Toxicity evaluation of novel imidacloprid nanoribbons, using somatic mutation and fitness indexes in Drosophila melanogaster.

Nanoribbons of imidacloprid, a systemic and chloronicotinyl insecticide, were successfully synthesized by laser-induced fragmentation/exfoliation of imidacloprid powders suspended in water, with widths ranging from 160 to 470 nm, lengths in the micron scale, and thickness of a few atoms layers. The aim of the present study was to examine the effects of acute and chronic exposure to imidacloprid (IMC) bulk and compare its effects with synthesized imidacloprid nanoribbons (IMCNR) on larval and adult viability, developmental time, olfactory capacity, longevity, productivity, and genotoxicity in Drosophila melanogaster. Larvae or adults were exposed at 0.01, 0.02, or 0.03 ppm to IMC or IMCNR. Results demonstrated that IMCNR produced a significant reduction in viability and olfactory ability. IMC did not significantly alter viability and olfactory ability. Similarly, marked differences on longevity were detected between treatment with IMC and IMCNR where the lifespan of males treated with IMC was significantly higher than control while IMCNR produced a reduction. As for productivity, developmental time, and genotoxicity, no marked differences were found between both forms of IMC.

Biocompatibility Evaluation of TiO2, Fe3O4, and TiO2/Fe3O4 Nanomaterials: Insights into Potential Toxic Effects in Erythrocytes and HepG2 Cells.

Nanomaterials such as titanium dioxide and magnetite are increasingly used in several fields, such as water remediation and agriculture. However, this has raised environmental concerns due to potential exposure to organisms like humans. Nanomaterials can cause adverse interactions depending on physicochemical characteristics, like size, morphology, and composition, when interacting with living beings. To ensure safe use and prevent the risk of exposure to nanomaterials, their biocompatibility must be assessed. In vitro cell cultures are beneficial for assessing nanomaterial-cell interactions due to their easy handling. The present study evaluated the biocompatibility of TiO2, Fe3O4, and TiO2/Fe3O4 nanomaterials thermally treated at 350 °C and 450 °C in erythrocytes and HepG2 cells. According to the hemolysis experiments, non-thermally treated NMs are toxic (>5% hemolysis), but their thermally treated counterparts do not present toxicity (<2%). This behavior indicates that the toxicity derives from some precursor (solvent or surfactant) used in the synthesis of the nanomaterials. All the thermally treated nanomaterials did not show hemolytic activity under different conditions, such as low-light exposure or the absence of blood plasma proteins. In contrast, non-thermally treated nanomaterials showed a high hemolytic behavior, which was reduced after the purification (washing and thermal treatment) of nanomaterials, indicating the presence of surfactant residue used during synthesis. An MTS cell viability assay shows that calcined nanomaterials do not reduce cell viability (>11%) during 24 h of exposure. On the other hand, a lactate dehydrogenase leakage assay resulted in a higher variability, indicating that several nanomaterials did not cause an increase in cell death as compared to the control. However, a holotomographic microscopy analysis reveals a high accumulation of nanomaterials in the cell structure at a low concentration (10 µg mL-1), altering cell morphology, which could lead to cell membrane damage and cell viability reduction.

Medicago sativa L. Plant Response against Possible Eustressors (Fe, Ag, Cu)-TiO2: Evaluation of Physiological Parameters, Total Phenol Content, and Flavonoid Quantification.

The present study analyzed Medicago sativa L. crops irrigated by TiO2 in the anatase phase and TiO2 doped with Ag, Fe, and Cu ions at 0.1%w synthesized using the sol-gel method (SG) and the sol-gel method coupled with microwave (Mw-SG). The materials were added to the irrigation water at different concentrations (50, 100, and 500 ppm). Stress induction by nanomaterials was observed by measuring stem morphology, chlorophyll index, total phenols and flavonoids, and antioxidant activity through the DPPH (2,2-diphenyl-1-picrylhydrazy) radical inhibition assay. The nanomaterial treatments caused statistically significant reductions in parameters such as stem length, leaf size, and chlorophyll index and increases in total phenol content and DPPH inhibition percentage. However, the observed effects did not show clear evidence regarding the type of nanomaterial used, its synthesis methodology, or a concentration-dependent response. By generally grouping the results obtained to the type of dopant used and the synthesis method, the relationship between them was determined employing a two-way ANOVA. It was observed that the dopant factors, synthesis, and interaction were relevant for most treatments. Additionally, the addition of microwaves in the synthesis method resulted in the largest number of treatments with a significant increase in the total content of phenols and the % inhibition compared to the traditional sol-gel synthesis. In contrast, parameters such as stem size and chlorophyll index were affected under different treatments from both synthesis methods.

Green Synthesis via Eucalyptus globulus L. Extract of Ag-TiO2 Catalyst: Antimicrobial Activity Evaluation toward Water Disinfection Process.

The problem of water pollution by persistent substances and microorganisms requires solutions that materials such as silver-modified titanium dioxide can provide due to their excellent photocatalytic and antimicrobial properties. However, the synthesis methods conventionally used to obtain these materials involve toxic chemical reagents such as sodium borohydride (NaBH4). The search for alternative synthesis methods that use environmentally friendly substances, such as the biosynthesis method, was evaluated. Silver-titanium dioxide (Ag-TiO2) was synthesized by a Eucalyptus globulus L. extract as a reductive agent through sol-gel and microwave-assisted sol-gel processes. Four different solvents were tested to extract secondary metabolites to determine their roles in reducing silver nanoparticles. Titanium dioxide nanoparticles with sizes from 11 to 14 nm were obtained in the anatase phase, and no narrowing of the bandgap was observed (3.1-3.2 eV) for the Ag-TiO2 materials compared with the pure TiO2. Interestingly, the bacterial inhibition values were close to 100%, suggesting an effective antimicrobial mechanism related to the properties of silver. Finally, by the physicochemical characterization of the materials and their antimicrobial properties, it was possible to obtain a suitable biosynthesized Ag-TiO2 material as a green option for water disinfection that may be compared to the conventional methods.

Development of a Nanostructured Platform for Identifying HER2-Heterogeneity of Breast Cancer Cells by Surface-Enhanced Raman Scattering.

Biosensor technology has great potential for the detection of cancer through tumor-associated molecular biomarkers. In this work, we describe the immobilization of the recombinant humanized anti-HER2 monoclonal antibody (trastuzumab) on a silver nanostructured plate made by pulsed laser deposition (PLD), over a thin film of Au(111). Immobilization was performed via 4-mercapto benzoic acid self-assembled monolayers (4-MBA SAMs) that were activated with coupling reagents. A combination of immunofluorescence images and z-stack analysis by confocal laser scanning microscopy (CLSM) allowed us to detect HER2 presence and distribution in the cell membranes. Four different HER2-expressing breast cancer cell lines (SKBR3 +++, MCF-7 +/-, T47D +/-, MDA-MB-231 -) were incubated during 24 h on functionalized silver nanostructured plates (FSNP) and also on Au(111) thin films. The cells were fixed by means of an ethanol dehydration train, then characterized by atomic force microscopy (AFM) and surface-enhanced Raman scattering (SERS). SERS results showed the same tendency as CLSM findings (SKBR3 > MCF-7 > T47D > MDA-MB-231), especially when the Raman peak associated with phenylalanine amino acid (1002 cm-1) was monitored. Given the high selectivity and high sensitivity of SERS with a functionalized silver nanostructured plate (FSNP), we propose this method for identifying the presence of HER2 and consequently, of breast cancer cells.

A Biological Approach for the Synthesis of Bismuth Nanoparticles: Using Thiolated M13 Phage as Scaffold.

We report the synthesis of Bi nanoparticles (Bi NPs) using the M13 phage as scaffold. The p8 protein of the phage is functionalized with thiol groups of different lengths, and these thiolated regions act as nucleation centers for Bi(3+) ions. The size distribution, shape, and resilience to oxidation of the Bi NPs depend on the length of the thiol group used. The NPs are characterized by high resolution transmission electron microscopy, Raman, and IR spectroscopies, matrix assisted laser desorption/ionization, and optical absorption. These results show that the nanoparticles are crystalline and have a typical diameter of ∼3.0 nm. The method of preparation presented here is reproducible and implies "greener" conditions than those reported elsewhere. To the best of our knowledge, this is the first report of bismuth nanoparticles synthesized by a biomineralization method.

Tribological properties of polymer nanohybrids containing gold nanoparticles obtained by laser ablation.

We have studied polystyrene (PS)+Au particles nanohybrids. Approximately spherical gold nanoparticles with the average diameter of 15 nm were obtained by laser ablation in a liquid environment. Thus any chemical residue on the particles was eliminated. Focused ion beam (FIB) milling plus scanning electron microscopy (SEM) observation show that Au particles are fairly well dispersed inside the polymer matrix, better than when PS is simply dissolved in a nanoparticle solution. The Au particles concentration as low as 0.15 wt% results in dramatic changes in tribological properties, namely dynamic friction and pin-on-disk wear. Both wear and dynamic friction results are explained in terms of high brittleness of PS, abrasion of Au particles against a ceramic indenter, and also effects of density of filler particles in the matrix on tribological properties. Effects of varying normal load on friction are small.