Quasi-Diamond Platelet-Shaped Zinc Oxide Nanostructures Display Enhanced Antibacterial Activity.

The current study compares the antibacterial activity of zinc oxide nanostructures (neZnO). For this purpose, two bacterial strains, Escherichia coli (ATCC 4157) and Staphylococcus aureus (ATCC 29213) were challenged in room light conditions with the aforementioned materials. Colloidal and hydrothermal methods were used to obtain the quasi-round and quasi-diamond platelet-shape nanostructures. Thus, the oxygen vacancy (VO ) effects on the surface of neZnO are also considered to assess its effects on antibacterial activity. The neZnO characterization was achieved by X-ray diffraction (XRD), a selected area electron diffraction (SAED) and Raman spectroscopy. The microstructural effects were monitored by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Furthermore, optical absorption ultraviolet visible spectrophotometry (UV-Vis) and X-ray photoelectron spectroscopy (XPS) analyses complement the physical characterization of these nanostructures; neZnO caused 50 % inhibition (IC50 ) at concentrations from 0.064 to 0.072 mg/mL for S. aureus and from 0.083 to 0.104 mg/mL for E. coli, indicating an increase in activity against S. aureus compared to E. coli. Consequently, quasi-diamond platelet-shaped nanostructures (average particle size of 377.6±10 nm) showed enhanced antibacterial activity compared to quasi-round agglomerated particles (average size of 442.8±12 nm), regardless of Vo presence or absence.

Levofloxacin induces differential effects in the transcriptome between the gut, peripheral and axial joints in the Spondyloarthritis DBA/1 mice: Improvement of intestinal dysbiosis and the overall inflammatory process.

To analyze the effect of levofloxacin-induced intestinal microbiota modifications on intestinal, joint, and systemic inflammation in the DBA/1 mice with spontaneous arthritis. The study included two groups of mice, one of which received levofloxacin. The composition and structure of the microbiota were determined in the mice's stool using 16S rRNA sequencing; the differential taxa and metabolic pathway between mice treated with levofloxacin and control mice were also defied. The effect of levofloxacin was evaluated in the intestines, hind paws, and spines of mice through DNA microarray transcriptome and histopathological analyses; systemic inflammation was measured by flow cytometry. Levofloxacin decreased the pro-inflammatory bacteria, including Prevotellaceae, Odoribacter, and Blautia, and increased the anti-inflammatory Muribaculaceae in mice's stool. Histological analysis confirmed the intestinal inflammation in control mice, while in levofloxacin-treated mice, inflammation was reduced; in the hind paws and spines, levofloxacin also decreased the inflammation. Microarray showed the downregulation of genes and signaling pathways relevant in spondyloarthritis, including several cytokines and chemokines. Levofloxacin-treated mice showed differential transcriptomic profiles between peripheral and axial joints and intestines. Levofloxacin decreased the expression of TNF-α, IL-23a, and JAK3 in the three tissues, but IL-17 behaved differently in the intestine and the joints. Serum TNF-α was also reduced in levofloxacin-treated mice. Our results suggest that the microbiota modification aimed at reducing pro-inflammatory and increasing anti-inflammatory bacteria could potentially be a coadjuvant in treating inflammatory arthropathies.

A Novel Method for Carbon Nanotube Functionalization Using Immobilized Candida antarctica Lipase.

Carbon nanotubes (CNTs) have been proposed as nanovehicles for drug or antigen delivery since they can be functionalized with different biomolecules. For this purpose, different types of molecules have been chemically bonded to CNTs; however, this method has low efficiency and generates solvent waste. Candida antarctica lipase is an enzyme that, in an organic solvent, can bind a carboxylic to a hydroxyl group by esterase activity. The objective of this work was to functionalize purified CNTs with insulin as a protein model using an immobilized lipase of Candida antarctica to develop a sustainable functionalization method with high protein attachment. The functionalized CNTs were characterized by scanning electron microscope (SEM), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzymatic functionalization of insulin on the surface of the CNTs was found to have an efficiency of 21%, which is higher in conversion and greener than previously reported by the diimide-activated amidation method. These results suggest that enzymatic esterification is a convenient and efficient method for CNT functionalization with proteins. Moreover, this functionalization method can be used to enhance the cellular-specific release of proteins by lysosomal esterases.

Antimicrobial Resistance and Inorganic Nanoparticles.

Antibiotics are being less effective, which leads to high mortality in patients with infections and a high cost for the recovery of health, and the projections that are had for the future are not very encouraging which has led to consider antimicrobial resistance as a global health problem and to be the object of study by researchers. Although resistance to antibiotics occurs naturally, its appearance and spread have been increasing rapidly due to the inappropriate use of antibiotics in recent decades. A bacterium becomes resistant due to the transfer of genes encoding antibiotic resistance. Bacteria constantly mutate; therefore, their defense mechanisms mutate, as well. Nanotechnology plays a key role in antimicrobial resistance due to materials modified at the nanometer scale, allowing large numbers of molecules to assemble to have a dynamic interface. These nanomaterials act as carriers, and their design is mainly focused on introducing the temporal and spatial release of the payload of antibiotics. In addition, they generate new antimicrobial modalities for the bacteria, which are not capable of protecting themselves. So, nanoparticles are an adjunct mechanism to improve drug potency by reducing overall antibiotic exposure. These nanostructures can overcome cell barriers and deliver antibiotics to the cytoplasm to inhibit bacteria. This work aims to give a general vision between the antibiotics, the nanoparticles used as carriers, bacteria resistance, and the possible mechanisms that occur between them.

Trichoderma and Nanotechnology in Sustainable Agriculture: A Review.

Due to their unique properties and functionalities, nanomaterials can be found in different activities as pharmaceutics, cosmetics, medicine, and agriculture, among others. Nowadays, formulations with nano compounds exist to reduce the application of conventional pesticides and fertilizers. Among the most used are nanoparticles (NPs) of copper, zinc, or silver, which are known because of their cytotoxicity, and their accumulation can change the dynamic of microbes present in the soil. In agriculture, Trichoderma is widely utilized as a safe biocontrol strategy and to promote plant yield, making it susceptible to be in contact with nanomaterials that can interfere with its viability as well as its biocontrol and plant growth promotion effects. It is well-known that strains of Trichoderma can tolerate and uptake heavy metals in their bulk form, but it is poorly understood whether the same occurs with nanomaterials. Interestingly, Trichoderma can synthesize NPs that exhibit antimicrobial activities against various organisms of interest, including plant pathogens. In this study, we summarize the main findings regarding Trichoderma and nanotechnology, including its use to synthesize NPs and the consequence that these compounds might have in this fungus and its associations. Moreover, based on these findings we discuss whether it is feasible to develop agrochemicals that combine NPs and Trichoderma strains to generate more sustainable products or not.

Safe Administration of Carbon Nanotubes by Intravenous Pathway in BALB/c Mice.

Carbon nanotubes (CNTs) are nanomaterials with multiple possible uses as drug carriers or in nanovaccine development. However, the toxicity of CNTs administered intravenously in in vivo models has not been fully described to date. This work aimed to evaluate the toxic effect of pristine multi-walled CNTs (UP-CNTs), purified (P-CNTs), or CNTs functionalized with fluorescein isothiocyanate (FITC-CNTs) administered by intravenous injection in BALB/c mice. Biochemical and histopathological parameters were analyzed at 1, 14, 29, and 60 days post-exposure. Pristine CNTs were the most toxic nanoparticles in comparison with P-CNTs or FITC-CNTs, increasing serum AST (≈ 180%), ALT (≈ 300%), and LDH (≈ 200%) levels at one day post-exposure. The urea/creatinine ratio suggested pre-renal injury at the 14th day accompanied of extensive lesions in kidneys, lungs, and liver. Biochemical and histological findings in mice exposed to P-CNTs had not significant differences compared to the controls. A lower toxic effect was detected in animals exposed to FITC-CNTs which was attributable to FITC toxicity. These results demonstrate that the purification process of CNTs reduces in vivo toxicity, and that toxicity in functionalized CNTs is dependent on the functionalized compound. Therefore, P-CNTs are postulated as potential candidates for safe biomedical applications using an intravenous pathway.

Arsenic removal and activity of a sulfate reducing bacteria-enriched anaerobic sludge using zero valent iron as electron donor.

Arsenic (As) removal from water, subject to sulfate-reducing conditions has been shown to result in safe As levels. We evaluated sulfate-reducing activity and arsenic removal by an anaerobic sludge enriched with sulfate-reducing bacteria (SRB), using zero valent iron (ZVI) as electron donor and different concentrations of AsV or AsIII (up to 5 mg/L). Sulfate and As removal were monitored in aqueous samples of batch assays. Likewise, precipitates resulting from As removal were characterized in solids. Sulfate-reducing activity on the part of anaerobic sludge was slightly decreased by AsIII and it was 50% decreased, particularly at 5 mg/L AsV, for which arsenic removal equaled 98%. At all other As concentrations assayed, 100% As was removed. The co-existence of S, As and Fe in solids from assays with As, was demonstrated by scanning electron microscopy (SEM-EDS) and by micro-X-ray fluorescence, corroborating the possible formation of Fe-As-S type minerals for As precipitation. Pharmacosiderite and scorodite minerals were identified by micro-X-ray absorption near edge structure and confirmed by extended X-ray adsorption fine structure, and these were related to the oxidation of arsenopyrite during analysis. Results indicate the suitability of the anaerobic sludge for bioremediating arsenic-contaminated groundwater under sulfidogenic conditions with ZVI as electron donor.

Cell wall damage and oxidative stress in Candida albicans ATCC10231 and Aspergillus niger caused by palladium nanoparticles.

In this work the toxic effect of Palladium nanoparticles (PdNPs) was investigated in two eukaryotic cell models, Candida albicans and Aspergillus niger. PdNPs were synthesized by chemical reduction method, obtaining spherical NPs with a primary size ranging from 3 to 15 nm. PdNPs showed a hydrodynamic size of 1548 nm in Lee's minimum media. Minimal inhibitory concentration was determined at 200 and 250 ppm for Candida albicans and Aspergillus niger respectively, revealing a significant cell growth inhibition (ANOVA and tukey analysis, α = 0.5). Reactive Oxygen Species levels were increased in both microorganisms. Confocal, scanning and transmission electron microscopy studies revealed cell wall damage and cellular morphology changes, induced by the interaction of PdNPs, in both microorganisms.

New Methods of Esterification of Nanodiamonds in Fighting Breast Cancer-A Density Functional Theory Approach.

The use of nanodiamonds as anticancer drug delivery vehicles has received much attention in recent years. In this theoretical paper, we propose using different esterification methods for nanodiamonds. The monomers proposed are 2-hydroxypropanal, polyethylene glycol, and polyglicolic acid. Specifically, the hydrogen bonds, infrared (IR) spectra, molecular polar surface area, and reactivity parameters are analyzed. The monomers proposed for use in esterification follow Lipinski's rule of five, meaning permeability is good, they have good permeation, and their bioactivity is high. The results show that the complex formed between tamoxifen and nanodiamond esterified with polyglicolic acid presents the greatest number of hydrogen bonds and a good amount of molecular polar surface area. Calculations concerning the esterified nanodiamond and reactivity parameters were performed using Density Functional Theory with the M06 functional and the basis set 6-31G (d); for the esterified nanodiamond-Tamoxifen complexes, the semi-empirical method PM6 was used. The solvent effect has been taken into account by using implicit modelling and the conductor-like polarizable continuum model.

Oxidative damage to Pseudomonas aeruginosa ATCC 27833 and Staphylococcus aureus ATCC 24213 induced by CuO-NPs.

The cytotoxicity of nanoparticles (NPs) and their properties are important issues in nanotechnology research. Particularly, NPs affect the metabolism of microorganisms due to NP interactions with some biomolecules. In order to assess the mechanisms underlying NPs toxicity, we studied the damage caused by copper oxide nanoparticles (CuO-NPs) on Staphylococcus aureus ATCC 24213 and Pseudomonas aeruginosa ATCC 27833. Spherical CuO-NPs characterized by their diameter (13 ± 3 nm) were synthesized with a maximum of 254 nm. These NPs reduced cell viability, with a minimum inhibitory concentration (MIC) of 500 and 700 ppm for Staphylococcus aureus and Pseudomonas aeruginosa, respectively. Surfactant was added to reduce the NP agglomeration, but it did not present any effect. The mechanism of CuO-NPs as antimicrobial agent was assessed by analyzing solubilized Cu2+, quantifying DNA release in the culture media, and measuring intracellular reactive oxygen species (ROS). CuO-NPs induced severe damage on cells as revealed by confocal optical microscopy and scanning electron microscopy (SEM). Our results indicated that CuO-NPs interacted with bacteria, triggering an intracellular signaling network which produced oxidative stress, leading to ROS generation. Finally, we concluded that CuO-NPs exhibited higher antibacterial activity on Gram-negative bacteria than on Gram-positive ones.

Size effect of SnO2 nanoparticles on bacteria toxicity and their membrane damage.

Semiconductor SnO2 nanoparticles (NPs) are being exploited for various applications, including those in the environmental context. However, toxicity studies of SnO2 NPs are very limited. This study evaluated the toxic effect of two sizes of spherical SnO2 NPs (2 and 40 nm) and one size of flower-like SnO2 NPs (800 nm) towards the environmental bacteria E. coli and B. subtilis. SnO2 NPs were synthesized using a hydrothermal or calcination method and they were well characterized prior to toxicity assessment. To evaluate toxicity, cell viability and membrane damage were determined in cells (1 × 109 CFU mL-1) exposed to up to 1000 mg L-1 of NPs, using the plate counting method and confocal laser scanning microscopy. Spherical NPs of smaller primary size (E2) had the lowest hydrodynamic size (226 ± 96 nm) and highest negative charge (-30.3 ± 10.1 mV). Smaller spherical NPs also showed greatest effect on viability (IC50 > 500 mg L-1) and membrane damage of B. subtilis, whereas E. coli was unaffected. Scanning electron microscopy confirmed the membrane damage of exposed B. subtilis and also exhibited the attachment of E2 NPs to the cell surface, as well as the elongation of cells. It was also apparent that toxicity was caused solely by NPs, as released Sn4+ was not toxic to B. subtilis. Thus, surface charge interaction between negatively charged SnO2 NPs and positively charged molecules on the membrane of the Gram positive B. subtilis was indicated as the key mechanism related to toxicity of NPs.

Synthesis, biocompatibility and mechanical properties of ZrO2-Al2O3 ceramics composites.

This study evaluated cell viability, microhardness and flexural strength of two ceramic composites systems (ZA and AZ), pure alumina and zirconia. There were prepared homogeneous mixtures of 78wt%Al2O3+20wt%3Y-TZP+2wt%Al2O3w (AZ) and 80wt%3YTZP+18wt%Al2O3+2wt%Al2O3w (ZA), as well as 3Y-TZP (Z), pure Al2O3 (A) and commercial monolithic 3Y-TZP (Zc). Also mouse fibroblast cells 3T3-L1 and a MTT test was carried out at 24, 48 and 72 h. The surfaces were observed with SEM and the microhardness and three-point flexural strength values were estimated. The absolute microhardness values were: A>AZ>Z>Zc>ZA. Flexural strength of Zc, Z, and ZA were around double than AZ and A. All groups showed high biocompatibility trough cell viability values at 24, 48 and 72 h. Factors like grain shape, grain size and homogeneous or heterogeneous grain distributions may play an important role in physical, mechanical and biological properties of the ceramic composites.

Cytotoxicity of protein-carbon nanotubes on J774 macrophages is a functionalization grade-dependent effect.

Carbon nanotubes (CNTs) are used as carriers in medicine due to their ability to be functionalized with chemical substances. However, cytotoxicity analysis is required prior to use for in vivo models. The aim of this study was to evaluate the cytotoxic effect of CNTs functionalized with a 46 kDa surface protein from Entamoeba histolytica (P46-CNTs) on J774A macrophages. With this purpose, CNTs were synthesized by spray pyrolysis and purified (P-CNTs) using sonication for 48 h. A 46 kDa protein, with a 4.6-5.4 pI range, was isolated from E. histolytica HM1:IMSS strain trophozoites using an OFFGEL system. The P-CNTs were functionalized with the purified 46 kDa protein, classified according to their degree of functionalization, and characterized by Raman and Infrared spectroscopy. In vitro cytotoxicity was evaluated by MTT, apoptosis, and morphological assays. The results demonstrated that P46-CNTs exhibited cytotoxicity dependent upon the functionalized grade. Contrary to what was expected, P46-CNTs with a high grade of functionalization were more toxic to J774 macrophages than P46-CNTs with a low grade of functionalization, than P-CNTs, and had a similar level of toxicity as UP-CNT. This suggests that the nature of the functionalized protein plays a key role in the cytotoxicity of these nanoparticles.

Cytotoxicity of functionalized carbon nanotubes in J774A macrophages.

Cytotoxicity of carbon nanotubes (CNTs) is a prime concern for its use as antigen carriers. Here we evaluated the cytotoxic effect of unpurified (UP-CNTs), purified (P-CNTs), fluorescein isothiocyanate-functionalized (FITC-CNTs), and Entamoeba histolytica 220-kDa lectin-functionalized CNTs (L220-CNTs) in J774A macrophage (MOs) cell line. Cell viability and apoptosis were analyzed by MTT and TUNEL assays, respectively. Cyclooxygenase-2 (COX-2) was analyzed by reverse transcription-polymerase chain reaction. Cytotoxicity at 6.0 mg/L was higher with UP-CNTs > P-CNTs > FITC-CNTs, showing a decrease in cell viability and an increase in apoptosis. In contrast, MOs interacted with L220-CNTs showed an increase in cell viability without signs of apoptosis. Although UP-CNTs and P-CNTs exhibited COX-2 induction with 6.0 mg/L, functionalized CNTs were able to induce COX-2 at concentrations as low as 0.06 mg/L. These results suggest that functionalization decreases toxicity, and that L220-CNTs may be an excellent candidate for the production of a nanovaccine against amebiasis.

Microdureza profunda en una resina compuesta fotopolimerizada por diferentes fuentes de luz / Microhardness at depth of a dental composite resin fotocured troughthdiferents light sources

Introducción y Objetivo: Las lámparas fotopolimerizadoras son utilizadas actualmente en la práctica odontológica para estimular el endurecimiento de diferentes materiales de reconstruccióndental a base de resina compuesta, también llamada composite dental. El objetivo fue comparar la profundidad de polimerización provocada en una resina compuesta de uso dental, por dos sistemas convencionales de fotocurado y un láser Innova 300 adaptado experimentalmente a una longitud deonda de 488nm.

Introduction and Objective: The depth of polymerization caused in a dental composite resin through the fotoactivation with two conventional light sources and Innova 300 laser light adapted experimentally to 488nm length of wave were compared. Materials and Methods: 12 compositesamples were fotocured using 3 different sources of light in 2 different thickness dimensions,according to ISO 4049:2000 regulations. After 60 days of polymerization, micro hardness analyseswere carried out.

Influence of water temperature and salinity on seasonal occurrences of Vibrio cholerae and enteric bacteria in oyster-producing areas of Veracruz, México.

The influence of temperature and salinity on the occurrence of Vibrio cholerae, Escherichia coli and Salmonella spp. associated with water and oyster samples was investigated in two lagoons on the Atlantic Coast of Veracruz, Mexico over a 1-year period. The results indicated that seasonal salinity variability and warm temperatures, as well as nutrient influx, may influence the occurrence of V. cholera. non-O1 and O1. The conditions found in the Alvarado (31.12 degrees C, 6.27 per thousand, pH=8.74) and La Mancha lagoons (31.38 degrees C, 24.18 per thousand, pH=9.15) during the rainy season 2002 favored the occurrence of V. cholera O1 Inaba enterotoxin positive traced in oysters. Vibrio alginolyticus was detected in Alvarado lagoon water samples during the winter season. E. coli and Salmonella spp. were isolated from water samples from the La Mancha (90-96.7% and 86.7-96.7%) and Alvarado (88.6-97.1% and 88.6-100%) lagoons. Occurrence of bacteria may be due to effluents from urban, agricultural and industrial areas.