Green synthesis and characterization of zinc oxide nanoparticles using bush tea (Athrixia phylicoides DC) natural extract: assessment of the synthesis process.

Background: Nanoparticles are globally synthesized for their antimicrobial, anti-inflammatory, wound healing, catalytic, magnetic, optical, and electronic properties that have put them at the forefront of a wide variety of studies. Among them, zinc oxide (ZnO) has received much consideration due to its technological and medicinal applications. In this study, we report on the synthesis process of ZnO nanoparticles using Athrixia phylicoides DC natural extract as a reducing agent. Methods: Liquid chromatography–mass spectrometry (LC-MS) was used to identify the compounds responsible for the synthesis of ZnO nanoparticles. Structural, morphological and optical properties of the synthesized nanoparticles have been characterized through X-ray diffraction (XRD), Ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Results: LC-MS results showed that different flavonoids and polyphenols, as well as Coumarin, an aromatic compound, reacted with the precursor to form ZnO nanoparticles. XRD and UV-Vis analysis confirmed the synthesis of ZnO nanoparticles, with a spherical shape showed in SEM images. The quasi-spherical ZnO crystals had an average crystallite size of 24 nm. EDS and FTIR analysis confirmed that the powders were pure with no other phase or impurity. Conclusions: This study successfully demonstrated that the natural plant extract of A. phylicoides DC. can be used in the bio-reduction of zinc nitrate hexahydrate to prepare pure ZnO nanoparticles, thus, extending the use of this plant to an industrial level.

Antiviral Activities of High Energy E-Beam Induced Copper Nanoparticles against H1N1 Influenza Virus

The pandemic outbreak of COVID-19 in the year of 2020 that drastically changed everyone’s life has raised the urgent and intense need for the development of more efficacious antiviral material. This study was designed to develop copper nanoparticles (Cu NPs) as an antiviral agent and to validate the antiviral activities of developed copper NP. The Cu NPs were synthesized using a high energy electron beam, and the characteristic morphologies and antiviral activities of Cu NPs were evaluated. We found that Cu NPs are of spherical shape and uniformly distributed, with a diameter of around 100 nm, as opposed to the irregular shape of commercially available copper microparticles (Cu MPs). An X-ray diffraction analysis showed the presence of Cu and no copper oxide II and I in the Cu NPs. A virus inactivation assay revealed no visible viral DNA after 10- and 30-min treatment of H1N1 virus with the Cu NPs. The infectivity of the Cu NPs-treated H1N1 virus significantly decreased compared with that of the Cu MPs-treated H1N1 virus. The viability of A549 bronchial and Madin-Darby Canine Kidney (MDCK) cells infected with Cu NPs-treated H1N1 was significantly higher than those infected with Cu MPs-treated H1N1 virus. We also found cells infected with Cu NPs-treated H1N1 virus exhibited a markedly decreased presence of virus nucleoprotein (NuP), an influenza virus-specific structural protein, compared with cells infected with Cu MPs-treated H1N1 virus. Taken together, our study shows that Cu NPs are a more effective and efficacious antiviral agent compared with Cu MPs and offer promising opportunities for the prevention of devastatingly infectious diseases.

Formulation, Characterization, and Cytotoxicity Evaluation of Lactoferrin Functionalized Lipid Nanoparticles for Riluzole Delivery to the Brain

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with a very poor prognosis. Its treatment is hindered by a lack of new therapeutic alternatives and the existence of the blood–brain barrier (BBB), which restricts the access of drugs commonly used in ALS, such as riluzole, to the brain. To overcome these limitations and increase brain targeting, riluzole-loaded nanostructured lipid carriers (NLC) were prepared and functionalized with lactoferrin (Lf), facilitating transport across the BBB by interacting with Lf receptors expressed in the brain endothelium. NLC were characterized with respect to their physicochemical properties (size, zeta potential, polydispersity index) as well as their stability, encapsulation efficiency, morphology, in vitro release profile, and biocompatibility. Moreover, crystallinity and melting behavior were assessed by DSC and PXRD. Nanoparticles exhibited initial mean diameters between 180 and 220 nm and a polydispersity index below 0.3, indicating a narrow size distribution. NLC remained stable over at least 3 months. Riluzole encapsulation efficiency was very high, around 94–98%. FTIR and protein quantification studies confirmed the conjugation of Lf on the surface of the nanocarriers, with TEM images showing that the functionalized NLC presented a smooth surface and uniform spherical shape. An MTT assay revealed that the nanocarriers developed in this study did not cause a substantial reduction in the viability of NSC-34 and hCMEC/D3 cells at a riluzole concentration up to 10 μM, being therefore biocompatible. The results suggest that Lf-functionalized NLC are a suitable and promising delivery system to target riluzole to the brain.

Characterization and biodistribution of trans resveratrol-PEG-folic acid-gold nanoparticle conjugates

Purpose: To evaluate the characteristics and biodistribution of trans resveratrol-PEG-folic acid-gold nanoparticle conjugates (rsv-PEG-FA-AuNP). Methods: Gold nanoparticles were produced by citric reduction followed by conjugation of PEG-folic acid and resveratrol. Characterization of rsv-PEG-FA-AuNP conjugates including their particle size, zeta potential, and by Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) was carried out. Biodistribution study of rsv-PEG-FA-AuNP was carried out using female Sprague Dawley rats. Biodistribution data were obtained from high performance liquid chromatography (HPLC) analysis. Results: The mean particle size and zeta potential of rsv-PEG-FA-AuNP were 249.03 ± 10.31 and - 36.33 ± 3.12 mV, respectively. TEM images showed rsv-PEG-FA-AuNP conjugates formed spherical shape. Rsv-PEG-FA-AuNP conjugates found in plasma, kidney (1.90 ± 0.20 μg/g), spleen (2.65 ± 1.18 μg/g), liver (1.74 ± 0.03 μg/g), and lung (1.82 ± 0.12 μg/g), after 90 minutes intravenous administration (i.v.) in female Sprague Dawley rats. No free resveratrol was found in plasma, kidney, or spleen after i.v administration in female dawdle Sprague Dawley rats. Conclusion: Resveratrol-PEG-FA-AuNP conjugates appear to be a potential chemotherapy delivery system for active targeting purposes because of its longer systemic circulation and its accumulation in the kidney.

Hydrodynamic and heat transfer analysis of dissimilar shaped nanoparticles-based hybrid nanofluids in a rotating frame with convective boundary condition

Solar thermal systems have low efficiency due to the working fluid's weak thermophysical characteristics. Thermo-physical characteristics of base fluid depend on particle concentration, diameter, and shapes. To assess a nanofluid's thermal performance in a solar collector, it is important to first understand the thermophysical changes that occur when nanoparticles are introduced to the base fluid. The aim of this study is, therefore, to analyze the hydrodynamic and heat characteristics of two different water-based hybrid nanofluids (used as a solar energy absorber) with varied particle shapes in a porous medium. As the heat transfer surface is exposed to the surrounding environment, the convective boundary condition is employed. Additionally, the flow of nanoliquid between two plates (in parallel) is observed influenced by velocity slip, non-uniform heat source-sink, linear thermal radiation. To make two targeted hybrid nanofluids, graphene is added as a cylindrical particle to water to make a nanofluid, and then silver is added as a platelet particle to the graphene/water nanofluid. For the second hybrid nanofluid, CuO spherical shape particles are introduced to the graphene/water nanofluid. The entropy of the system is also assessed. The Tiwari-Das nanofluid model is used. The translated mathematical formulations are then solved numerically. The physical and graphical behavior of significant parameters is studied.

Controlling Morphology and Functions of Cardiac Organoids by Two-Dimensional Geometrical Templates

Traditionally, tissue-specific organoids are generated as 3D aggregates of stem cells embedded in Matrigel or hydrogels, and the aggregates eventually end up a spherical shape and suspended in the matrix. Lack of geometrical control of organoid formation makes these spherical organoids limited for modeling the tissues with complex shapes. To address this challenge, we developed a new method to generate 3D spatial-organized cardiac organoids from 2D micropatterned hiPSC colonies, instead of directly from 3D stem cell aggregates. This new approach opens the possibility to create cardiac organoids that are templated by 2D non-spherical geometries, which potentially provides us a deeper understanding of biophysical controls on developmental organogenesis. Here, we designed 2D geometrical templates with quadrilateral shapes and pentagram shapes that had same total area but different geometrical shapes. Using this templated substrate, we grew cardiac organoids from human induced pluripotent stem cells (hiPSCs) and collected a series of parameters to characterize morphological and functional properties of the cardiac organoids. In quadrilateral templates, we found that increasing the aspect ratio impaired cardiac tissue 3D self-assembly, but the elongated geometry improved the cardiac contractile functions. However, in pentagram templates, cardiac organoid structure and function were optimized with a specific geometry of an ideal star shape. This study will shed a light on “organogenesis-by-design” by increasing the intricacy of starting templates from external geometrical cues to improve the organoid morphogenesis and functionality.

Facile and Eco-Friendly Fabrication of Silver Nanoparticles Using Nyctanthes arbor-tristis Leaf Extract to Study Antibiofilm and Anticancer Properties against Candida albicans

The synthesis of silver nanoparticles has been gaining more attention in recent years due to their small size and high stability. For this study, silver nanoparticles were biosynthesized from leaf extract of the medicinal plant (N. arbor-tristis). Vitally, the shrub with tremendous medicinal usage was diversely observed in South Asia and South East Asia. The synthesized silver nanoparticles were characterized by color visualization, ultraviolet-visible spectrophotometry (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), field emission-scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and dynamic light scattering (DLS) technique. A sharp peak at 427 nm for biosynthesized nanoparticles was obtained using UV-Vis, which represents surface plasmon resonance. Thus, characterization techniques showed the green synthesis of AgNPs leads to the fabrication of spherical shape particles with a size of 67 nm. Furthermore, AgNPs were subjected to antibiofilm studies against Candida albicans and it was observed that 0.5 μg mL−1 of AgNPs significantly reduced 50% of biofilm formation. These biosynthesized nanoparticles also showed a considerable reduction in viability of HeLa cells at 0.5 μg mL−1. The morphological changes induced by AgNPs were observed by AO/EB staining. The toxic effect of AgNPs was studied using brine shrimp as a model system. Therefore, it is envisaged that further investigation with these AgNPs can replace toxic chemicals, assist in the development of biomedical implants that can prevent biofilm formation, and avoid infections due to C. albicans.

CURCUMIN MICROENCAPSULATION USING CHITOSAN–ETHYL CELLULOSE–GMS MIXTURE FOR PRESERVATION OF MUCOADHESIVE PROPERTIES AND CONTROLLED RELEASE KINETIC

Objective: This research aimed to prepare curcumin microcapsules by the spray drying method and to evaluate their characteristics. Methods: The microcapsules were prepared by the spray drying method. The generated microcapsules were evaluated for organoleptic, morphology, particle size, the percentage of curcumin and water content. Furthermore, the release of curcumin from the microcapsules was tested in vitro and compared to uncoated curcumin powder. In addition, the mucoadhesive properties of uncoated curcumin powder and curcumin microcapsules were also evaluated. Results: The results showed that the microcapsules had spherical shape with particle size in the range of 100–1009 µm and water content of 9.34% (w/w) (FIII) and 8.09% (w/w) (FVI). The release of curcumin from its uncoated powder and the microcapsules FVI within 8 h were 8.87% and 26.32% (w/w), respectively. It was found that the mucoadhesive properties of microcapsules FVI were better than those of FIII and uncoated curcumin powder. Microcapsules FVI rendered the cumulative amount of curcumin remaining on the intestinal mucosa of 55% (w/w) within 3 h. Conclusion: Accordingly, curcumin microcapsules generated by spray drying could be further formulated into various solid dosage forms for a better therapeutic effect.

Synthesis and Characterization of Sulfur and Sulfur-Selenium Nanoparticles Loaded on Reduced Graphene Oxide and Their Antibacterial Activity against Gram-Positive Pathogens

Resistance to antimicrobial agents in Gram-positive bacteria has become a major concern in the last decade. Recently, nanoparticles (NP) have emerged as a potential solution to antibiotic resistance. We synthesized three reduced graphene oxide (rGO) nanoparticles, namely rGO, rGO-S, and rGO-S/Se, and characterized them using X-ray diffraction (PXRD), Raman analysis, and thermogravimetric analysis. Transmission electron microscopy confirmed spherical shape nanometer size S and S/Se NPs on the rGO surface. Antibacterial properties of all three nanomaterials were probed against Gram-positive pathogens Staphylococcus aureus and Enterococcus faecalis, using turbidometeric and CFU assays. Among the synthesized nanomaterials, rGO-S/Se exhibited relatively strong antibacterial activity against both Gram-positive microorganism tested in a concentration dependent manner (growth inhibition >90% at 200 μg/mL). Atomic force microscopy of rGO-S/Se treated cells displayed morphological aberrations. Our studies also revealed that rGO composite NPs are able to deposit on the bacterial cell surface, resulting in membrane perturbation and oxidative stress. Taken together, our results suggest a possible three-pronged approach of bacterial cytotoxicity by these graphene-based materials.

Influence of Cooling Scenarios on the Evolution of Microstructures in Nickel-Based Single Crystal Superalloys

The reprecipitation and evolution of γ’ precipitates during various cooling approaches from supersolvus temperature are studied experimentally and via phase field simulation in nickel-based single crystal superalloys. The focus of this paper is to explore the influence of cooling methods on the evolution of the morphology and the distribution of γ’ precipitates. It is demonstrated that small and uniform spherical shape γ’ particles formed with air cooling method. When the average cooling rate decreases, the particle number decreases while the average matrix and precipitate channel widths increase. The shape of γ’ precipitates which changed from spherical to cubic and irregular characteristics due to the elastic interaction and elements diffusion are observed with the decrease of the average cooling rate. The phase field simulation results are in good agreement with the experimental results in this paper. The research is a benefit for the study of the rejuvenation heat treatment in re-service nickel-based superalloys.