Journal of Nanotechnology

Due to relatively low price and nontoxicity of photovoltaic (PV) systems, dye-sensitized solar cells (DSSCs) recently gained a lot of attention in terms of improving their performance and longevity. Because most of the major elements are impacted by their separate production and layering procedures, the substances in DSSCs are critical to achieving these goals. Methylene blue dye sensitizer-based solar cells were effectively constructed in this work, and DSSC performance was assessed. The morphologies of nanocrystalline CdS thin films were investigated by the FE-SEM machine, and then XRD patterns of 1 layer, 2 layers, and 3 layers of nanocrystalline CdS thin films were analyzed. The thicknesses of the prepared samples were about 391 nm, 457 nm, and 912 nm for 1, 2, and 3 layers of nanocrystalline CdS thin film, respectively. J-V characteristics of the multilayer CdS thin films have been studied under a 100 mW/cm² sunlight source. The experimental results revealed that the highest power conversion efficiency of a 3 layer porous-nanowall CdS/MB device was about 0.47%.

In this paper, we focus on the thermodynamics of redox reactions occurring during the vapor-liquid-solid (VLS) growth of silicon nanowires (NWs) with the participation of liquid solutions of metal catalysts. The growth of NWs is difficult with the participation of Ti, Al, and Mg particles; this is because in this case, the drops of the metal catalyst are strongly oxidized and crystals either do not form at all or are characterized by instability in the direction of growth. However, the particles of Cu, Ni, and Fe give a much more stable growth of NWs. We have also established that if the oxide film of catalytic particles is formed by the basic metal oxides, then the silicon-NWs' growth slows down. In this work, we have concluded that only metals with a lower chemical affinity for O₂ than Si are applicable as catalysts for the NWs' growth.

Ophthalmic drug delivery for treating various eye diseases still remains a challenge in ophthalmology. One perspective way of overcoming this problem is to use nanoscale biodegradable drug carriers that are able to safely deliver pharmaceuticals directly to the locus of disease and maintain a therapeutic concentration of drug for a long time. The goal of the present study was the preparation of drug- (dexamethasone-, DEX-) loaded pseudo-protein nanoparticles (NPs) and investigation of drug encapsulation efficiency and drug release kinetics. DEX-loaded pseudo-protein NPs (DEX-NPs) were successfully prepared by the nanoprecipitation method. DEX-NPs were characterized by size (average diameter, AD), size distribution (polydispersity index, PDI), and surface charge (zeta-potential, ZP) using the dynamic light scattering technique. DEX encapsulation characteristics were determined using the UV-spectrophotometric method, and kinetics of DEX release from DEX-NPs was studied according to the dialysis method in PBS at 37°C. The obtained results showed that size of DEX-NPs varies within 143.6–164.1 nm depending on DEX content during the preparation. DEX incorporation characteristics were determined—encapsulation efficiency (EE) and actual drug loading (DL) were high enough and reached 55.1 and 10.2%, respectively. The kinetics of DEX release from DEX-NPs showed a typical biphasic release pattern—an initial rapid (burst) release and further much more continuous slow release. Based on the obtained data, we can conclude that the elaborated DEX-NPs have potential for the application in ophthalmology as ocular drug delivery nanocarriers.

Superhydrophobic cotton fabric with photoinduced reversibly switchable wettability was prepared by a coating of the hydrophobic copolymer and α-Fe₂O₃ nanoparticles. The surface morphology of the fabric was observed by scanning electron microscope (SEM). The wettability of the surface was tested under UV illumination and after storage in the dark. The chemical composition of the cotton fabric surfaces before and after UV illumination was analyzed using an X-ray photoelectron spectroscope (XPS) and FTIR. The experimental results showed that the prepared cotton fabric exhibited the excellent superhydrophobic property with a contact angle (CA) of 157.3 ± 2.9°, and became superhydrophilic after UV illumination for 64 h. The surface wettability reverted back to its initial superhydrophobic state after being stored in the dark for 30 d. Based on the XPS and FTIR analyses, the possible mechanism was discussed, and the switchable wettability was caused by the content change of the hydroxyl groups on the α-Fe₂O₃ surface. Moreover, the superhydrophobic cotton fabric also became superhydrophilic after sunlight illumination for 120 h.

This study synthesized silver nanoparticles (Ag-NPs) using silver nitrate (AgNO₃) as the ion source and sodium tripolyphosphate (STPP) as reducing as well as capping agents. The synthesized Ag-NPs were confirmed initially using Ag-NPs specific λ_max at 410 nm with UV-Vis spectrophotometry and homogenously distributed, 100–300 nm size, and round-shaped particles were realized through atomic force microscopy (AFM) and transmission electron microscopy (TEM) image analysis. The various reaction condition-based studies revealed 0.01 M AgNO₃ yields maximum particle after 4 h reduction with 1% STPP. Bacillus spp. (n = 23/90) and Pseudomonas spp. (n = 26/90) were isolated from three different poultry farms for evaluating the antibacterial activity of Ag-NPs. Among the PCR confirmed isolates, 52% (12/23) Bacillus spp. were resistant to ten antibiotics and 65% (17/26) Pseudomonas spp. were resistant to eleven antibiotics. The representative resistant isolates were subjected to antibacterial evaluation of synthesized Ag-NPs following the well diffusion method, revealing the maximum sensitive zone of inhibition 19 ± 0.2 mm against Bacillus spp. and 17 ± 0.38 mm against Pseudomonas spp. The minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) of Ag-NPs were 2.1 μg/ml and 8.4 μg/ml, respectively, for broad-spectrum application. Finally, the biocompatibility was determined by observing the viability of Ag-NP-treated BHK-21 cell through trypan blue-based exclusion assay revealing nonsignificant decreased of cell viability ≤2MIC doses. Thus, the synthesized Ag-NPs were proven as biocompatible and sensitive to both Gram-positive and Gram-negative bacteria of the poultry farm environmental samples.

Hydroxyapatite nanoparticles (nHAPs) have been recognized for potent antitumor effects in certain cancer cells, making them good candidates as drug delivery agents and tumor therapeutics with fewer than normal side effects. This study is aimed to correlate cell proliferation inhibition with the size and morphology of nHAPs in a human breast cancer cell line as well as in normal tissue cells. We present our in vitro experimental evidence that nHAPs with sizes smaller than 50 nm have high inhibitory activity against human MCF-7 breast cancer cell lines. Based on our experimental data, normal fibroblast cells (NIH 3T3) were relatively more viable upon treatment with the nanoconstructs. The present study indicates that nHAPs can be engineered as nontoxic specific inhibitors as efficient breast cancer therapeutics in humans.