Eco-Friendly Synthesis and Comparative In Vitro Biological Evaluation of Silver Nanoparticles Using Tagetes erecta Flower Extracts

The present study reports an eco-friendly synthesis method of silver nanoparticles (AgNPs) using two different extracts (aqueous and ethanolic) of Tagetes erecta flowers. When exposed to different biocompounds found in the plant, silver ions are reduced, thus, resulting in the green synthesis of nanoparticles. After performing the optimization of synthesis, the obtained AgNPs were characterized using various techniques. The UV–Vis spectrum of the synthesized nanoparticles showed maximum peaks at 410 and 420 nm. TEM analysis revealed that the particles were spherical with a size ranging from 10 to 15 nm, and EDX analysis confirmed the presence of silver metal. The average diameter value obtained through DLS analysis for the two types of AgNPs (obtained using aqueous and ethanolic extracts) was 104 and 123 nm. The Zeta potentials of the samples were −27.74 mV and −26.46 mV, respectively, which indicates the stability of the colloidal solution. The antioxidant and antimicrobial activities assays showed that nanoparticles obtained using the aqueous extract presented enhanced antioxidant activity compared to the corresponding extract, with both types of AgNPs exhibiting improved antifungal properties compared to the initial extracts.

De-novo fabrication of sunlight irradiated silver nanoparticles and their efficacy against E. coli and S. epidermidis

Silver nanoparticles (AgNPs) gained significant attention due to their activity against microbial pathogens, cancer cells, and viral particles etc. Traditional fabrication methods require hazardous chemicals as reducing agents and their usage and disposal pose a significant hazard to environmental ecosystem. Here, a de novo, robust, cost effective and an eco-friendly method is reported to fabricate AgNPs irradiated with sunlight (SL) while using Salvadora persica root extract (SPE) as reducing agent. Sunlight (SL) irradiated S. persica silver nanoparticles (SpNPs) i.e., SL-SpNPs were characterized using multiple techniques and their antibacterial efficacy was evaluated. The SL-SpNPs were synthesized in 10 min. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) analysis revealed their spherical morphology with a size range of 4.5–39.7 nm, while surface plasmon resonance (SPR) peaked at 425 nm. Fourier transform infrared spectroscopy (FTIR) analysis suggested that the reduction of SL-SpNPs was due to the presence of phytochemicals in the SPE. Furthermore, X-ray powder diffraction (P-XRD) pattern depicted the crystal structure of SL-SpNPs, hence proving the presence of AgNPs. Further the antibacterial studies were carried out against Escherichia coli (ATCC 11229) and Staphylococcus epidermidis (ATCC 12228) using Kirby Bauer method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for E. coli were determined to be 1.5 μg/mL and 3.0 μg/mL respectively while MIC and MBC values for S. epidermidis were found to be 12.5 μg/mL and 25 μg/mL respectively. The solar irradiation-based fabrication method and resulting SL-SpNPs can find their utility in many biomedical and environmental applications.

Preparation and Characterisation of Cellulose Nanocrystal/Alginate/Polyethylene Glycol Diacrylate (CNC/Alg/PEGDA) Hydrogel Using Double Network Crosslinking Technique for Bioprinting Application

In this study, we aimed to prepare and characterise hydrogel formulations using cellulose nanocrystals (CNCs), alginate (Alg), and polyethylene glycol diacrylate (PEGDA). The CNC/Alg/PEGDA formulations were formed using a double network crosslinking approach. Firstly, CNC was extracted from oil palm trunk, and the size and morphology of the CNCs were characterised using TEM analysis. Secondly, different formulations were prepared using CNCs, Alg, and PEGDA. The mixtures were crosslinked with Ca2+ ions and manually extruded using a syringe before being subjected to UV irradiation at 365 nm. The shear-thinning properties of the formulations were tested prior to any crosslinking, while the determination of storage and loss modulus was conducted post extrusion after the Ca2+ ion crosslink using a rheometer. For the analysis of swelling behaviour, the constructs treated with UV were immersed in PBS solution (pH 7.4) for 48 h. The morphology of the UV crosslinked construct was analysed using SEM imaging. The extracted CNC exhibited rod-like structures with an average diameter and length of around 7 ± 2.4 and 113 ± 20.7 nm, respectively. Almost all CNC/Alg/PEGDA formulations (pre-gel formulation) displayed shear-thinning behaviour with the power-law index η < 1, and the behaviour was more prominent in the 1% [w/v] Alg formulations. The CNC/Alg/PEGDA with 2.5% and 4% [w/v] Alg displayed a storage modulus dominance over loss modulus (G′ > G″) which suggests good shape fidelity. After the hydrogel constructs were subjected to UV treatment at 365 nm, only the F8 construct [4% CNC: 4% Alg: 40% PEGDA] demonstrated tough and flexible characteristics that possibly mimic the native articular cartilage property due to a similar water content percentage (79.5%). In addition, the small swelling ratio of 4.877 might contribute to a minimal change of the 3D construct’s geometry. The hydrogel revealed a rough and wavy surface, and the pore size ranged from 3 to 20 µm. Overall, the presence of CNCs in the double network hydrogel demonstrated importance and showed positive effects towards the fabrication of a potentially ideal 3D bioprinted scaffold.

Green Fabrication of Silver Nanoparticles using Euphorbia serpens Kunth Aqueous Extract, Their Characterization, and Investigation of Its In Vitro Antioxidative, Antimicrobial, Insecticidal, and Cytotoxic Activities

The silver nanoparticles (AgNPs) were synthesized via green synthesis approach using Euporbia serpens Kunth aqueous extract. The synthesized AgNPs were characterized by UV-visible spectroscopy and Furrier Transformer Infra-Red spectroscopy to justify the reduction and stabilization of AgNPs from its precursors. AgNPs characteristic absorption peak was observed at 420 nm in the UV-visible spectrum. The SEM and TEM analysis demonstrated the spherical shape of the synthesized nanoparticles with particle sizes ranging from 30 nm to 80 nm. FTIR transmission bands at 2920 cm-1, 1639 cm-1, 1410 cm-1, 3290 cm-1, and 1085 cm-1 were attributed to C-H, C=O, C-C, N-H, and C-N functional groups, respectively. XRD peaks could be attributed to (111), (200), (220), and (311) crystalline plane of the faced-centered cube (FCC) crystalline structure of the metallic silver nanoparticles. The AgNPs showed good antibacterial activity against all the tested bacteria at each concentration. The particles were found to be more active against Escherichia coli (E. coli) with 20 ± 06 mm and Salmonella typhi (S. typhi) with 18 ± 0.5 mm zone of inhibition in reference to standard antibiotic amoxicillin with 23 ± 0.3 mm and 20 ± 0.4 mm zone of inhibition, respectively. Moderate antifungal activities were observed against Candida albicans (C. albicans) and Alternaria alternata (A. alternata) with zone of inhibitions 16.5 mm and 15 mm, respectively, compared to the standard with 23 mm of inhibition. Insignificant antifungal inhibition of 7.5 mm was observed against Fusarium gramium (F. gramium). All the tested concentrations of AgNPs showed comparable % RSA with the standard reference ascorbic acid in the range sixty percent to seventy five percent. The percent motility at 3 hours postincubation showed quick response and most Tetramorium caespitum were found deceased or paralyzed. Similarly, the percent mortality showed a linear response at concentration and time. It was observed that 1 μg/mL to 2 μg/mL concentration of AgNPs displayed a significant cytotoxic activity against Artemia salina with LD50 of 5.37 and 5.82, respectively.

Effect of Formulation Variables for the Production of WGA-Grafted, Levodopa-Loaded PLGA Nanoparticles

Levodopa is used for the treatment of Parkinson’s disease (PD) for the last few decades. However, adverse reactions such as dyskinesia, somnolence, nausea, itching, rash, as well as the need for frequent dosing and low bioavailability problems affect the success of the treatment. To prevent side effects caused by conventional therapy, a nanoparticular drug delivery system has been developed, in which receptors are constantly stimulated, and the frequency of dosing is reduced. In this study, levodopa was loaded in Poly lactic-co-glycolic acid (PLGA) nanoparticles (NP) which modified with Wheat Germ Agglutinin (WGA) To increase the effectiveness of levodopa, reduce its side effects and apply to the nasal area which is an alternative way for brain targeting with lower doses. To obtain the optimum levodopa loaded PLGA nanoparticles, the effect of some formulation variables such as polyvinyl alcohol (PVA) concentration, homogenization speed, polymer amount and molecular weight, and levodopa content on the entrapment efficiency (EE) and particle size of the nanoparticles were investigated. Besides these variables, the effect of different parameters on the WGA binding constant was also searched. In addition to in vitro release studies, Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectrophotometer (FT-IR), and Transmission electron microscopy (TEM) analysis were used in the characterization of nanoparticles. Among all formulations, A2 and A8a which was produced with different molcular weights of PLGA, different added levodopa amounts and with different homogenization speeds were chosen as optimum formulations due to their sustained release properties and the ability to release 80 % of their drug content.WGA binding constant was found 78.20 % for A8a-1 and 95 % for A2-1. In this study, we aimed to determine the effect of different formulation parameters on the development of levodopa loaded and WGA grafted PLGA nanoparticles and on the quality characteristics of nanoparticle formulations such as particle size, zeta potential, and EE. In this paper, our results are demonstrated for a better understanding of the effect of process parameters on the development of nanoparticle-based drug delivery systems by using the double-emulsion solvent evaporation technique and on WGA binding of drug-loaded PLGA nanoparticles.

Sustainable synthesis of microwave-assisted IONPs using Spinacia oleracea L. for control of fungal wilt by modulating the defense system in tomato plants

Background Changing climate enhances the survival of pests and pathogens, which eventually affects crop yield and reduces its economic value. Novel approaches should be employed to ensure sustainable food security. Nano-based agri-chemicals provide a distinctive mechanism to increase productivity and manage phytopathogens, with minimal environmental distress. In vitro and in greenhouse studies were conducted to evaluate the potential of green-synthesized iron-oxide nanoparticles (IONPs) in suppressing wilt infection caused by Fusarium oxysporum f. sp. lycospersici, and improving tomato growth (Solanum lycopersicum) and fruit quality. Results Various microwave powers (100–1000 W) were used to modulate the properties of the green-synthesized IONPs, using spinach as a starting material. The IONPs stabilized with black coffee extract were substantively characterized using X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy, dielectric and impedance spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning and transmission electron microscopy (SEM and TEM, respectively), and magnetization analysis. XRD revealed a cubic magnetite (Fe3O4) phase with super-paramagnetic nature, detected at all microwave powers. The binding energies of Fe 2p3/2 (710.9 eV) and Fe 2p1/2 (724.5 eV) of Fe3O4 NPs were confirmed using XPS analysis at a microwave power of 1000 W. Uniform, spherical/cubical-shaped particles with an average diameter of 4 nm were confirmed using SEM and TEM analysis. A significant reduction in mycelial growth and spore germination was observed upon exposure to different IONP treatments. Malformed mycelium, DNA fragmentation, alternation in the cell membrane, and ROS production in F. oxysporum indicated the anti-microbial potential of the IONPs. The particles were applied both through the root (before transplantation) and by means of foliar application (after two weeks) to the infected seedlings. IONPs significantly reduced disease severity by an average of 47.8%, resulting in increased plant growth variables after exposure to 12.5 µg/mL of IONPs. Analysis of photosynthetic pigments, phenolic compounds, and anti-oxidant enzymes in the roots and shoots showed an increasing trend after exposure to various concentrations of IONPs. Correspondingly, lycopene, vitamin C, total flavonoids, and protein content were substantially improved in tomato fruits after treatment with IONPs. Conclusion The findings of the current investigation suggested that the synthesized IONPs display anti-fungal and nutritional properties that can help to manage Fusarium wilt disease, resulting in enhanced plant growth and fruit quality. Graphical Abstract

The Spectroscopic and Antimicrobial Yield of Sol-Gel Derived Zinc Copper Silicate/E102 Nanoclusters

The structural and optical properties of 30 ZnO: 50 SiO2: (20-x) CuO (ZSC) loaded with E102 (tartrazine dye) (where x=0.02, 0.05, 0.07 wt.%) nanoclusters have been explored. These nanoclusters were synthesized by a sol-gel route followed by a very controlled crystallization process at 500oC. The phase formation, structural modification, and particle distribution behavior of these nanoclusters have been studied using XRD and TEM analysis to monitor the domestic environment for ZCS-E102. The optical transmission and reflection properties of nanoclusters in the UV-Vis-NIR range were studied for the present nanoclusters from which the optical absorption was calculated. Tauc method is employed to estimate the type and value of energy needed to gap transition from absorption data. The direct and indirect gap shows decreased energy need for its transition by E102 concentration increase. The antimicrobial potentials of four synthesized nanoclusters were performed against some pathogenic microbes. The toxicity performance of all studied nanoclusters is measured. Results revealed that ZSC-0.07E102 is showed an effective antimicrobial action against four tested pathogenic microbes in terms of excellent inhibitory effect and biocompatibility show noticeable potential in the antimicrobial application. Therefore, this proficient nanomaterial is a promising choice for biomedical purposes.

Diazotization-azo coupling reaction of alphnaphthol over silica-sulfaric acid catalyst

Using agrowaste as a source of recycled materials is a hot topic among experts and technologists these days. Waste materials can be converted into energy and new products by using them. As a rice waste, rice husk (RH) is a rich source of pure silica that is recyclable. The pure silica in RH was sulfonated by agitating and reacting it with diluted sulfuric acid. Various sulfate concentrations were loaded on silica (5, 10, 15, and 20%), andthe catalyst was designated as RHASO4. As the sulfate content increased, the specific surface area decreased. TEM analysis showed different forms of catalyst, including spherical, cylindrical, and fibbered forms. The catalyst was used for the in-situ generation of nitrose acid to prepare a diazonium salt for aromatic coupling reactions. Our experiment indicates that azo dyes can be produced at 68 percent over the catalyst at 10 degrees Celsius, while traditional catalysts cannot produce them above 5 degrees Celsius. For the highest yield of azo dyes, a 20% sulfate loading is optimum. A simple laboratory procedure is followed to reuse a catalyst without deteriorating its properties.

Synthesis and in vitro drug release of primaquine phosphate loaded PLGA nanoparticles

Plasmodium falciparum is one of the most common resistant Plasmodium species responsible for high rates of morbidity and mortality in malaria patients. Clinical guidelines for the management of Plasmodium falciparum include the use of a dose of primaquine phosphate resulting intolerable side effects. Therefore, the aim of this work was to formulate primaquine phosphate-loaded PLGA nanoparticles by using a nanoprecipitation method in order to increase its bioavailability to minimize drug intake. This leads to reduced toxicity and better therapeutic efficacy of the drug. The synthesized nanoparticles were characterized by using dynamic light scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transformed infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and powder X-ray diffraction (XRD). TEM analysis revealed the presence of smooth spherical-shaped nanoparticles. The drug DLS analysis confirmed the presence of negatively charged nanoparticles with particle size in the range of 100-400 nm. The drug release study was performed to analyses different kinetic models like zero-order model, first-order model, Higuchi model, Hixson-Crowell model, and Korsmeyer-Peppas model.

Biosynthesis of Silver Chloride Nanoparticles by Rhizospheric Bacteria and Their Antibacterial Activity against Phytopathogenic Bacterium Ralstonia solanacearum

Ralstonia solanacearum is the most destructive pathogen, causing bacterial wilt disease of eggplant. The present study aimed to develop green synthesis and characterization of silver chloride nanoparticles (AgCl-NPs) by using a native bacterial strain and subsequent evaluation of their antibacterial activity against R. solanacearum. Here, a total of 10 bacterial strains were selected for the biosynthesis of AgCl-NPs. Among them, the highest yield occurred in the synthesis of AgCl-NPs using a cell-free aqueous filtrate of strain IMA13. Ultrastructural observation revealed that the AgCl-NPs were spherical and oval with smooth surfaces and 5–35 nm sizes. XRD analysis studies revealed that these particles contained face-centered cubic crystallites of metallic Ag and AgCl. Moreover, FTIR analysis showed the presence of capping proteins, carbohydrates, lipids, and lipopeptide compounds and crystalline structure of AgCl-NPs. On the basis of phylogenetic analysis using a combination of six gene sequences (16S, gyrA, rpoB, purH, polC, and groEL), we identified strain IMA13 as Bacillus mojavensis. Three kinds of lipopeptide compounds, namely, bacillomycin D, iturin, and fengycin, forming cell-free supernatant produced by strain IAM13, were identified by MALDI-TOF mass spectrometry. Biogenic AgCl-NPs showed substantial antibacterial activity against R. solanacearum at a concentration of 20 µg/mL−1. Motility assays showed that the AgCl-NPs significantly inhibited the swarming and swimming motility (61.4 and 55.8%) against R. solanacearum. Moreover, SEM and TEM analysis showed that direct interaction of AgCl-NPs with bacterial cells caused rupture of cell wall and cytoplasmic membranes, as well as leakage of nucleic acid materials, which ultimately resulted in the death of R. solanacearum. Overall, these findings will help in developing a promising nanopesticide against phytopathogen plant disease management.