Morphological, Photoluminescence, and Electrical Measurements of Rare-Earth Metal-Doped Cadmium Sulfide Thin Films.

This work is aimed at investigating the viability of utilizing cadmium sulfide (CdS) as a buffer layer in CdTe solar cells by analyzing and assessing its optical, photoluminescence, morphological, and electrical properties. These films were fabricated using a thermal coating technique. Optical microscopy was used to observe the changes in morphology resulting from the doping of rare-earth metals such as samarium (Sm) and lanthanum (La) to CdS, while the granular-like structure of the sample was confirmed by scanning electron microscopy. The objective of incorporating Sm and La ions into CdS was to enhance photoconductivity and optimize the optical bandgap, aiming to create a viable charge transport material for photovoltaic devices with enhanced efficiency. Through that process, a noticeable decrease in transmission, from approximately 80 to 68% in the visible region, was observed. Additionally, the bandgap value was reduced from 2.43 to 2.27 eV. Furthermore, during the analysis of the photoluminescence spectra, it was observed that emission peaks occurred in the visible region. These emissions were attributed to electronic transitions that took place via band-to-band and band-to-impurity interactions. The electrical measurements showed an enhancement in conductivity due to the decrease in the bandgap. This notable consequence of the doped materials suggests their utilization in photovoltaic systems.

Role of Citrullus colocynthis and Psidium guajava Mediated Green Synthesized Silver Nanoparticles in Disease Resistance against Aeromonas hydrophila Challenge in Labeo rohita.

Green synthesis of metallic nanoparticles is an auspicious method of preparing nanoparticles using plant extracts that have lesser toxicity to animal cells and the host. In the present work, we analyzed the antibacterial activity of Citrullus colocynthis and Psidium guajava-mediated silver nanoparticles (Cc-AgNPs and Pg-AgNPs, respectively) against Aeromonas hydrophila (A. hydrophila) in an in vivo assay employing Labeo rohita (L. rohita). L. rohita were divided into six groups for both Cc-AgNPs and Pg-AgNPs treatments separately: Control, A. hydrophila infected, A. hydrophila + Ampicillin, A. hydrophila + Cc/Pg-AgNPs (25 µg/L), A. hydrophila + Cc/Pg-AgNPs (50 µg/L), and A. hydrophila + Cc/Pg-AgNPs (75 µg/L). Changes in different bio-indicators such as hematological, histological, oxidative stress, and cytokine analysis were observed. Interestingly, the infected fish treated with both types of AgNPs (Cc-AgNPs and Pg-AgNPs) exhibited a higher survival rate than the untreated infected fish and demonstrated signs of recovery from the infection, providing a compelling indication of the positive impact of phytosynthesized AgNPs. Disruptions in hematological and histological parameters were found in the infected fish. Both Cc-AgNPs and Pg-AgNPs showed recovery on the hematological and histological parameters. Analysis of oxidative stress and cytokine markers also revealed provoking evidence of the positive impact of Cc-AgNPs and Pg-AgNPs treatment against disease progression in the infected fish. The major finding of the study was that the higher concentrations of the nanoparticles (50 µg/L in the case of Cc-AgNPs and 75 µg/L in the case of Pg-AgNPs) were more effective in fighting against disease. In conclusion, our work presents novel insights for the use of green-synthesized AgNPs as economic and innocuous antibacterial candidates in aquaculture.

In-Vivo Bactericidal Potential of Mangifera indica Mediated Silver Nanoparticles against Aeromonas hydrophila in Cirrhinus mrigala.

The present study reports the green synthesis of silver nanoparticles from leaves' extract of Mangifera indica (M. indica) and their antibacterial efficacy against Aeromonas hydrophila (A. hydrophila) in Cirrhinus mrigala (C. mrigala). The prepared M. indica mediated silver nanoparticles (Mi-AgNPs) were found to be polycrystalline in nature, spherical in shapes with average size of 62 ± 13 nm. C. mrigala (n = ±15/group) were divided into six groups i.e., G1: control, G2: A. hydrophila challenged, G3: A. hydrophila challenged + Mi-AgNPs (0.01 mg/L), G4: A. hydrophila challenged + Mi-AgNPs (0.05 mg/L), G5: A. hydrophila challenged + Mi-AgNPs (0.1 mg/L) and G6: A. hydrophila challenged + M. indica extract (0.1 mg/L). Serum biochemical, hematological, histological and oxidative biomarkers were evaluated after 15 days of treatment. The liver enzyme activities, serum proteins, hematological parameters and oxidative stress markers were found to be altered in the challenged fish but showed retrieval effects with Mi-AgNPs treatment. The histological analysis of liver, gills and kidney of the challenged fish also showed regaining effects following Mi-AgNPs treatment. A CFU assay from muscle tissue provided quantitative data that Mi-AgNPs can hinder the bacterial proliferation in challenged fish. The findings of this work suggest that M. indica based silver nanoparticles can be promising candidates for the control and treatment of microbial infections in aquaculture.

Citrullus colocynthis-Mediated Green Synthesis of Silver Nanoparticles and Their Antiproliferative Action against Breast Cancer Cells and Bactericidal Roles against Human Pathogens.

The present study investigated the biomedical potential of eco-friendly Citrullus colocynthis-mediated silver nanoparticles (Cc-AgNPs). The antibacterial efficacy of Cc-AgNPs was evaluated against two multidrug-resistant pathogenic bacterial strains, Escherichia coli and Pseudomonas aeruginosa. The antiproliferative and antilipidemic performance of the prepared particles was determined against the MCF7 cell line, a breast cancer cell line. The in vitro antibacterial assay revealed that Cc-AgNPs induced dose-dependent bactericidal activity, as a considerable increase in the zone of inhibition (ZOI) was noted at higher concentrations. Reduced proliferation, migration, spheroid size, and colony formation exhibited the substantial antiproliferative potential of Cc-AgNPs against MCF7 cells. Significant alterations in the expression of cell surface markers, apoptosis, and cell proliferation genes further confirmed the antiproliferative impact of Cc-AgNPs. Moreover, Cc-AgNPs exhibited antilipidemic activity by reducing cellular cholesterol and triglyceride levels and regulating key genes involved in lipogenesis. In conclusion, these results propose that Cc-AgNPs can be employed as a potent tool for future antibacterial and anticancer applications.

Biosynthesis and Characterizations of Silver Nanoparticles from Annona squamosa Leaf and Fruit Extracts for Size-Dependent Biomedical Applications.

Green synthesis differs in the way that the plant produces chemicals that act as reducing and stabilizing agents, and by adopting this green synthesis, we have synthesized silver nanoparticles (AgNPs) from the leaf and fruit extracts of Annona squamosa (also known as Sharifa), where these extracts have played an important role as reducing and capping agents. The nanoparticles were synthesized as the consequence of a reduction that happened between plant extracts and the precursor solution. The prepared AgNPs were then characterized using scanning electron microscopy, UV-Visible spectroscopy, and X-ray diffraction to study their morphology, optical response, and crystallinity. A single distinctive absorption peak of colloidal AgNPs samples was observed at 430 nm and 410 nm for leaf and fruit extract samples, having an optical bandgap of 2.97 eV and 2.88 eV, respectively, with a spherical shape having a diameter in the range of 35-90 nm and 15-50 nm, respectively, whilst XRD studies supported the FCC cubic structure of the mediated AgNPs. These green synthesized AgNPs have a wide variety of uses, particularly in the biomedical domain, where they have the potential to treat numerous diseases and are reported to be efficient against antibacterial, anti-cancer, and anti-diabetic activities.

Biosynthesis, characterization and anti-dengue vector activity of silver nanoparticles prepared from Azadirachta indica and Citrullus colocynthis.

We report here biosynthesis of silver nanoparticles (AgNPs) using aqueous extracts of (i) Azadirachta indica leaves and (ii) Citrullus colocynthis fruit and their larvicidal activity against Aedes aegypti. The UV-Vis spectroscopy absorption peaks occurred in the range of 412-416 nm for A. indica AgNPs and 416-431 nm for C. colocynthis AgNPs indicating the silver nature of prepared colloidal samples. The scanning electron microscopy examination revealed the spherical morphology of both types of NPs with average size of 17 ± 4 nm (A. indica AgNPs) and 26 ± 5 nm (C. colocynthis AgNPs). The X-ray diffraction pattern confirmed the face-centred cubic (FCC) structure with crystallite size of 11 ± 1 nm (A. indica AgNPs) and 15 ± 1 nm (C. colocynthis AgNPs) while characteristic peaks appearing in Fourier transform infrared spectroscopy analysis indicated the attachment of different biomolecules on AgNPs. The larvicidal activity at different concentrations of synthesized AgNPs (1-20 mg l-1) and extracts (0.5-1.5%) against Aedes aegypti was examined for 24 h. A concentration-dependent larvicidal potential of both types of AgNPs was observed. The LC50 values were found to be 0.3 and 1.25 mg l-1 for C. colocynthis AgNPs and A. indica AgNPs, respectively. However, both extracts did not exhibit any notable larvicidal activity.

Synthesis and characterization of silver nanoparticle-decorated cobalt nanocomposites (Co@AgNPs) and their density-dependent antibacterial activity.

Magnetic cores loaded with metallic nanoparticles can be promising nano-carriers for successful drug delivery at infectious sites. We report fabrication, characteristic analysis and in vitro antibacterial performance of nanocomposites comprising cobalt cores (Co-cores) functionalized with a varied concentration of silver nanoparticles (AgNPs). A two-step polyol process synchronized with the transmetalation reduction method was used. Co-cores were synthesized with cobalt acetate, and decoration of AgNPs was carried out with silver acetate. The density of AgNPs was varied by changing the amount of silver content as 0.01, 0.1 and 0.2 g in the synthesis solution. Both AgNPs and Co-cores were spherical having a size range of 30-80 nm and 200 nm to more than 1 µm, respectively, as determined by scanning electron microscopy. The metallic nature and face-centred cubic crystalline phase of prepared nanocomposites were confirmed by X-ray diffraction. Biocompatibility analysis confirmed high cell viability of MCF7 at low concentrations of tested particles. The antibacterial performance of nanocomposites (Co@AgNPs) against Escherichia coli and Bacillus subtilis was found to be AgNPs density-dependent, and nanocomposites with the highest AgNPs density exhibited the maximum bactericidal efficacy. We therefore propose that Co@AgNPs as effective drug containers for various biomedical applications.

A Comparative Assessment of Nanotoxicity Induced by Metal (Silver, Nickel) and Metal Oxide (Cobalt, Chromium) Nanoparticles in Labeo rohita.

In the present in vivo study, we provide a comparison of toxicological consequences induced by four different types of spherical nanoparticles (NPs)-silver nanoparticles (AgNPs, 40 ± 6 nm), nickel (NiNPs, 43 ± 6 nm), cobalt oxide (Co3O4NPs, 60 ± 6 nm), and chromium oxide (Cr3O4NPs, 50 ± 5 nm)-on freshwater fish Labeo rohita. Fish were exposed to NPs (25 mg/L) for 21 days. We observed a NPs type-dependent toxicity in fish. An altered behavior showing signs of stress and a substantial reduction in total leukocyte count was noticed in all NP-treated groups. A low total erythrocyte count in all NP-treated fish except for Co3O4NPs was discerned while a low survival rate in the case of Cr3O4NP-treated fish was observed. A significant decrease in growth and hemoglobin were noticed in NiNP- and Cr3O4NP-treated fish. A considerable total protein elevation was detected in NiNP-, Co3O4NP-, and Cr3O4NP-treated groups. An upgrading in albumin level was witnessed in Co3O4NP- and Cr3O4NP-treated groups while a high level of globulin was noted in NiNP- and Co3O4NP-exposed groups. In all NP-treated groups, a depleted activity of antioxidative enzymes and pathological lesions in liver and kidney were noticed.

Size- and Shape-Dependent Antibacterial Studies of Silver Nanoparticles Synthesized by Wet Chemical Routes.

Silver nanoparticles (AgNPs) of different shapes and sizes were prepared by solution-based chemical reduction routes. Silver nitrate was used as a precursor, tri-sodium citrate (TSC) and sodium borohydride as reducing agents, while polyvinylpyrrolidone (PVP) was used as a stabilizing agent. The morphology, size, and structural properties of obtained nanoparticles were characterized by scanning electron microscopy (SEM), UV-visible spectroscopy (UV-VIS), and X-ray diffraction (XRD) techniques. Spherical AgNPs, as depicted by SEM, were found to have diameters in the range of 15 to 90 nm while lengths of the edges of the triangular particles were about 150 nm. The characteristic surface plasmon resonance (SPR) peaks of different spherical silver colloids occurring in the wavelength range of 397 to 504 nm, whereas triangular particles showed two peaks, first at 392 nm and second at 789 nm as measured by UV-VIS. The XRD spectra of the prepared samples indicated the face-centered cubic crystalline structure of metallic AgNPs. The in vitro antibacterial properties of all synthesized AgNPs against two types of Gram-negative bacteria, Pseudomonas aeruginosa and Escherichia coli were examined by Kirby-Bauer disk diffusion susceptibility method. It was noticed that the smallest-sized spherical AgNPs demonstrated a better antibacterial activity against both bacterial strains as compared to the triangular and larger spherical shaped AgNPs.

A colloidal route to fabricate hierarchical sticky and non-sticky substrates.

We present a facile and inexpensive bottom-up colloidal route to prepare sticky superhydrophobic surfaces and non-sticky ones. Either spin coating to assemble silica microspheres into random multilayered arrays or irreversible adsorption of gold nanoparticles is used to manufacture substrates with a single length scale roughness. Hierarchical roughness with multiple length scales is achieved by decorating the silica spheres with gold nanoparticles. The surface chemistry of the silica surfaces is modified by the adsorption of fluoroalkylsilane self-assembled monolayers, while gold nanoparticles are hydrophobized by dodecanethiol. The wetting properties, both static and dynamic, of surfaces in relation to the morphology of the substrates are addressed. We demonstrate the role of hierarchy in the roughness in converting a sticky into a non-sticky superhydrophobic surface and discuss the results in terms of existing models describing wetting characteristics.

Novel, highly selective gold nanoparticle patterning on surfaces using pure water.

We present a simple, novel procedure to selectively deposit gold nanoparticles using pure water. It enables patterning of nanoparticle monolayers with a remarkably high degree of selectivity on flat as well as microstructured oxide surfaces. We demonstrate that water molecules form a thin "capping" layer on exposed thiol molecules within the mercaptan self-assembled layer. This reversible capping of water molecules locally "deactivates" the thiol groups, therewith inhibiting the binding of metallic gold nanoparticles to these specific areas. This amazing role of water molecules can be used as a tool to pattern flat as well as structured surfaces with gold nanoparticles.

Superhydrophobic surfaces by anomalous fluoroalkylsilane self-assembly on silica nanosphere arrays.

We present the self-assembled formation of nanosized PFDTS (1H,1H,2H,2H-perfluorodecyltrichlorosilane) features on multilayered silica sphere arrays. We reveal the importance of residual water within the microsphere multilayers during PFDTS deposition and discuss a possible mechanism for the formation of the siloxane nanostructures. The multiscaled roughness induced by these superstructures is shown to lead to superhydrophobic behavior. The role of PFDTS is twofold: it (i) lowers the surface energy and (ii) provides the essential roughness to achieve superhydrophobicity. Moreover, the absence of PFDTS nanostructures on monolayers or in the absence of water leads to considerably smaller contact angles thereby indicating the relevance of multiscaled roughness for superhydrophobicity.