Bio-inspired Synthesis of Metal and Metal Oxide Nanoparticles: The Key Role of Phytochemicals

A novel approach for synthesizing silver nanoparticles with antibacterial and cytotoxic activities using the leaf extract of hydroponically grown Moringa oleifera

Novel approaches for producing silver nanoparticles (Ag-NPs), which are widely used in biomedicine, biotechnology, and agriculture, are of considerable importance. This study highlights a simple and cost-effective biological method for the synthesis of Ag-NPs using the leaf extract of the hydroponically cultivated Moringa oleifera (MOAg-NPs), alongside the analysis of the biosynthesized NPs. One of the advantages of hydroponic cultivation over traditional soil-based methods is that plants are cleaner since they are not in contact with soil and can be cultivated with fewer chemical inputs. For characterization of the biosynthesized MOAg-NPs various methods have been used, such as UV-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), X-Ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. UV-Vis analysis revealed a prominent peak at 465 nm, indicating the synthesis of MOAg-NPs. TEM analysis demonstrated a spherical shape of MOAg-NPs with an average diameter of 10.0 ± 6.0 nm. The XRD pattern displayed Ag peaks at 2θ values corresponding to (111), (200), (220) and (311) reflections. The antibacterial efficacy of MOAg-NPs was assessed against Gram-positive (Enterococcus hirae, Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli), revealing their antibacterial potential at low concentrations. The general inhibitory mechanism of MOAg-NPs focuses on the energy-dependent total and N, N'-dicyclohexylcarbodiimide (DCCD)-sensitive H+-fluxes across the bacterial membrane. Moreover, the application of MOAg-NPs resulted in substantial inhibition of HeLa cells growth. Thus, Ag-NPs synthesized using hydroponically grown M. oleifera leaf extract exhibited cytotoxicity against cancer cells and antibacterial properties, highlighting their potential use in biomedicine.

Comparative photocatalytic performance of iron nanoparticles biosynthesized from aqueous extracts of potato, potato peels, and leaves

This study presents an eco-friendly, cost-effective approach for synthesizing highly efficient nanocatalysts with the help of organic waste. Iron nanoparticles (INPs) were synthesized from aqueous extracts of potato, potato peel, and potato leaf and were evaluated for their photocatalytic efficiency for the degradation of methylene blue dye. X-ray Diffraction (XRD) confirmed Fe3O4 nanoparticles cubic crystal structure with the smallest crystallite size (9.52 nm) with potato peel, and Brunauer-Emmett-Teller (BET) analysis also showed the highest surface area (61.2 m2/g) for the same material. At the same time, other characterizations such as Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and Ultraviolet-Visible Spectroscopy (UV-Vis) for these nanoparticles were also performed, which provided insights into the chemical and physical composition and photoactivity. Photocatalytic tests demonstrated efficient methylene blue (MB) degradation under sunlight for all iron nanoparticles. The iron nanoparticle prepared using potato peel extracts achieved the highest degradation efficiency of 99 % in 120 min, with the highest first-order kinetics K = 0.0426 min-1, attributed to its smallest crystallite size, highest surface area, and suitable band gap.

Facile microwave-assisted green synthesis and characterization of flower shaped zinc oxide nanoclusters using Centella asiatica (Linn.) leaf extract and evaluation of its antimicrobial activity and in vivo toxic effects on Artemia nauplii

Green synthesized nanomaterials play a vital role in nanotechnology was due to its diverse applications. In the current study, flower shaped nanoclusters of zinc oxide nanoparticles (ZnONPs) was fabricated using the leaf extract of Centella asiatica (Linn.) by microwave-assisted method. The physico-chemical characterization of the green synthesized ZnONPs were further conducted by the UV-Vis spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and transmission electron microscopy analysis. The UV-Vis spectrum of the synthesized ZnONPs has showed characteristic absorption maximum at 363 nm. The XRD pattern of the same could confirm to have the crystalline nature of ZnONPs. Additionally, the FT-IR spectra have revealed the presence of characteristic stretching and bending vibrations of the Zn-O bond, along with those of phytochemicals that might have involved in ZnONPs stabilization. By the HR-TEM imaging, agglomeration of the nanoparticles and thereby the formation of flower-like clusters could be observed. Furthermore, the synthesized ZnONPs have remarkable antimicrobial activity against S. aureus and E. coli with inhibition zones of 15 ± 0.4 and 16.5 ± 1.0 mm respectively. The green synthesized ZnONPs showed no significant toxicity toward Artemia nauplii. Hence, the results of the study indicate the promising potential of the synthesized ZnO nanoclusters.

Recent advances and challenges of the green ZnO-based composites biosynthesized using plant extracts for water treatment

Recently, there has been a notable rise in the prevalence of persistent pollutants in the environment, posing a significant hazard due to their toxicity and enduring nature. Conventional wastewater treatment methods employed in treatment plants rarely address these persistent pollutants adequately. Meanwhile, the concept of green synthesis has garnered considerable attention, owing to its environmentally friendly approach that utilizes fewer toxic chemicals and solvents. The utilization of materials derived from sustainable sources presents a promising avenue for solving pressing environmental concerns. Among the various sources of biological agents, plants stand out for their accessibility, eco-friendliness, and rich reserves of phytochemicals suitable for material synthesis. The plant extract-mediated synthesis of zinc oxide nanoparticles (ZnONPs) has emerged as a promising solution for applications in wastewater treatment. Thorough investigations into the factors influencing the properties of these green ZnONPs are essential to establish a detailed and reliable synthesis process. Major weaknesses inherent in ZnONPs can be addressed by changing the optical, magnetic, and interface properties through doping with various semiconductor materials. Consequently, research efforts to mitigate water pollution are being driven by both the future prospects and limitations of ZnO-based composites. This review underscores the recent advancements of plant extract-mediated ZnONP composites for water treatment.

Potential nanomedicinal applications and physicochemical nature of Hyphaene thebaica-reduced nano-samaria

Herein we described the biofabrication of samarium oxide nanoparticles (HT-Sm2O3 NPs) by applying the aqueous fruit extract of Hyphaene thebaica was utilized as an eco-friendly chelating agent. The prepared NPs were subjected to various physicochemical properties and potential in biomedical applications. X-ray Diffraction (XRD) pattern revealed sharp peaks that corroborated with the Joint Committee on Powder Diffraction Standards (JCPDS) card no. 00-042-1464. Crystallite size obtained from Debye-Scherrer approximation and Williamson-Hall (W-H) plot was 28.73 and 69.3 nm, respectively. Optical bandgap was calculated by employing Kubelka-Munk (K-M) function and was found to be ~4.58 eV. Raman shift was observed at 121, 351, 424-, and 561 cm-1. Photoluminescence (PL) spectra revealed two major peaks positioned at 360 and 540 nm. The high-resolution transmission electron microscopy (HR-TEM) analysis of HT-Sm2O3 nanoparticles (NPs) showed that they predominantly have spherical to cuboidal shapes. Additionally, the selected area electron diffraction (SAED) pattern presented spotty rings, indicating a high level of crystallinity in these NPs. The potential nanomedicine applications were studied using diverse bioassays using different treatments. The antioxidant activity demonstrated 45.71% ± 1.13% inhibition at 1000 μg/mL. Brine shrimp lethality assay revealed the highest cytotoxicity of 46.67% ± 3.33% at 1000 μg/mL and LC50 value of 1081 μg/mL. HT-Sm2O3 NPs exhibited inhibition of angiogenesis (20.41% ± 1.18%) at of 1000 μg/mL. MTT assay results indicated that HT-Sm2O3 NPs exhibit inhibitory effects on cell lines. Specifically, these NPs showed an IC50 value of 104.6 μg/mL against 3T3 cells. Against MCF-7 cells, the NPs demonstrated an IC50 value of 413.25 μg/mL. Additionally, in the inhibition of acetylcholinesterase (AChE), the newly synthesized NPs showed an IC50 value of 320 μg/mL. The antidiabetic assessment through α-glucosidase and α-amylase inhibition assays revealed, an IC50 value of 380 μg/mL for α-glucosidase and 952 μg/mL for α-amylase was calculated. Overall, our study suggested that the Sm2O3 NPs possess moderate anticancer, cholinesterase inhibition, and antidiabetic potential, however, needs further assessment. RESEARCH HIGHLIGHTS: In this work, nano-samaria is synthesized using an eco-friendly and green approach. The nanoparticles were characterized using techniques such as Raman, HR-TEM, FTIR, DRS, XRD, and so on, and the applications were studied using multiple in vitro bioassays for Diabetes, Alzheimer, and Cancer. The nano-samaria revealed good potential for potential biomedical applications.

Antidiabetic, anti-inflammatory, antioxidant, and cytotoxicity potentials of green-synthesized zinc oxide nanoparticles using the aqueous extract of Helichrysum cymosum

The current research involved the synthesis of zinc oxide nanoparticles (ZnO-NPs) using an aqueous extract of Helichrysum cymosum shoots, and subsequent characterization via different analytical methods, such as UV-Vis spectroscopy, Scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Transmission electron microscope (TEM), and zeta potential. The biological effects of the ZnO-NPs were then tested against C3A hepatocyte cells and L6 myocyte cell lines via series of analysis, including cytotoxicity, antioxidant, anti-inflammatory, and antidiabetic effect via enzymatic inhibition. The UV-Vis analysis showed a maximum absorption spectrum at 360, and the TEM analysis reveals a spherical and hexagonal structures, with an average dimension of 28.05-58.3 nm, and the XRD reveals a crystalline hexagonal structure. The zeta potential evaluation indicated that the ZnO-NPs are relatively stable at - 20 mV, and the FTIR analysis identified some important functional group associated with phenolics, carboxylic acid, and amides that are responsible for reducing and stabilizing the ZnO-NPs. The synthesized ZnO-NPs demonstrated cytotoxic effects on the cell lines at higher concentrations (125 µg/mL and 250 µg/mL), complicating the interpretation of the results of the inflammatory and antioxidant assays. However, there was a significant (p < 0.05) increase in the inhibitions of pancreatic lipase, alpha-glucosidase, and alpha-amylase, indicating beneficial antidiabetic effects.

Enhanced Efficacy of Some Antibiotics in the Presence of Silver Nanoparticles Against Clinical Isolate of Pseudomonas aeruginosa Recovered from Cystic Fibrosis Patients

Introduction

Given the increasing frequency of drug-resistant bacteria and the limited progress in developing new antibiotics, it is necessary to explore new methods of combating microbial infections. Nanoparticles, particularly silver nanoparticles (Ag-NPs), have shown exceptional antibacterial characteristics; however, elevated concentrations of Ag-NPs can produce noticeable levels of toxicity in mammalian cells.

Aim

This study examined the potential synergistic effect of combining a low dosage of Ag-NPs and anti-pseudomonas drugs against Pseudomonas aeruginosa (ATCC strain) and eleven clinical isolates from cystic fibrosis patients.

Methods

The Ag-NPs were chemically produced by utilizing a seed extract from Peganum Harmala and characterized via ultraviolet-visible spectroscopy and scanning electron microscopy. The broth microdilution technique was utilized to investigate the minimum inhibitory concentration (MIC) of Ag-NPs and eight antibiotics (Piperacillin, Ciprofloxacin, Levofloxacin, Meropenem, Amikacin, Ceftazidime, Gentamicin, Aztreonam). The fractional inhibitory concentration index (FICI) was determined via the checkerboard method to evaluate the synergistic effects of Ag-NPs and various antibiotics.

Results

The biosynthesized Ag-NPs were uniformly spherical and measured around 15 nm in size. When combined with antibiotics, Ag-NP produced statistically significant reductions in the amount of antibiotics required to completely prevent P. aeruginosa growth for all strains. The findings revealed that the MIC of Ag-NPs was 15 ug/mL for all strains which decreased substantially when administered with antibiotics at a dose of 1.875-7.5 ug/mL. The majority of Ag-NP and antibiotic combinations exhibited a synergistic or partially synergistic impact. This was particularly noticeable in combinations containing Meropenem, Ciprofloxacin, and Aztreonam (in which the FIC index was less than or equal to 0.5).

Conclusion

The findings revealed that combining Ag-NPs with antibiotics was more effective than using Ag-NPs or antibiotics in isolation and that combinations of Ag-NPs and antimicrobial agents displayed synergistic activity against the majority of strains assessed.

Rethinking Nanoparticle Synthesis: A Sustainable Approach vs. Traditional Methods

This review portrays a comparison between green protocols and conventional nanoparticle (NP) synthesis strategies, highlighting each method's advantages and limitations. Various top-down and bottom-up methods in NP synthesis are described in detail. The green chemistry principles are emphasized for designing safe processes for nanomaterial synthesis. Among the green biogenic sources plant extracts, vitamins, enzymes, polysaccharides, fungi (Molds and mushrooms), bacteria, yeast, algae, and lichens are discussed. Limitations in the reproducibility of green protocols in terms of availability of raw material, variation in synthetic protocol, and selection of material due to geographical differences are elaborated. Finally, a conclusion is drawn utilizing green chemical principles, & a circular economy strategy to minimize waste generation, offering a promising framework for the synthesis of NPs emphasizing sustainability.

Exploring the Potential of Nickel Oxide Nanoparticles Synthesized from Dictyota bartayresiana and its Biological Applications

The present study validates the impact of nickel oxide nanoparticles (NiONPs) biosynthesized from the brown seaweed Dictyota bartayresiana (DB) and its biological applications. The phytochemicals analyzed in the seaweed extract served as a reducing, capping or stabilizing agent in the formation of nanoparticles. UV visible spectrum of nickel oxide nanoparticles synthesized from DB (DB-NiONPs) represented a prominent peak at 392 nm which validates its formation. Fourier Transmission Infrared Spectroscopy (FT-IR) showcased the presence of functional groups in the biomolecules which aids in the stabilization of DB-NiONPs. The X-ray diffractometry (XRD) revealed the crystalline nature of DB-NiONPs and the particle size was calculated as 18.26 nm. The Scanning electron microscope (SEM) illustrates the irregularly shaped DB-NiONPs and the desired elements were depicted in energy dispersive X-ray (EDX) spectrum which confirms the purity of DB-NiONPs. The DB-NiONPs efficiently decolorised the Black B133 (BB133) dye to 86% in 25 min. The data of adsorption studies well fitted into Langmuir isotherm and pseudo-second order kinetic model. The thermodynamic study substantiated the spontaneous, feasible and endothermic process of adsorption. DB-NiONPs revealed enhanced antimicrobial, larvicidal and nematicidal activities against the selected microbes, larva of Culex pipens and juveniles of Meloidogyne incognita respectively. The phytotoxicity studies revealed the DB-NiONPs had a positive impact on the germination and growth of green gram seedlings.

Catharanthus roseus-assisted bio-fabricated zinc oxide nanoparticles for promising antibacterial potential against Klebsiella pneumoniae

This study emphasized on the synthesis of zinc oxide nanoparticles (ZnO NPs) in an environmentally friendly manner from the extract of Catharanthus roseus leaves and its antibacterial assessment against the pneumonia-causing pathogen Klebsiella pneumoniae. This simple and convenient phytosynthesis approach is found to be beneficial over conventional methods, wherein plants serve as excellent reducing, capping, and stabilizing agents that enables the formation of ZnO NPs without the use of harmful chemicals. The formation of ZnO NPs was confirmed through several characterization techniques such as UV-visible spectroscopy, XRD, FT-IR, SEM, HR-TEM, and EDX. XRD analysis revealed high polycrystallinity with crystallite size of approximately 13 nm. SEM and HR-TEM revealed the hexagonal structure of ZnO NPs with the particle size range of 20-50 nm. The EDX shows the elemental purity without any impurity. Furthermore, the antibacterial efficacy by the technique of disc diffusion exhibited clear inhibition zones in ZnO NPs-treated discs. In addition, 125 µg/mL of ZnO NP concentration showed minimum inhibition by the microbroth dilution method. The potent inhibitory activity was further validated with trypan blue dye exclusion and fluorescence microscopy. Finally, SEM examination confirmed the efficient antibacterial potential of ZnO NPs through disruption of the intact morphology of Klebsiella pneumoniae.

A Review of Plant-Mediated ZnO Nanoparticles for Photodegradation and Antibacterial Applications

This review focuses on the synthesis of plant-mediated zinc oxide nanoparticles (ZnO NPs) and their applications for antibacterial and photocatalytic degradation of dyes, thereby addressing the need for sustainable and eco-friendly methods for the preparation of NPs. Driven by the significant rise in antibiotic resistance and environmental pollution from dye pollution, there is a need for more effective antibacterial agents and photocatalysts. Therefore, this review explores the synthesis of plant-mediated ZnO NPs, and the influence of reaction parameters such as pH, annealing temperature, plant extract concentration, etc. Additionally, it also looks at the application of plant-mediated ZnO NPs for antibacterial and photodegradation of dyes, focusing on the influence of the properties of the plant-mediated ZnO NPs such as size, shape, and bandgap on the antibacterial and photocatalytic activity. The findings suggest that properties such as shape and size are influenced by reaction parameters and these properties also influence the antibacterial and photocatalytic activity of plant-mediated ZnO NPs. This review concludes that plant-mediated ZnO NPs have the potential to advance green and sustainable materials in antibacterial and photocatalysis applications.

MDSC-targeting gold nanoparticles enhance PD-1 tumor immunotherapy by inhibiting NLRP3 inflammasomes

Myeloid-derived suppressor cells (MDSCs) play a crucial role in the immune escape mechanisms that limit the efficacy of immunotherapeutic strategies. In the tumor microenvironment, NLRP3 inflammasome-driven Interleukin-1β (IL-1β) production serves to dampen antitumor immune responses, promoting tumor growth, progression, and immunosuppression. In this study, we revealed that gold nanoparticles (Au NPs) with a size of 30 nm disrupted NLRP3 inflammasome, but not other inflammasomes, in bone marrow-derived macrophages through abrogating NLRP3-NEK7 interactions mediated by reactive oxygen species (ROS). Density functional theory (DFT) calculations provided insights into the mechanism underlying the exceptional ROS scavenging capabilities of Au NPs. Additionally, when coupled with H6, a small peptide targeting MDSCs, Au NPs demonstrated the capacity to effectively reduce IL-1β levels and diminish the MDSCs population in tumor microenvironment, leading to enhanced T cell activation and increased immunotherapeutic efficacy in mouse tumor models that are sensitive and resistant to PD-1 inhibition. Our findings unraveled a novel approach wherein peptide-modified Au NPs relieved the suppressive impact of the tumor microenvironment by inhibiting MDSCs-mediated IL-1β release, which is the first time reported the employing a nanostrategy at modulating MDSCs to reverse the immunosuppressive microenvironment and may hold promise as a potential therapeutic agent for cancer immunotherapy.

Unleashing the promise of emerging nanomaterials as a sustainable platform to mitigate antimicrobial resistance

The emergence and spread of antibiotic-resistant (AR) bacterial strains and biofilm-associated diseases have heightened concerns about exploring alternative bactericidal methods. The WHO estimates that at least 700 000 deaths yearly are attributable to antimicrobial resistance, and that number could increase to 10 million annual deaths by 2050 if appropriate measures are not taken. Therefore, the increasing threat of AR bacteria and biofilm-related infections has created an urgent demand for scientific research to identify novel antimicrobial therapies. Nanomaterials (NMs) have emerged as a promising alternative due to their unique physicochemical properties, and ongoing research holds great promise for developing effective NMs-based treatments for bacterial and viral infections. This review aims to provide an in-depth analysis of NMs based mechanisms combat bacterial infections, particularly those caused by acquired antibiotic resistance. Furthermore, this review examines NMs design features and attributes that can be optimized to enhance their efficacy as antimicrobial agents. In addition, plant-based NMs have emerged as promising alternatives to traditional antibiotics for treating multidrug-resistant bacterial infections due to their reduced toxicity compared to other NMs. The potential of plant mediated NMs for preventing AR is also discussed. Overall, this review emphasizes the importance of understanding the properties and mechanisms of NMs for the development of effective strategies against antibiotic-resistant bacteria.

Refining shape and size of silver nanoparticles using ion irradiation for enhanced and homogeneous SERS activity

We present green synthesis of silver nanoparticles in water using unirradiated and Ag15 + ion irradiated phytoextracts of Bergenia Ciliata leaf, Eupatorium adenophorum leaf, Rhododendron arboreum leaf and flower. The use of different plant extracts and their subsequent ion irradiation allow for successful refinement of nanoparticle size and morphology. Due to changes in reducing and capping agents the nanoparticle surface functionalization also varies which not only controls the morphology but also allows for surface oxidation and aggregation processes. In this work, we have synthesized silver nanoparticles which exhibit sizes in the range from 13 to 24 nm and having shapes like spherical, quasispherical, trigonal, hexagonal, cylindrical, dendritic assemblies, and porous nanoparticles. Owing to changes in the size and shape of the nanoparticles, their direct bandgap (2.05 eV - 2.48 eV) and local surface plasmon resonance (420 nm - 490 nm) could also be tuned. These nanoparticles are examined as SERS substrates, where their enhancement factors, limit of detection for methylene blue, and SERS substrate homogeneity have been tested. It has been observed the nanoparticles synthesized using unirradiated plant extracts present an enhancement factor of 106 with a limit of detection 10- 8 M. Whereas nanoparticles with refined morphology and shapes upon irradiation present high enhancement factors of >107 and detection limit down to 10- 9 M. In addition, uniformity in Raman spectra over the SERS substrates has been obtained for selected Ag NPs substrates synthesized using irradiated extracts with minimum relative standard deviation in enhancement factor < 12%.

Plant‐mediated fabrication of cobalt oxide nanoparticles and evaluation of their catalytic effects on electro‐oxidation of formaldehyde

Cobalt oxide nanoparticles (Co3O4‐NPs) were synthesized by aqueous extract of Artemisia vulgaris plant at 50°C. The biosynthesized extract mediated Co3O4‐NPs were characterized through different methods containing FT‐IR (Fourier transform infrared spectroscopy), FESEM (Field emission scanning electron microscopy), EDS (Energy‐dispersive x‐ray spectroscopy), and XRD (x‐ray diffraction). Co3O4‐NPs as an efficient and practical catalyst was employed for the electrochemical oxidation of formaldehyde; which was an irreversible charge transfer controlled by mass transfer. The coefficients of electron transfer and diffusion were 0.87 and 0.122 cm2/s for formaldehyde oxidation on Co3O4 electrode, respectively. The formation of the CoOOH species during potential sweeping appears to be involved in the catalytic activity of the Co3O4 toward formaldehyde oxidation.

Magnesium oxide nanoparticles alleviate arsenic toxicity, reduce oxidative stress and arsenic accumulation in rice (Oryza sativa L.)

Magnesium oxide nanoparticles (MgO NPs) have been attracted by the scientific community for their combating action against heavy metal stress in plants. However, their role towards the mitigation of arsenic (As) induced toxicity is still obscure. In the present study, MgO NPs were synthesized through the green route and assessed their efficacy towards the reduction of As accumulation and phytotoxicity in As-stressed rice cultivar MTU-1010 under laboratory conditions. Initially, rice seedlings were grown under separate and combined applications of As (10 mg/L) and MgO NPs (0, 10, 50, and 100 mg/L) and further analyzed plant growth attributes and As accumulation in rice seedlings. Characterization of biosynthesized MgO NPs by UV-Vis spectrophotometer, transmission electron microscopy (TEM), scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis showed the cubic in shape, and crystalline nature (73.10%) with average size ranges from 17-23 nm. The growth experiment showed a significant (p < 0.05) increase in seed germination, seedling growth, photosynthetic and other pigments content, and biomass accumulation in rice seedlings under the combined application of As (10 mg/L) and MgO NPs (50 mg/L) as compared to only As (10 mg/L) treatment. Additionally, As exposure resulted in declined primary metabolites such as soluble sugars and protein. However, the application of MgO NPs exhibited the alleviation of As toxicity through significant (p < 0.05) reduction of As accumulation by 34 and 53% in roots and 44 and 62% in shoots of rice seedlings under 50 and 100 mg/L MgO NPs supplementations, respectively and restored the accumulation of the primary metabolites. Furthermore, MgO NPs demonstrated the ability to scavenge reactive oxygen species (ROS) like hydrogen peroxide (H2O2) and superoxide anion (O2•-), through significant (p < 0.05) promotion of non-enzymatic (carotenoid, anthocyanin, flavonoid, and proline) and enzymatic (CAT, POD, and SOD) antioxidant defence under As stress. These findings highlighted the potential of green synthesized MgO NPs towards the mitigation of As contamination in rice plants. However, future study is necessary to unfold the actual mechanisms responsible for the protective effects of MgO NPs and to screen out the optimal dose to be used to formulate a potent nanofertilizer for sustainable rice production in metal-contaminated soils.

A Comprehensive Review on the Roles of Metals Mediating Insect-Microbial Pathogen Interactions

Insects and microbial pathogens are ubiquitous and play significant roles in various biological processes, while microbial pathogens are microscopic organisms that can cause diseases in multiple hosts. Insects and microbial pathogens engage in diverse interactions, leveraging each other's presence. Metals are crucial in shaping these interactions between insects and microbial pathogens. However, metals such as Fe, Cu, Zn, Co, Mo, and Ni are integral to various physiological processes in insects, including immune function and resistance against pathogens. Insects have evolved multiple mechanisms to take up, transport, and regulate metal concentrations to fight against pathogenic microbes and act as a vector to transport microbial pathogens to plants and cause various plant diseases. Hence, it is paramount to inhibit insect-microbe interaction to control pathogen transfer from one plant to another or carry pathogens from other sources. This review aims to succinate the role of metals in the interactions between insects and microbial pathogens. It summarizes the significance of metals in the physiology, immune response, and competition for metals between insects, microbial pathogens, and plants. The scope of this review covers these imperative metals and their acquisition, storage, and regulation mechanisms in insect and microbial pathogens. The paper will discuss various scientific studies and sources, including molecular and biochemical studies and genetic and genomic analysis.

Heavy Metals, Their Phytotoxicity, and the Role of Phenolic Antioxidants in Plant Stress Responses with Focus on Cadmium: Review

The current state of heavy metal (HM) environmental pollution problems was considered in the review: the effects of HMs on the vital activity of plants and the functioning of their antioxidant system, including phenolic antioxidants. The latter performs an important function in the distribution and binding of metals, as well as HM detoxification in the plant organism. Much attention was focused on cadmium (Cd) ions as one of the most toxic elements for plants. The data on the accumulation of HMs, including Cd in the soil, the entry into plants, and the effect on their various physiological and biochemical processes (photosynthesis, respiration, transpiration, and water regime) were analyzed. Some aspects of HMs, including Cd, inactivation in plant tissues, and cell compartments, are considered, as well as the functioning of various metabolic pathways at the stage of the stress reaction of plant cells under the action of pollutants. The data on the effect of HMs on the antioxidant system of plants, the accumulation of low molecular weight phenolic bioantioxidants, and their role as ligand inactivators were summarized. The issues of polyphenol biosynthesis regulation under cadmium stress were considered. Understanding the physiological and biochemical role of low molecular antioxidants of phenolic nature under metal-induced stress is important in assessing the effect/aftereffect of Cd on various plant objects-the producers of these secondary metabolites are widely used for the health saving of the world's population. This review reflects the latest achievements in the field of studying the influence of HMs, including Cd, on various physiological and biochemical processes of the plant organism and enriches our knowledge about the multifunctional role of polyphenols, as one of the most common secondary metabolites, in the formation of plant resistance and adaptation.

Potential use of bio functionalized nanoparticles to attenuate triple negative breast cancer (MDA-MB-231 cells)

This study showed that bio-functional silver nanoparticles (AgNPs) and zinc oxide nanoparticles (ZnONPs) were synthesized in aqueous extracts of Gymnema sylvestre leaves and tested for toxicity assessment against triple-negative breast cancer cells (TNBC). Biofunctional nanoparticle (NPs) samples were characterized using UV-Vis spectroscopy, FT-IR, XRD, SEM, and TEM. The results showed that the phytofabrication of AgNPs resulted in a dark brown, UV-vis maximum absorbance peak at 413 nm. The AgNPs were crystalline and spherical, with sizes ranging from 20 to 60 nm, as confirmed by the XRD pattern and TEM images. Another phytofabrication of ZnONPs exhibited a white precipitate corresponding to a UV-Vis maximum absorption peak at 377 nm and a fine micro flower morphology with a particle-sized tribution between 100 and 200 nm. In addition, FT-IR spectra showed that bioorganic compounds are associated with NPs that respond to reduced Ag⁺ ions and AgNPs tabilizers. Invitro cytotoxicity studies revealed the potent anti-cancer effects of phytofabricated AgNPs and ZnONPs on TNBC cells. Furthermore, the AO/EB double staining assay results proved that apoptotic cells are distinguished by greenish-yellow fluorescence of the cell nuclei with IC₅₀ concentrations of 44 ± 0.8 µg/mL for AgNPs and 26.2 ± 0.5 µg/mL for ZnONPs, respectively. Based on our results, we expect that the anticancer function of the biofunctional NPs is due to the apoptotic activation of TNBC cells by increased ROS. Therefore, the presented study demonstrated that biofunctional AgNPs and ZnONPs have excellent prospects for the anti-cancer activity that can be used in pharmaceutical and medical fields.

Biosynthesis and characterization of iron oxide nanoparticles from Mentha spicata and screening its combating potential against Phytophthora infestans

Plant pathogens cause serious diseases to agricultural crops which lead to food insecurity in the world. To combat plant pathogens, various strategies have been developed including the use of agrochemicals. The overuse of these chemicals is now leading to the pesticide-resistant capability of pathogens. To overcome this problem, modern nanobiotechnology offers the production of alternative nano drugs. In this study, we used Mentha spicata for the synthesis of iron oxide nanoparticles using the green synthesis method. The synthesis of Fe2O3 NPs was confirmed through various characterizations. UV-Vis analysis detected a characteristic absorbance at the spectral range of 272 nm. The SEM micrographic analysis at various magnifications displayed circular or rod-shaped nanoparticles with a size ranging from 21 to 82 nm. The elemental EDX characterization showed intense peaks with a weight percent of 57, 34.93, and 8.07 for Fe, O, and, Cl respectively. TGA analysis showed that weight loss at 44-182, 500, and 660°C with no further modification indicates the thermal stability of iron oxide nanoparticles. FTIR spectrum of uncalined detects various bands at 3331, 1625, and 1,437 cm-1 for the hydroxyl group. After calcination two bands at 527 and 434 cm-1 were observed for Fe-O. The antimicrobial in vitro study showed maximum growth inhibition of Phytophthora infestans by the concentration of 100 μg ml-1 of Fe2O3-PE and Fe2O3 NPs. Therefore, this study resulted that bio-stable iron oxide nanoparticles can be used as alternative antimicrobial agents.