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A rapid, eco-friendly, and simple method for the synthesis of long-lasting (2 years) silver nanoparticles (AgNPs) is reported using aqueous leaf and petal extracts of Tagetes erecta L. The particles were characterized using UV-Visible spectrophotometry and the analytical and crystallographic techniques of transmission electron microscopy (TEM). The longevity of the AgNPs was studied using UV-Vis and high-resolution TEM. The antibacterial activity of the particles against Erwinia amylovora was evaluated using the Kirby-Bauer disk diffusion method. The results were analyzed using ANOVA and Tukey's test (p ≤ 0.05). Both the leaf and petal extracts produced AgNPs, but the leaf extract (1 mL) was long-lasting and quasi-spherical (17.64 ± 8.87 nm), with an absorbance of UV-Vis λmax 433 and a crystalline structure (fcc, 111). Phenols, flavonoids, tannins, and terpenoids which are associated with -OH, C=O, and C=C were identified in the extracts and could act as reducing and stabilizing agents. The best antibacterial activity was obtained with a nanoparticle concentration of 50 mg AgNPs L-1. The main contribution of the present research is to present a sustainable method for producing nanoparticles which are stable for 2 years and with antibacterial activity against E. amylovora, one of most threatening pathogens to pear and apple productions.

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In this work, the photocatalytic activity of nanoparticles (NPs) of zinc oxide synthetized by Prosopis laevigata as a stabilizing agent was evaluated in the degradation of methylene blue (MB) dye under UV radiation. The theoretical study of the photocatalytic degradation process was carried out by a Langmuir-Hinshelwood-Hougen-Watson (LHHW) model. Zinc oxide nanoparticles were synthesized by varying the concentration of natural extract of Prosopis laevigata from 1, 2, and 4% (weight/volume), identifying the samples as ZnO_PL1%, ZnO_PL2%, and ZnO_PL4%, respectively. The characterization of the nanoparticles was carried out by Fourier transform infrared spectroscopy (FT-IR), where the absorption band for the Zn-O vibration at 400 cm-1 was presented; by ultraviolet-visible spectroscopy (UV-vis) the value of the band gap was calculated, resulting in 2.80, 2.74 and 2.63 eV for the samples ZnO_PL1%, ZnO_PL2%, and ZnO_PL4%, respectively; XRD analysis indicated that the nanoparticles have a hexagonal zincite crystal structure with an average crystal size of 55, 50, and 49 in the sample ZnO_PL1%, ZnO_PL2%, and ZnO_PL4%, respectively. The morphology observed by TEM showed that the nanoparticles had a hemispherical shape, and the ZnO_PL4% sample presented sizes ranging between 29 and 45 nm. The photocatalytic study showed a total degradation of the MB in 150, 120, and 60 min for the samples ZnO_PL1%, ZnO_PL2%, and ZnO_PL4%, respectively. Also, the model explains the experimental observation of the first-order kinetic model in the limit of low concentrations of dye, indicating the influence of the mass transfer processes.

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Candida albicans (ATCC SC5314) was exposed to biosynthesized copper oxide nanoparticles (CuONPs) to determine their inhibitory capacity. Nanoparticles were polydisperse of small size (5.8 ± 3.5 nm) with irregular shape. The minimum inhibitory concentration (MIC) against C. albicans was 35.5 µg/mL. The production of reactive oxygen species (ROS) of C. albicans was verified when exposed to different concentrations of CuONPs. Ultrastructural analysis of C. albicans revealed a high concentration of CuONPs in the cytoplasm and outside the cell; also, nanoparticles were detected within the cell wall. Cytotoxic analyses using fibroblasts (L929), macrophages (RAW 264.7), and breast (MCF-12) cell lines show good results of cell viability when exposed at the MIC. Additionally, a hemocompatibility analysis was carried out and was found to be below 5%, considered the threshold for biocompatibility. Therefore, it is concluded that the biosynthesized CuONPs have a high potential for developing a topical antifungal treatment.

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BACKGROUND: The encapsulation of anti-cancer drugs in stimulus-sensitive release systems may provide advantages such as enhanced drug toxicity in tumour tissue cells due to increased intracellular drug release. Encapsulation may also improve release in targeted tissue due to the response to a stimulus such as pH, which is lower in the tumour tissue microenvironment. Here, we evaluated the in vitro toxicity of the Drug Doxorubicin (DOX) loaded into a release system based on poly(ß-amino ester)- modified MCM-41 silica nanoparticles. METHODS: The MCM-41-DOX-PbAE release system was obtained by loading DOX into MCM-41 nanoparticles amino-functionalized with 3-aminopropyltriethoxysilane (APTES) and then coated with a pH-responsive poly(ß-amino ester) (PbAE). The physicochemical characteristics of the release system were evaluated through TEM, FTIR and TGA. Cytotoxicity assays were performed on the MCM-41- DOX-PbAE system to determine their effects on the inhibition of human MCF-7 breast cancer cell proliferation after 48 h of exposure through crystal violet assay; the investigated systems included MCF-7 cells with MCM-41, PbAE, and MCM-41-PbAE alone. Additionally, the release of DOX and the change in pH in vitro were determined. RESULTS: The physicochemical characteristics of the synthesized MCM-41-PbAE system were confirmed, including the nanoparticle size, spherical morphology, mesoporous ordered structure, and presence of PbAE on the surface of the MCM-41 nanoparticles. Likewise, we demonstrated that the release of DOX from the MCM-41-DOX-PbAE system promoted an important reduction in MCF-7 cell viability (~ 70%) compared to the values obtained with MCM-41, PbAE, and MCM-41-PbAE, as well as a reduction in the viability under treatment with just DOX (~ 50%). CONCLUSION: The results suggest that all the components of the release system are biocompatible and that the encapsulation of DOX in MCM-41-PbAE could allow better intracellular release, which would probably increase the availability and toxic effect of DOX.

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Bionanotechnology is a relatively new term that implies the use of some biological material or organisms in order to prepare nanosystems or nanoparticles. This work presents the preparation and bactericide application of a sustainable nanometric system (silver nanoparticles) using a waste biological support (bovine bone powder). This system was prepared by the method of metallic salt reduction, using NaBH4 as reducing agent and AgNO3 as metallic salt. Two silver contents were analyzed, 1% and 5% weight. The latter was found to be more efficient than the former. Transmission electronic microscopy shows an average size of 10.5 ± 3.3 nm and quasi-sphere morphology. The antimicrobial assay shows that a 5% weight content of silver had a bactericide effect for Escherichia coli at 46.8 min of exposure. The minimum inhibitory concentration (MIC) of silver nanoparticles supported on bovine bone powder for Escherichia coli was 7.5 µg/mL. The biocomposite exhibits a specific antibacterial kinetics constant (k) of 0.1128 min-1 and decimal reduction time (DRT) of 20.39 min for Escherichia coli. Thus, it was concluded that a biocomposite was prepared with a biodegradable, waste, and low-cost support, under mild conditions (room temperature and atmospheric pressure) and using water as solvent.

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In the present study, two agro-industrial wastes, sugarcane bagasse, and peanut shell were employed as support of magnetite nanoparticles for the synthesis of magnetic bio-composites: magnetic sugarcane bagasse (MBO) and magnetic peanut shell (MPSo). The presence of magnetite was verified by Raman spectroscopy. Magnetic nanoparticles shape and size distribution were studied by TEM, while composites morphologies were observed by SEM. Structural characteristics of the pesticides and their possible chemical adsorption on composites were analyzed by FTIR. The removal was carried out by a batch adsorption process, and UV-VIS technique was used for pesticide concentration estimation. Elovich model described better all systems pointing out to a chemical adsorption process occurring. Experimental data isotherms of carbofuran and iprodione can be best explained by more than one mathematical model, but Sip was the ordinary equation in all systems. Maximum adsorption capacities of 175 and 89.3 mg/g for carbofuran, and 119 and 2.76 mg/g for iprodione, were obtained for MBo and MPSo, respectively.

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Surface-enhanced Raman scattering (SERS) is a surface-sensitive technique that enhances Raman scattering by molecules adsorbed on rough metal surfaces. It is known that metal nanoparticles, especially gold and silver nanoparticles, exhibit great SERS properties, which make them very attractive for the development of biosensors and biocatalysts. On the other hand, the development of ecofriendly methods for the synthesis of metallic nanostructures has become the focus of research in several countries, and many microorganisms and plants have already been used to biosynthesize metallic nanostructures. However, the majority of these are pathogenic to plants or humans. Here, we report gold nanoparticles with good SERS properties, biosynthesized by Neurospora crassa extract under different environmental conditions, increasing Raman signals up to 40 times using methylene blue as a target molecule. Incubation of tetrachloroauric acid solution with the fungal extract at 60°C and a pH value of a) 3, b) 5.5, and c) 10 resulted in the formation of gold nanoparticles of a) different shapes like triangles, hexagons, pentagons etc. in a broad size range of about 10-200 nm, b) mostly quasi-spheres with some different shapes in a main size range of 6-23 nm, and c) only quasi-spheres of 3-12 nm. Analyses included TEM, HRTEM, and EDS in order to corroborate the shape and the elemental character of the gold nanoparticles, respectively. The results presented here show that these 'green' synthesized gold nanoparticles might have potential applicability in the field of biological sensing.

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