Resistance to antileishmanial drugs such as sodium stibogluconate (SSG), amphotericin B (Amp-B), and miltefosine is on the rise, and alternate strategies for effective treatment have gained importance in recent years. Although nanoparticle (NP)based composite drugs that have emerged recently have been found to be effective, the associated toxicity limits their usage. Bimetallic NPs produced through reduction with medicinal plant extracts are proposed to overcome the toxicity of the NPs. In the present study, three types of gold−silver bimetallic nanoparticles (Au−Ag BNPs) were synthesized through a single-step reduction process using fenugreek, coriander, and soybean leaf extracts. All of the three types of BNPs exhibited high antileishmanial effects against promastigotes with half-inhibitory concentration (IC 50 ) values in the range of 0.03−0.035 μg/mL. The IC 50 values of the BNPs are much lower compared to those of miltefosine (IC 50 = 10 μg/mL). The synthesized BNPs induced the reactive oxygen species (ROS)mediated apoptosis-like death in the promastigotes and could potentiate the antileishmanial activity of macrophages. The intracellular amastigotes were reduced by 31−46% in macrophages. The biogenic BNPs synthesized in this study and their potent antileishmanial activity provide further impetus to the ongoing quest for novel drugs to effectively manage leishmaniasis.
The glasses of the composition 20CaF2–xAl2O3–(59−x)P2O5–20SiO2:1.0Ho2O3/1.0Er2O3 and 20CaF2–xAl2O3–(59−x)P2O5–20SiO2:(0.6Ho2O3+0.4Er2O3) with x varying from 2 to 10 mol % have been synthesized. Optical absorption and fluorescence spectra (in the spectral range 350–2100 nm were studied at ambient temperature. The Judd–Ofelt theory was applied to characterize the absorption and luminescence spectra of Ho3+ and Er3+ ions in these glasses. Following the luminescence spectra, various radiative properties like transition probability A, branching ratio β, and the radiative life time τ for blue (B), green (G), and red (R) emission levels of these glasses have been evaluated. The radiative life times for these transitions of Ho3+ and Er3+ have also been measured. The variations observed in these parameters were discussed in the light of varying coordinations (tetrahedral and octahedral positions) of Al3+ ions in the glass network. The energy transfer between the two rare earth ions (Ho3+ and Er3+) in codoped CaF2–Al2O3–P2O5–SiO2 glass system in the visible and near infrared (NIR) regions has also been investigated as a function of varying concentration of Al2O3. A significant enhancement in the intensities of B, G, and R lines has been observed due to codoping. The quantitative analysis of these results (with the aid of the data on IR and Raman spectral studies) has indicated that the glasses mixed with around 6.0 mol % of Al2O3 is the optimum concentration for yielding the highest quantum efficiency and for maximum energy transfer with low phonon losses.
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