Evaluation of antimicrobial activities of blue-green algae-mediated silver and gold nanoparticles

Pomegranate Rhizosphere Microbial Diversity Revealed by Metagenomics: Toward Organic Farming, Plant Growth Promotion and Biocontrol?

Food production must undergo systems change to meet the sustainable development goals (SDGs). For example, organic farming can be empowered by soil microorganisms with plant growth promotion (PGP) and biocontrol features. In this context, there have been limited studies on pomegranate. We investigated microbial diversity in rhizosphere of the pomegranate "Bhagwa" variety and its potential role in PGP and biocontrol. Both bulk and rhizosphere soil samples were analyzed for their physicochemical properties. Whole metagenome sequencing was conducted using the Illumina NovaSeq6000 platform. Surprisingly, we found that bulk and rhizosphere soil samples had comparable microbial diversity. Metagenome sequencing revealed the abundance of Streptomyces indicus, Bradyrhizobium kalamazoonesis, and Pseudomonas cellulosum in the rhizosphere that are reported here for the first time in agricultural literature. Pathway prediction analysis using KEGG (Kyoto Encyclopedia for Genes and Genomes) and COG (clusters of orthologous genes) databases identified metabolic pathways associated with biocontrol properties against pathogens. We confirmed the metagenome data in vitro, which demonstrated their PGP potential and antimicrobial properties. For instance, S. indicus produced high concentration of indole-3-acetic acid, a PGP phytohormone, that can stimulate plant growth. In addition, an antimicrobial susceptibility assay suggested that bacterial extracts displayed activity against Xanthomonas, a primary pathogen causing the pomegranate wilt disease. In conclusion, this study suggests that S. indicus, B. kalamazoonesis, and P. cellulosum can potentially be PGP and biocontrol agents that may contribute to increased crop productivity in pomegranate cultivation. These agents and their combinations warrant future research with an eye on SDGs and so as to enable and innovate organic farming and pomegranate agricultural practices.

Biogenic synthesis, characterization, and in vitro biological investigation of silver oxide nanoparticles (AgONPs) using Rhynchosia capitata

The current research aimed to study the green synthesis of silver oxide nanoparticles (AgONPs) using Rhynchosia capitata (RC) aqueous extract as a potent reducing and stabilizing agent. The obtained RC-AgONPs were characterized using UV, FT-IR, XRD, DLS, SEM, and EDX to investigate the morphology, size, and elemental composition. The size of the RC-AgONPs was found to be ~ 21.66 nm and an almost uniform distribution was executed by XRD analysis. In vitro studies were performed to reveal biological potential. The AgONPs exhibited efficient DPPH free radical scavenging potential (71.3%), reducing power (63.8 ± 1.77%), and total antioxidant capacity (88.5 ± 4.8%) to estimate their antioxidative power. Antibacterial and antifungal potentials were evaluated using the disc diffusion method against various bacterial and fungal strains, and the zones of inhibition (ZOI) were determined. A brine shrimp cytotoxicity assay was conducted to measure the cytotoxicity potential (LC50: 2.26 μg/mL). In addition, biocompatibility tests were performed to evaluate the biocompatible nature of RC-AgONPs using red blood cells, HEK, and VERO cell lines (< 200 μg/mL). An alpha-amylase inhibition assay was carried out with 67.6% inhibition. Moreover, In vitro, anticancer activity was performed against Hep-2 liver cancer cell lines, and an LC50 value of 45.94 μg/mL was achieved. Overall, the present study has demonstrated that the utilization of R. capitata extract for the biosynthesis of AgONPs offers a cost-effective, eco-friendly, and forthright alternative to traditional approaches for silver nanoparticle synthesis. The RC-AgONPs obtained exhibited significant bioactive properties, positioning them as promising candidates for diverse applications in the spheres of medicine and beyond.

Synthesis of silver and copper nanoparticle using Spirulina platensis and evaluation of their anticancer activity

The present research displays the green synthesis of stable silver nanoparticles (Ag-NPs) and copper oxide nanoparticles (CuO-NPs). The aqueous solution of Spirulina platensis (blue green algae) source was used as a reducing and capping agent and this study assessed the cytotoxicity of Ag- and CuO-NPs on three cancer cell cultures: A549 (lung cancer), HCT (human colon cancer), Hep2 (laryngeal carcinoma cancer) and normal cell (WISH). For NPs characterization, the UV/Vis spectroscopy was used where their formation and crystallinity were proven with λ max values for Ag- and CuO-NPs of 425 and 234 nm, respectively. According to X-ray diffraction and transmission electron microscopy (TEM), Ag-NPs were spherical in shape (size 2.23-14.68 nm) and CuO-NPs were small (size 3.75-12.4 nm). Zeta potential analysis showed the particles potential, which was recorded by -14.95 ± 4.31 mV for Ag-NPs and -21.63 ± 4.90 mV for CuO-NPs. After that, Ag- and CuO-NPs were assessed for anticancer properties against A549, HCT, Hep2 and WISH. IC50 of Ag-NPs recorded 15.67, 12.94, 3.8 and 10.44 µg/ml for WISH, A549, HCT and Hep2, respectively. IC50 for CuO-NPs was recorded as 32.64, 54.59, 3.98 and 20.56 µg/ml for WISH, A549, HCT and Hep2 cells, respectively. Safety limits for WISH and A549 were achieved 98.64% by 2.44 µg/ml and 83.43% by 4.88 µg/ml of Ag-NPs, and it was found to be 97.94% by 2.44 µg/ml against HCT, while that for Hep2 is 95.9% by 2.44 µg/ml. Concerning the anticancer effect of CuO-NPs, the safety limit was recorded as 88.70% by 2.44 and 98.48% by 4.88 µg/ml against WISH and A549, while HCT reached 89.92% by 2.44 µg/ml and Hep2 was 83.33% by 4.88 µg/ml. Green nanotechnology applications such as Ag-NPs and CuO-NPs have numerous benefits of ecofriendliness and compatibility for biomedical applications such as anticancer effects against cancer cells.

Mycosynthesis of selenium nanoparticles using Penicillium tardochrysogenum as a therapeutic agent and their combination with infrared irradiation against Ehrlich carcinoma

Over the past years, the assessment of myco-fabricated selenium nanoparticles (SeNPs) properties, is still in its infancy. Herein, we have highly stable myco-synthesized SeNPs using molecularly identified soil-isolated fungus; Penicillium tardochrysogenum OR059437; (PeSeNPs) were clarified via TEM, EDX, UV-Vis spectrophotometer, FTIR and zeta potential. The therapeutic efficacy profile will be determined, these crystalline PeSeNPs were examined for antioxidant, antimicrobial, MIC, and anticancer potentials, indicating that, PeSeNPs have antioxidant activity of (IC50, 109.11 μg/mL) using DPPH free radical scavenging assay. Also, PeSeNPs possess antimicrobial potential against Penicillium italicum RCMB 001,018 (1) IMI 193,019, Methicillin-Resistant Staphylococcus aureus (MRSA) ATCC 4330 and Porphyromonas gingivalis RCMB 022,001 (1) EMCC 1699; with I.Z. diameters and MIC; 16 ± 0.5 mm and MIC 500 µg/ml, 11.9 ± 0.6 mm, 500 µg/ml and 15.9±0.6 mm, 1000 µg/ml, respectively. Additionally, TEM micrographs were taken for P. italicum treated with PeSeNPs, demonstrating the destruction of hyphal membrane and internal organelles integrity, pores formation, and cell death. PeSeNP alone in vivo and combined with a near-infrared physiotherapy lamp with an energy intensity of 140 mW/cm2 showed a strong therapeutic effect against cancer cells. Thus, PeSeNPs represent anticancer agents and a suitable photothermal option for treating different kinds of cancer cells with lower toxicity and higher efficiency than normal cells. The combination therapy showed a very large and significant reduction in tumor volume, the tumor cells showed large necrosis, shrank, and disappeared. There was also improvement in liver ultrastructure, liver enzymes, and histology, as well as renal function, urea, and creatinine.

Investigation of in vitro antimicrobial, antioxidant and antiproliferative activities of Nostoc calcicola biosynthesized gold nanoparticles

The cyanobacteria are the promising candidate for synthesizing gold nanoparticles (AuNPs), due to their ability to accumulate heavy metals from the cellular environment and additionally contain varied bioactive compounds as reducing and stabilizing agents. This study describes the N2-fixing cyanobacterium Nostoc calcicola-mediated bioreduction of AuNPs and the inherent antimicrobial, antioxidant, and antiproliferative activities in vitro. Biosynthesized Nc-AuNPs were characterized by spectral characterization techniques. The formation of AuNPs was physically confirmed by the colour change from pale green to dark violet. The UV-Vis analysis, further, proved the reduction in Nc-AuNPs with the cyanobacterium and showed a spectral peak at 527 nm. FESEM-EDX images suggested the surface morphology of the NPs as spherical, cuboidal, and size between 20 and 140 nm. The antimicrobial studies of Nc-AuNPs were carried out by agar-well diffusion method and MIC values against five pathogenic bacterial and two fungal strains were noted. The AuNPs exhibited potential antimicrobial activity against h-pathogenic bacteria with inhibitory zones ranging at 11-18 mm; against fungi ranging at 13-17 mm. Significant antioxidant potentialities were explored by a DPPH assay with an IC50 value of 55.97 μg/ mL. Furthermore, in the anticancer efficacy assay, the Nc-AuNPs inhibited cellular proliferation in human breast adenocarcinoma and cervical cancer cell lines at IC50 concentration, 37.3 μg/ml, and 44.5 μg/ml, respectively. Conclusively, N. calcicola would be an excellent source for synthesizing stable colloidal AuNPs that had significant credibility as phycological (algal) nanomedicines as novel prodrugs with multiple bioactivities.

Biosynthesis and Characterization of Silver Nanoparticles Produced by Parachlorella kessleri and Cyclotella spp., and the Evaluation of Their Antibacterial Activity

Green synthesis is one of the fastest and best ways for ecofriendly nanoparticle synthesis. This study aims to investigate the use of the green microalgae Parachlorella kesseleri and Cyclotella spp. for the biological synthesis of silver nanoparticles (AgNPs). This work focuses on optimizing various parameters necessary for the production and stability of AgNPs. The nanoparticle formation was confirmed by UV-Visible analysis, which revealed the surface plasmon resonance band at 420 nm. The characterization of the AgNPs was performed using UV-visible spectroscopy, X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The antimicrobial properties of these bioactive AgNPs were also tested, showing excellent antibacterial activity against six bacterial strains, Escherichia coli, multidrug-resistant Escherichia coli, Bacillus clausii, Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella typhi. The biosynthesis of AgNPs from living cultures of microalgae has remarkable antibacterial properties. Other studies are underway in our laboratory to clarify the mechanism of the biosynthesis of these nanoparticles, and their action on bacteria.

Polycladia myrica-based delivery of selenium nanoparticles in combination with radiotherapy induces potent in vitro antiviral and in vivo anticancer activities against Ehrlich ascites tumor

Background: Over the last few decades, nanotechnology has entered daily life through various applications, therefore, there has been a trend toward developing new approaches to green-mediated nanotechnology that encourage nanomaterial formation through biological methods such as plants or microorganisms. Algae have gained increasing attention from nanotechnology scientists and have paved the way for the emergence of "algae nanotechnology" as a promising field. Methods: Via using the aqueous extract of the brown alga Polycladia myrica, selenium nanoparticles were synthesized and characterized by using seven instruments: SEM, TEM, UV spectra, Zeta potential, EDX, X-ray diffraction, and FTIR. P. myrica selenium nanoparticles (PoSeNPs) were then examined for their antiviral activity against HSV-1 (Herpes simplex I) and anticancer against human colon cancer cell line (HCT-116) in vitro and in vivo alone and in combination with laser therapy of power 2 mW against Ehrlich carcinoma (EAC). Results: PoSeNPs ranging between 17.48 nm and 23.01 nm in size, and EDX revealed the selenium mass and its atoms as 0.46% ± 0.07% and 0.08% ± 0.01% respectively. Their anticancer potentiality in vitro was with maximum inhibitions of 80.57% and 73% and IC₅₀ = 14.86 μg/mL and 50 mg/mL against HCT-116 and EAC cell lines respectively, while their in vivo alone and in combination with laser therapy of power 2 mW showed a potent therapy effect against Ehrlich ascites carcinoma (EAC). Conclusion: This study concluded that PoSeNPs do not have a toxic effect; they exhibit high effectiveness as a photothermal agent for cancer therapy, with promising applications in future biomedical fields. The combined therapy showed a significant decrease in tumor volume, massive tumor cell necrosis, shrinking, and disappearance. It also showed improvement in liver TEM, histology, kidney function: urea and creatinine, and liver enzymes: ALT, and AST.