Biogeneration of silver nanoparticles from Cuphea procumbens for biomedical and environmental applications.

Nanotechnology is one of the most important and relevant disciplines today due to the specific electrical, optical, magnetic, chemical, mechanical and biomedical properties of nanoparticles. In the present study we demonstrate the efficacy of Cuphea procumbens to biogenerate silver nanoparticles (AgNPs) with antibacterial and antitumor activity. These nanoparticles were synthesized using the aqueous extract of C. procumbens as reducing agent and silver nitrate as oxidizing agent. The Transmission Electron Microscopy demonstrated that the biogenic AgNPs were predominantly quasi-spherical with an average particle size of 23.45 nm. The surface plasmonic resonance was analyzed by ultraviolet visible spectroscopy (UV-Vis) observing a maximum absorption band at 441 nm and Infrared Spectroscopy (FT IR) was used in order to structurally identify the functional groups of some compounds involved in the formation of nanoparticles. The AgNPs demonstrated to have antibacterial activity against the pathogenic bacteria Escherichia coli and Staphylococcus aureus, identifying the maximum zone of inhibition at the concentration of 0.225 and 0.158 µg/mL respectively. Moreover, compared to the extract, AgNPs exhibited better antitumor activity and higher therapeutic index (TI) against several tumor cell lines such as human breast carcinoma MCF-7 (IC50 of 2.56 µg/mL, TI of 27.65 µg/mL), MDA-MB-468 (IC50 of 2.25 µg/mL, TI of 31.53 µg/mL), human colon carcinoma HCT-116 (IC50 of 1.38 µg/mL, TI of 51.07 µg/mL) and melanoma A-375 (IC50 of 6.51 µg/mL, TI of 10.89 µg/mL). This fact is of great since it will reduce the side effects derived from the treatment. In addition, AgNPs revealed to have a photocatalytic activity of the dyes congo red (10-3 M) in 5 min and malachite green (10-3 M) in 7 min. Additionally, the degradation percentages were obtained, which were 86.61% for congo red and 82.11% for malachite green. Overall, our results demonstrated for the first time that C. procumbens biogenerated nanoparticles are excellent candidates for several biomedical and environmental applications.

Remineralizing Effect of Xilitol, Juniperus Communis and Camellia Sinensis Added to a Toothpaste: An In Vitro Study / Efecto remineralizante del Xilitol, Juniperus Communis y Camellia Sinensis adicionados en pastas dentales: Estudio in vitro

ABSTRACT The aim of this study was to explore the remineralizing effect of toothpastes based on Xilitol, Camellia Sinensis and Juniperus Communis. An in vitro experimental study was carried out in an 18 human premolars sample, which were treated with one of the 3 evaluated toothpastes and a control fluoride one. The atomic percentages of Ca and P were evaluated by Energy Dispersive X-ray Spectroscopy (EDS). In addition, the enamel surface of treated teeth was visualized by Scanning Electron Microscopy (SEM). The evaluations were carried out in three stages: pre-treatment, after an artificial demineralization process and after the treatment with the toothpastes. In the statistical analysis, the one-way ANOVA and Pearson correlation tests were used. Xilitol and Juniperus Communis showed the greatest gain of P ions compared to the control group (p<0.01). As for Ca, the group treated with xylitol-based toothpaste showed more ion gain compared with the control group (p<0.01). In the Pearson correlation test between Ca and P, statistically significant correlations were observed in all groups (p<0.01), ranging between r=0.7413 (Xylitol Group) and r=0.9510 (Control Group). We concluded that Xylitol paste showed the highest remineralizing property, both in the EDS analysis and in the SEM images.

RESUMEN El objetivo de este studio fue explorer el efecto remineralizante de las cremas dentales compuestas de Xilitol, Camelia Sinensis y Juniperus Communis. Se llevó a cabo un estudio experimental in vitro en una muestra de 18 premolares humanos, los cuales fueron tratados con una de las tres pastas dentales evaluadas y una fluorada. Los porcentajes atomicos de Ca y P fueron evaluados por Espectroscopia de rayos X de energía dispersive (EDS). Además, la superficie del esmalte de los dientes tratados fue examinada por Microscopia Electronica de Barrido (SEM). Las evaluaciones fueron llevadas a cabo en tres etapas: pre-tratamiento, despues de un proceso artificial de desmineralizacion y después del tratamiento con las pastas dentales. Se usaron ANOVA de una via y correlacion de Pearson para el analisis estadistico. Xilitol y Juniperus Communis mostraron la mayor ganancia de iones P comparados con el grupo control (p<0.01), con rangos entre r=0.7413 (Grupo con Xylitol) and r=0.9510 (Group Control). Se concluyó que la pasta con Xilitol mostró las mayores propiedades remineralizantes, tanto en el analisis EDS y las imágenes SEM.

Biosynthesis of Silver Nanoparticles on Orthodontic Elastomeric Modules: Evaluation of Mechanical and Antibacterial Properties.

In the present study, silver nanoparticles (AgNPs) were synthesized in situ on orthodontic elastomeric modules (OEM) using silver nitrate salts as metal-ion precursors and extract of the plant Hetheroteca inuloides (H. inuloides) as bioreductant via a simple and eco-friendly method. The synthesized AgNPs were characterized by UV-visible spectroscopy; scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). The surface plasmon resonance peak found at 472 nm confirmed the formation of AgNPs. SEM and TEM images reveal that the particles are quasi-spherical. The EDS analysis of the AgNPs confirmed the presence of elemental silver. The antibacterial properties of OEM with AgNPs were evaluated against the clinical isolates Streptococcus mutans, Lactobacillus casei, Staphylococcus aureus and Escherichia coli using agar diffusion tests. The physical properties were evaluated by a universal testing machine. OEM with AgNPs had shown inhibition halos for all microorganisms in comparison with OEM control. Physical properties increased with respect to the control group. The results suggest the potential of the material to combat dental biofilm and in turn decrease the incidence of demineralization in dental enamel, ensuring their performance in patients with orthodontic treatment.

Synthesis of silver nanoparticles using aqueous extracts of Heterotheca inuloides as reducing agent and natural fibers as templates: Agave lechuguilla and silk.

Silver nanoparticles (Ag NPs) were synthesized using a one-pot green methodology with aqueous extract of Heterotheca inuloides as a reducing agent, and the support of natural fibers: Agave lechuguilla and silk. UV-Vis spectroscopy, X-Ray photoelectron spectroscopy XPS and transmission electron microscopy TEM were used to characterize the resulting bionanocomposite fibers. The average size of the Ag NPs was 16nm and they exhibited low polydispersity. XPS studies revealed the presence of only metallic Ag in the nanoparticles embedded in Agave. lechuguilla fibers. Significant antibacterial activities against gram-negative Escherichia coli and gram-positive Staphylococcus aureus were determined. AgO as well as metallic Ag phases were detected when silk threads were used as a substrates hinting at the active role of substrate during the nucleation and growth of Ag NPs. These bionanocomposites have excellent mechanical properties in tension which in addition to the antibacterial properties indicate the potential use of these modified natural fibers in surgical and biomedical applications.