv and attractive results were observed, especially for the compounds
8a
,
8c
and
8f
(MICs 2.1, 8.0 and 8.1 μM, respectively). In addition,
8a
,
8c
and
8f
demonstrated potent
in vitro
activity against multidrug-resistant clinical isolates (CDCT-16 and CDCT-27) with promising MIC values ranging from 0.8 to 3.1 μM. Importantly, compounds
8a
and
8c
were found to be non-toxic against the Vero cell line. The SI value of
8a
(>23.8) was found to be comparable to that of isoniazid (>22.7), which suggests the possibility of carrying out advanced studies on this derivative. Therefore, these menadione-derived selenoesters obtained as hybrid compounds represent promising new anti-tubercular agents to overcome TB multidrug resistance.
High-energy milling is the most widely used method in industry to achieve nanosized particles due to its low cost and potential to rapidly provide large-scale production. Using a top-down approach based on wet attritor milling, we investigated different combinations of the factors predicted from the 2 3 full-factorial design were investigated to process sodium-montmorillonite (Na-Mt). Statistical analyses were performed to determine the most suitable process conditions and to evaluate the factors influencing the response variable. Materials obtained from the different procedures were analyzed by energy dispersive x-ray spectroscopy, powder x-ray diffraction, nuclear magnetic resonance, Fourier transform infrared spectroscopy and dynamic light scattering. Particle surface, size and morphology were examined by scanning electron microscopy while the lamellar structure was observed by transmission electron microscopy. The results predicted using factorial design indicated that the milling time has a significant positive influence on the particle size of Na-Mt. The effect of rotation speed was nearly comparable and its impacts was similar to that of milling time. The interaction effects were significant at 99% confidence level (p<0.01). The optimal process conditions were: 3% Na-Mt concentration (w/v), 3 h of milling time and a rotation speed of 1867 rpm, resulting in a particle size of 282.23 nm. The proposed factorial model proved to be reliable and adequate (R 2 =0.9853, PredR 2 =0.9753 and AdjR 2 =0.9804). The wet attritor milling can be considered as an economical and effective alternative for the mechanical treatment of a wide variety of powders, aiming to achieve nanosized structures.
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