Green Synthesis of Silver Nanoparticles Using Randia aculeata L. Cell Culture Extracts, Characterization, and Evaluation of Antibacterial and Antiproliferative Activity.

The demand for metallic nanoparticles synthesized using green methods has increased due to their various therapeutic and clinical applications, and plant biotechnology may be a potential resource facilitating sustainable methods of AgNPs synthesis. In this study, we evaluate the capacity of extracts from Randia aculeata cell suspension culture (CSC) in the synthesis of AgNPs at different pH values, and their activity against pathogenic bacteria and cancer cells was evaluated. Using aqueous CSC extracts, AgNPs were synthesized with 10% (w/v) of fresh biomass and AgNO3 (1 mM) at a ratio of 1:1 for 24 h of incubation and constant agitation. UV-vis analysis showed a high concentration of AgNPs as the pH increased, and TEM analysis showed polydisperse nanoparticles with sizes from 10 to 90 nm. Moreover, CSC extracts produce reducing agents such as phenolic compounds (162.2 ± 27.9 mg gallic acid equivalent/100 g biomass) and flavonoids (122.07 ± 8.2 mg quercetin equivalent/100 g biomass). Notably, AgNPs had strong activity against E. coli, S. pyogenes, P. aeruginosa, S. aureus, and S. typhimurium, mainly with AgNPs at pH 6 (MIC: 1.6 to 3.9 µg/mL). AgNPs at pH 6 and 10 had a high antiproliferative effect on cancer cells (IC50 < 5.7 µg/mL). Therefore, the use of cell suspension cultures may be a sustainable option for the green synthesis of AgNPs.

Analysis of the thermoelectrical performance of samples made of Coir Agricultural Wastes combined with MWCNT.

A biomaterial made of coir and Multi-Walled Carbon Nanotubes (MWCNTs) is presented which exhibits a relatively high-Temperature Coefficient of Resistance (TCR) and thermal insulation properties. Bolometers usually offer acceptable thermal isolation, electrical resistance, and high TCR. Fibers from agricultural waste materials such as coir has a synergistic effect as thermal insulating material and noise reducer. Based on it, powdered coir pills were used as pilot samples, as well as 2 other samples with different dispersions of MWCNTs, sodium dodecyl benzene sulfonate (SDBS) and polyvinylpyrrolidone (PVP) solution. The 3 kinds of samples were thermo-electrically characterized to determine their bolometric performance. Thermal conductivity of k = 0.045 W/m K was obtained by solving the Fourier's law substituting the data into the equation describing heat flux on the sample around room temperature. Results show that adding different concentrations of MWCNT to powdered coir will lead to films with lower electrical resistance, therefore the thermal conductivity increases while thermal resistance decreases. Finally, the bolometric performance shows a maximum peak with a relatively high TCR of - 40.4% at a temperature of 300.3 K, this synthesized material outperforms by almost 1 order of magnitude larger than commercial materials. Results in this work also indicate that it is possible to tune bolometric parameters of this kind of samples and to use them as thermal insulators in the construction industry, when building roofs and walls.

Gene expression profile involved in signaling and apoptosis of osteoblasts in contact with cellulose/MWCNTs scaffolds.

The aim of this work was to evaluate the expression profile of genes involved in signaling, intracellular and extracellular Ca+2 concentration and apoptosis pathways of osteoblasts in contact with a scaffold made of a composite of BCN/MWCNTs. Osteoblasts were cultivated on BCN, MWCNTs and their mixtures. Osteoblast RNA was extracted for sintering cDNA to amplify genes of interest by PCR; intra- and extracellular calcium (Ca2+) was also quantified. Regarding the genes that participate in the regulation paths (MAPK and NF-KB), it was found that only the expression of NF-KB was affected in all treatments. The expression of VEGFA increased, except in the treatment of high concentration of MWCNTs, where remained unchanged. The expression of genes Apaf-1 and Bcl-2/Bax and TP53 increased as compared to the control (except for TP53 in BC and C1/MWCNTs) indicating that cells are responding to the presence of BCN-MWCNTs composites scaffolds. The results suggest that osteoblast developed a modification in the expression profile of genes that actively participate in cellular processes such as proliferation, vasculogenesis and apoptosis, which may be modulated by the increase of intra- and extracellular Ca2+ concentration.

In vitro evaluation of osteoblastic cells on bacterial cellulose modified with multi-walled carbon nanotubes as scaffold for bone regeneration.

In this paper we explore the use of native bacterial cellulose (BC) in combination with functionalized multi-walled carbon nanotubes (MWNTs) as an original biomaterial, suitable three-dimensional (3D) scaffold for osteoblastic cell culture. Functionalized MWNTs were mixed with native BC (secreted by Gluconacetobacter xylinus) with the aim of reinforcing the mechanical properties of BC. The results indicate that BC-MWNTs scaffolds support osteoblast viability, adhesion and proliferation at higher levels as compared to traditional culture substrates. Chemically functionalized MWNTs are also an excellent material to be used as scaffold because these did not affect cell viability and showed an enhanced osteoblast adhesion. These results suggest the potential for this combination of biomaterials, i.e. BC and carbon nanomaterials, as scaffolds for bone regeneration.

Use of Agave tequilana-lignin and zinc oxide nanoparticles for skin photoprotection.

The use of sunscreens is essential for preventing skin damage and the potential appearance of skin cancer in humans. Inorganic active components such as zinc oxide (ZnO) have been used commonly in sunscreens due to their ability to block UVA radiation. This ultraviolet (UV) protection might be enhanced to cover the UVB and UVC bands when combined with other components such as titanium dioxide (TiO2). In this work we evaluate the photoprotection properties of organic nanoparticles made from lignin in combination with ZnO nanoparticles as active ingredients for sunscreens. Lignin nanoparticles were synthesized from Agave tequilana lignin. Two different pulping methods were used for dissolving lignin from agave bagasse. ZnO nanoparticles were synthesized by the precipitation method. All nanoparticles were characterized by SEM, UV-Vis and FT-IR spectroscopy. Nanoparticles were mixed with a neutral vehicle in different concentrations and in-vitro sun protection factor (SPF) values were calculated. Different sizes of spherical lignin nanoparticles were obtained from the spent liquors of two different pulping methods. ZnO nanoparticles resulted with a flake shape. The mixture of all components gave SPF values in a range between 4 and 13. Lignin nanoparticles showed absorption in the UVB and UVC regions which can enhance the SPF value of sunscreens composed only of zinc oxide nanoparticles. Lignin nanoparticles have the added advantage of being of organic nature and its brown color can be used to match the skin tone of the person using it.

Silver nanoparticles induce anti-proliferative effects on airway smooth muscle cells. Role of nitric oxide and muscarinic receptor signaling pathway.

Silver nanoparticles (AgNPs) are used to manufacture materials with new properties and functions. However, little is known about their toxic or beneficial effects on human health, especially in the respiratory system, where its smooth muscle (ASM) regulates the airway contractility by different mediators, such as acetylcholine (ACh) and nitric oxide (NO). The aim of this study was to evaluate the effects of AgNPs on ASM cells. Exposure to AgNPs induced ACh-independent expression of the inducible nitric oxide synthase (iNOS) at 100 µg/mL, associated with excessive production of NO. AgNPs induced the muscarinic receptor activation, since its blockage with atropine and blockage of its downstream signaling pathway inhibited the NO production. AgNPs at 10 and 100 µg/mL induced ACh-independent prolonged cytotoxicity and decreased cellular proliferation mediated by the muscarinic receptor-iNOS pathway. However, the concentration of 100 µg/mL of AgNPs induced muscarinic receptor-independent apoptosis, suggesting the activation of multiple pathways. These data indicate that AgNPs induce prolonged cytotoxic and anti-proliferative effects on ASM cells, suggesting an activation of the muscarinic receptor-iNOS pathway. Further investigation is required to understand the full mechanisms of action of AgNPs on ASM under specific biological conditions.