Evaluation of antibacterial activity of plant mediated CaO nanoparticles using C issus quadrangularis extract

In vitro safety profile and phyto-ecotoxicity assessment of the eco-friendly calcium oxide nanoparticles

The present study aims to evaluate the toxicity of the green calcium oxide nanoparticles (CaO-NPs) from golden linseed extract (Linum usitatissimum L.) by phytotoxicity in seeds (Daucus carota, Beet shankar, Lactuca sativa and Brassica oleracea), in vitro safety profile and soil toxicity for CaO-NPs solutions from 12.5 to 100 μg mL-1. Ecotoxicity analysis of the soil was conducted using XRD diffractograms, which revealed characteristic peaks of the nanoparticles at 37.35° (12.5, 25, 50, and 100 μg mL-1), as well as a peak at 67.34° (25 and 100 μg mL-1). Additionally, the in vitro safety assessment indicated favorable cell specification and regulation within the first 24 h, demonstrating reductions of 15.9 ± 0.2%, 17.9 ± 0.2%, 17.6 ± 0.2%, and 32.9 ± 0.2% to 12.5, 25, 50, and 100 μg mL-1, respectively. The dsDNA assay revealed initial protection and controlled release within the cells for 48 h. However, after 72 h, there was an increase of 20 ± 0.2%, 16 ± 0.2%, 32 ± 0.2%, and 43 ± 0.2% to 12.5, 25, and 50 μg mL-1. The analysis of ROS generation demonstrated a reduction of 40 ± 0.2%, 33 ± 0.2%, 20 ± 0.2%, and 9 ± 0.2% to 12.5, 25, 50, and 100 μg mL-1, respectively, within 72 h. When compared to the negative control (NC), there was an increase of 50 ± 0.2%, 56 ± 0.2%, 77 ± 0.2%, and 92 ± 0.2% at the same concentrations, suggesting that the nanoparticles generated free radicals, leading to cellular inflammation. This was attributed to the positive surface charge of the nanoparticles, resulting in reduced interaction with the cell membrane and the subsequent release of hydroxyl (•OH), which caused inflammatory processes in the cells. Therefore, CaO-NPs exhibited a low phytotoxicity and high cytocompatibility, while also promoting plant germination and growth.

Dietary anti-inflammatory and anti-bacterial medicinal plants and its compounds in bovine mastitis associated impact on human life

Bovine mastitis (BM) is the most common bacterial mediated inflammatory disease in the dairy cattle that causes huge economic loss to the dairy industry due to decreased milk quality and quantity. Milk is the essential food in the human diet, and rich in crucial nutrients that helps in lowering the risk of diseases like hypertension, cardiovascular diseases and type 2 diabetes. The main causative agents of the disease include various gram negative, and positive bacteria, along with other risk factors such as udder shape, age, genetic, and environmental factors also contributes much for the disease. Currently, antibiotics, immunotherapy, probiotics, dry cow, and lactation therapy are commonly recommended for BM. However, these treatments can only decrease the rise of new cases but can't eliminate the causative agents, and they also exhibit several limitations. Hence, there is an urgent need of a potential source that can generate a typical and ideal treatment to overcome the limitations and eliminate the pathogens. Among the various sources, medicinal plants and its derived products always play a significant role in drug discovery against several diseases. In addition, they are also known for its low toxicity and minimum resistance features. Therefore, plants and its compounds that possess anti-inflammatory and anti-bacterial properties can serve better in bovine mastitis. In addition, the plants that are serving as a food source and possessing pharmacological properties can act even better in bovine mastitis. Hence, in this evidence-based study, we particularly review the dietary medicinal plants and derived products that are proven for anti-inflammatory and anti-bacterial effects. Moreover, the role of each dietary plant and its compounds along with possible role in the management of bovine mastitis are delineated. In this way, this article serves as a standalone source for the researchers working in this area to help in the management of BM.

Efficient biogenesis of calcium oxide nanoparticles using the extract of Eleusine coracana seeds and their application against multidrug-resistant ocular bacterial pathogens

Visual impairment due to corneal keratitis-causing bacteria is becoming a matter of health concern. The bacterial colonization and their resistance to multiple drugs need imperative attention. To overcome the issue of alternative remedial therapeutic agents, particularly for topical application, a study was carried out to synthesize calcium oxide nanoparticles (CaO NPs) using the biomaterial Eleusine coracana seed aqueous extract. The biosynthesized calcium oxide nanoparticles (CaO NPs) are non-toxic or less-toxic chemical precursors. Moreover, CaO NPs are eco-friendly and are used for several industrial, biomedical, and environmental applications. Biosynthesized CaO NPs were characterized using ultraviolet-visible spectroscopy, Fourier transform-infrared spectroscopy, scanning electron microscopy, and dynamic light scattering study. The synthesized CaO NPs exhibit with good anti-inflammatory activities with dose dependant (50-250 μg/mL). Moreover, Eleusine coracana-mediated CaO NPs significantly inhibited the multiple drug-resistant Gram-positive Staphylococci epidermidis and Enterococcus faecalis and Gram-negative Escherichia coli and Klebsiella pneumoniae that were isolated from the corneal ulcer. This study provides a potential therapeutic option for multiple drug-resistant corneal pathogens that cause vision impairment.

Multi-functional xylanase from Aspergillus sydowii: biosynthesis of nanoconjugates, optimization by Taguchi approach and biodeinking potential

The search for effective production of xylanase which is an important industrial enzyme led to the present study that explored xylanase production by Aspergillus sydowii SF through Taguchi optimization that incorporated nanoconjugates in submerged fermentation. Calcium and zinc oxide nanoconjugates biosynthesized by xylanase were characterized via UV-Vis spectroscopy, Fourier transform infrared spectroscopy, and Transmission electron microscopy (TEM). The xylanase-mediated calcium oxide and zinc oxide nanoconjugates with λmax of 374 and 316 nm, respectively, and were 5.32-17.69 nm in size. Xylanase production was improved by 2.90-10.58 folds (64.24-234.15 U/mL) through Taguchi optimization cum nanoconjugates, and ANOVA showed that nanoconjugates contributed 13.62-65.97% to improved production. The xylanase had up to 88.38% deinking activity, with 49.60-84.64% removal of blue color. The remarkable xylanase production, its use to biosynthesize nanoconjugates and biodeinking potentials contribute to the development of versatile biocatalysts with applications in biotechnology, nanotechnology, and sustainable paper production. To the best of our knowledge, this represents the first report of xylanase for biosynthesis of calcium oxide and zinc oxide nanoparticles, as well as nanosupplementation to induce xylanase production, which can open new vista in bioprocess optimization.

Investigating the effect of acidic and basic precipitation on the antibacterial activity of ZnO nanoparticles against Gram-negative and Gram-positive bacteria

In the present work, acidic (direct) and basic precipitation (indirect) methods were used to demonstrate the influence of the mode of precipitation on the structural properties of ZnO nanoparticles (NPs). Four samples of ZnO nanoparticles were prepared, two samples via each mode of precipitation. DZOa and IZOa were the aged samples prepared via acidic and basic precipitation methods, and DZOwa and IZOwa were processed without aging. Both precipitation processes were carried out without using any surfactant reagents. Zinc hydroxide precipitate, which was formed during the basic precipitation method, could be critical in deciding the properties of ZnO NPs, unlike zinc hydroxide formed during acidic precipitation. Aging of zinc hydroxide, synthesised by basic precipitation method for 48 hours was found to be an added advantage in controlling the properties of ZnO NPs. The influence of the mode of precipitation on the structural properties and antibacterial activity of ZnO NPs against Gram-positive and Gram-negative bacterial strains was tested. The antibacterial activity of all four ZnO NPs was analysed via zone of inhibition measurements at a concentration dose of 200 μg ml-1. IZOa nanoparticles prepared using the basic precipitation method showed a higher antibacterial activity against three Gram-negative and one Gram-positive strains, namely, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. DZOa nanoparticles synthesized through acidic precipitation showed relatively high antibacterial activity against Salmonella typhimurium, a Gram-negative strain. ZnO NPs prepared without aging, IZOwa and DZOwa, showed a higher antibacterial activity against E. coli and Bacillus sp. strains, respectively. All ZnO NPs were characterized via UV-visible, FTIR, XRD, and HRSEM techniques.

Biosurfactant-capped CuO nanoparticles coated cotton/polypropylene fabrics toward antimicrobial textile applications

The global COVID-19 pandemic has led to an increase in the importance of implementing effective measures to prevent the spread of microorganisms. Consequently, there is a growing demand for antimicrobial materials, specifically antimicrobial textiles and face masks, because of the surge in diseases caused by bacteria and viruses like SARS-CoV-2. Face masks that possess built-in antibacterial properties can rapidly deactivate microorganisms, enabling reuse and reducing the incidence of illnesses. Among the numerous types of inorganic nanomaterials, copper oxide nanoparticles (CuO NPs) have been identified as cost-effective and highly efficient antimicrobial agents for inactivating microbes. Furthermore, biosurfactants have recently been recognized for their potential antimicrobial effects, in addition to inorganic nanoparticles. Therefore, this research's primary focus is synthesizing biosurfactant-mediated CuO NPs, integrating them into natural and synthetic fabrics such as cotton and polypropylene and evaluating the resulting fabrics' antimicrobial activity. Using rhamnolipid (RL) as a biosurfactant and employing a hydrothermal method with a pH range of 9-11, RL-capped CuO NPs are synthesized (RL-CuO NPs). To assess their effectiveness against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) microorganisms, the RL-CuO NPs are subjected to antibacterial testing. The RL-capped CuO NPs exhibited antimicrobial activity at much lower concentrations than the individual RL, CuO. RL-CuO NPs have shown a minimum inhibitory concentration (MIC) of 1.2 mg ml-1and minimum bactericidal concentration (MBC) of 1.6 mg ml-1forE. coliand a MIC of 0.8 mg ml-1and a MBC of 1.2 mg ml-1forS. aureus, respectively. Furthermore, the developed RL-CuO NPs are incorporated into cotton and polypropylene fabrics using a screen-printing technique. Subsequently, the antimicrobial activity of the coated fabrics is evaluated, revealing that RL-CuO NPs coated fabrics exhibited remarkable antibacterial properties against both gram-positive and gram-negative bacteria.

Fabrication of chitosan nanocomposites loaded with biosynthetic metallic nanoparticles and their therapeutic investigation

The present research demonstrates the formation of zinc oxide nanoparticles facilitated by Cissus quadrangularis (CQ-ZnONPs) and subsequent synthesis of chitosan-conjugated nanocomposites (CQ-CS/ZnONCs) along with their biological assessment. The biosynthesized nanoparticles and nanocomposites were physicochemically characterized and therapeutically assessed for their antioxidant, antibacterial, and antidiabetic potential. The formation of CQ-ZnONPs and CQ-CS/ZnONCs was preliminarily validated by the change in color and subsequently by UV-visible spectroscopic analysis. The crystalline peaks associated with the CQ-ZnONPs in CQ-CS/ZnONCs were established by XRD analysis. Morphological evaluation of CQ-ZnONPs and CQ-CS/ZnONCs was carried out through FE-SEM and HRTEM studies. The particle size of the CQ-ZnONPs and CQ-CS/ZnONCs was 243.3 nm and 176.6 nm, with a PDI of 0.188 and 0.199, respectively. Nanoparticles and nanocomposites expressed Zeta potential of -15.7 mV and -16.2 mV, respectively. The CQ-ZnONPs and CQ-CS/ZnONCs showed good radical effectiveness with various in-vitro assays. The formulated nanoparticles and nanocomposites displayed significant antibacterial activity against the selected bacterial pathogens. CQ-CS/ZnONCs presented noteworthy α-amylase and α-glucosidase inhibitory effects compared to CQ-ZnONPs with IC50 of 73.66 ± 1.21 μg/mL and 87.59 ± 1.29 μg/mL, respectively. Moreover, the synthesized CQ-CS/ZnONCs demonstrated 98.92 ± 0.39% and 99.58 ± 0.16% wound contraction (at 7 and 14 mg, respectively), significantly (p < 0.05) higher than the standard and CQ-ZnONPs. Thus, the CQ-ZnONPs and CQ-CS/ZnONCs could effectively develop promising drug delivery systems to inhibit pathogens and chronic tissue repair.

Biosynthesis and Characterization of Calcium Oxide Nanoparticles from Citrullus colocynthis Fruit Extracts; Their Biocompatibility and Bioactivities

Modern nanotechnology encompasses every field of life. Nowadays, phytochemically fabricated nanoparticles are being widely studied for their bioactivities and biosafety. The present research studied the synthesis, characterization, stability, biocompatibility, and in vitro bioactivities of calcium oxide nanoparticles (CaONPs). The CaONPs were synthesized using Citrullus colocynthis ethanolic fruit extracts. Greenly synthesized nanoparticles had an average size of 35.93 ± 2.54 nm and showed an absorbance peak at 325 nm. An absorbance peak in this range depicts the coating of phenolic acids, flavones, flavonols, and flavonoids on the surface of CaONPs. The XRD pattern showed sharp peaks that illustrated the preferred cubic crystalline nature of triturate. A great hindrance to the use of nanoparticles in the field of medicine is their extremely reactive nature. The FTIR analysis of the CaONPs showed a coating of phytochemicals on their surface, due to which they showed great stability. The vibrations present at 3639 cm^-1 for alcohols or phenols, 2860 cm^-1 for alkanes, 2487 cm^-1 for alkynes, 1625 cm^-1 for amines, and 1434 cm^-1 for carboxylic acids and aldehydes show adsorption of phytochemicals on the surface of CaONPs. The CaONPs were highly stable over time; however, their stability was slightly disturbed by varying salinity and pH. The dialysis membrane in vitro release analysis revealed consistent nanoparticle release over a 10-h period. The bioactivities of CaONPs, C. colocynthis fruit extracts, and their synergistic solution were assessed. Synergistic solutions of both CaONPs and C. colocynthis fruit extracts showed great bioactivity and biosafety. The synergistic solution reduced cell viability by only 14.68% and caused only 16% hemolysis. The synergistic solution inhibited Micrococcus luteus slightly more effectively than streptomycin, with an activity index of 1.02. It also caused an 83.87% reduction in free radicals.

New frontiers of invasive plants for biosynthesis of nanoparticles towards biomedical applications: A review

Above 1000 invasive species have been growing and developing ubiquitously on Earth. With extremely vigorous adaptability, strong reproduction, and spreading powers, invasive species have posed an alarming threat to indigenous plants, water quality, soil, as well as biodiversity. It was estimated that an economic loss of billions of dollars or equivalent to 1 % of gross domestic product as a consequence of lost crops, control efforts, and damage costs caused by invasive plants in the United States. While eradicating invasive plants from the ecosystems is practically infeasible, taking advantage of invasive plants as a sustainable, locally available, and zero-cost source to provide valuable phytochemicals for bionanoparticles fabrication is worth considering. Here, we review the harms, benefits, and role of invasive species as important botanical sources to extract natural compounds such as piceatannol, resveratrol, and quadrangularin-A, flavonoids, and triterpenoids, which are linked tightly to the formation and application of bionanoparticles. As expected, the invasive plant-mediated bionanoparticles have exhibited outstanding antibacterial, antifungal, anticancer, and antioxidant activities. The mechanism of biomedical activities of the invasive plant-mediated bionanoparticles was insightfully addressed and discussed. We also expect that this review not only contributes to efforts to combat invasive plant species but also opens new frontiers of bionanoparticles in the biomedical applications, therapeutic treatment, and smart agriculture.

Biocatalysis as a Green Approach for Synthesis of Iron Nanoparticles—Batch and Microflow Process Comparison

There is a growing need for production of iron particles due to their possible use in numerous systems (e.g., electrical, magnetic, catalytic, biological and others). Although severe reaction conditions and heavy solvents are frequently used in production of nanoparticles, green synthesis has arisen as an eco-friendly method that uses biological catalysts. Various precursors are combined with biological material (such as enzymes, herbal extracts, biomass, bacteria or yeasts) that contain chemicals from the main or secondary metabolism that can function as catalysts for production of nanoparticles. In this work, batch (“one-pot”) biosynthesis of iron nanoparticles is reviewed, as well as the possibilities of using microfluidic systems for continuous biosynthesis of iron nanoparticles, which could overcome the limitations of batch synthesis.

Anticancer cytotoxicity and antifungal abilities of green-synthesized cobalt hydroxide (Co(OH)2) nanoparticles using Lantana camara L

Background

Green synthesis of metal nanoparticles with pharmaceutical applications is the current focus in the field of nanomedicine. This study aims at use of Lantanacamara L as a source of green reducing agent toward synthesis of cobalt nanoparticles.

Results

Fe3+-reducing assay demonstrated that Lantana camara methanol extract (LCM) has significant electron transfer potential. Gas chromatography mass spectroscopy (GC–MS) analysis of the crude extracts revealed the presence of 7 known and 17 unknown phytochemicals in LCM. Synthesis of cobalt nanoparticles was confirmed based on color change of reaction mixture from light brown to dark brown. UV–visible spectrometry analysis showed that the synthesized particles had a λmax at 267.5 nm. Based on the two theta (2θ) and Miller indices (hkl) values obtained in XRD analysis, the particles were confirmed to be cobalt hydroxide (Co(OH)2) nanoparticles. Further dynamic light scattering (DLS) analysis showed that the average size of the Co(OH)2 nanoparticles is 180 nm. SEM image analysis of the particles revealed that they are spherical mass of feather-like structure, contributing toward increased surface area of the particles. Further, the pharmaceutical potential of the Co(OH)2 nanoparticles was evaluated against eukaryotic cancer and fungal cells. MTT cytotoxicity analysis showed that Co(OH)2 nanoparticles have selective toxicity toward HCT-116 cancer cells with an IC50 value of 25 µg/ml and reduced cytotoxicity to non-cancerous VERO cells with an IC50 value of 200 µg/ml suggesting that the particles possess selective anti-cancerous cytotoxicity. Additionally, the particles demonstrated significant antifungal activity against 5 human fungal pathogens.

Conclusions

Results of this study conclude that green-synthesized Co(OH)2 nanoparticles using Lantanacamara L possess excellent eukaryotic cytotoxicity against cancer cells and fungal pathogens.

The emergence of metal oxide nanoparticles (NPs) as a phytomedicine: A two-facet role in plant growth, nano-toxicity and anti-phyto-microbial activity

Anti-microbial resistance (AMR) has recently emerged as an area of high interest owing to the rapid surge of AMR phenotypes. Metal oxide NPs (MeONPs) have been identified as novel phytomedicine and have recently peaked a lot of interest due to their potential applications in combating phytopathogens, besides enhancing plant growth and yields. Numerous MeONPs (Ti₂O, MgO, CuO, Ag₂O, SiO₂, ZnO, and CaO) have been synthesized and tested to validate their antimicrobial roles without causing toxicity to the cells. This review discusses the application of the MeONPs with special emphasis on anti-microbial activities in agriculture and enlists how cellular toxicity caused through reactive oxygen species (ROS) production affects plant growth, morphology, and viability. This review further highlights the two-facet role of silver and copper oxide NPs including their anti-microbial applications and toxicities. Furthermore, the factor modulating nanotoxicity and immunomodulation for cytokine production has also been discussed. Thus, this article will not only provide the researchers with the potential bottlenecks but also emphasizes a comprehensive outline of breakthroughs in the applicability of MeONPs in agriculture.

Combination Strategies of Different Antimicrobials: An Efficient and Alternative Tool for Pathogen Inactivation

Despite the discovery and development of an array of antimicrobial agents, multidrug resistance poses a major threat to public health and progressively increases mortality. Recently, several studies have focused on developing promising solutions to overcome these problems. This has led to the development of effective alternative methods of controlling antibiotic-resistant pathogens. The use of antimicrobial agents in combination can produce synergistic effects if each drug invades a different target or signaling pathway with a different mechanism of action. Therefore, drug combinations can achieve a higher probability and selectivity of therapeutic responses than single drugs. In this systematic review, we discuss the combined effects of different antimicrobial agents, such as plant extracts, essential oils, and nanomaterials. Furthermore, we review their synergistic interactions and antimicrobial activities with the mechanism of action, toxicity, and future directions of different antimicrobial agents in combination. Upon combination at an optimum synergistic ratio, two or more drugs can have a significantly enhanced therapeutic effect at lower concentrations. Hence, using drug combinations could be a new, simple, and effective alternative to solve the problem of antibiotic resistance and reduce susceptibility.

Nanohybrids of oxides nanoparticles-chitosan and their antimicrobial properties

Growing international problem with pathogens acquiring resistance to antibiotics is the reason for the search for bactericidal substances against which microorganisms cannot become resistant. The aim of this study was to synthesize inorganic-organic nanohybrids and obtain materials with antimicrobial effects. Chitosan (CS) was deposited on nanocomposite carriers such as calcium oxide with titanium dioxide (CaO-TiO₂), magnesium oxide with titanium dioxide (MgO-TiO₂) and copper(II) oxide with titanium dioxide (CuO-TiO₂). The efficiency of the process was examined at varying concentrations of chitosan and temperature. The parameters for nanohybrids synthesis were selected based on the highest amount of nano-chitosan deposited on the nanohybrids-for each carrier, the process conditions were as follows: chitosan solution at 5 g l^-1and 20 °C. The materials were obtained using these parameters and were used for microbiological tests againstE. coliATCC 25922,S. aureusATCC 25923 andC. albicansATCC 10231. The growth inhibitory activity of the obtained materials was qualitatively defined. These results suggest that the synthesized nanohybrids and nanocomposites exhibit biostatic action. The material with the broadest effect was the CuO-TiO₂-CS hybrid, which had biostatic properties against all tested strains at a minimal concentration of 1250μg ml^-1. Further research is required to find eco-friendly, non-toxic, and more effective antimicrobials with a broad action to prevent the acquisition of resistance.

Microwave assisted biodiesel production from chicken feather meal oil using Bio-Nano Calcium oxide derived from chicken egg shell

Environmental concerns have initiated the search for greener measures to mitigate pollution issues. Bio Nano CaO was synthesized by reducing CaO extracted from chicken egg shell using tea decoction. The synthesized material was characterized by physico-chemical techniques such as XRD, TGA, BET surface area analyser, TGA and SEM techniques. XRD studied confirmed the crystalline nature of material. The prepared material was found to be stable till 450 ^οC from TGA study. The SEM pictures displayed uniform and discrete particles which portrays the high probable sites that maximises the catalytic activity. The optimization of microwave assisted Biodiesel synthesis from chicken feather oil through Transesterification process using the bio-synthesized catalytic material was the main aim of the study. A 500 W microwave irradiation of Chicken feather meal oil using 8:1 Methanol:Oil input, 1% Bio Nano CaO concentration, 5 min of reaction time resulted in 95% conversion of chicken feather meal oil into chicken feather meal methyl esters. The Biodiesel was showed low viscosity (4.15 mm²/s), high heating value (50 MJ/kg), high flash point (153^οC), reasonable pour point (12 ^οC) and good cetane number (50 min). The future works will be concentrated on the engine studies related to Torque, fuel consumption, emission data by using the synthesized Biodiesel.

Green approaches for the synthesis of metal and metal oxide nanoparticles using microbial and plant extracts

Green synthesis approaches are gaining significance as promising routes for the sustainable preparation of nanoparticles, offering reduced toxicity towards living organisms and the environment. Nanomaterials produced by green synthesis approaches can offer additional benefits, including reduced energy inputs and lower production costs than traditional synthesis, which bodes well for commercial-scale production. The biomolecules and phytochemicals extracted from microbes and plants, respectively, are active compounds that function as reducing and stabilizing agents for the green synthesis of nanoparticles. Microorganisms, such as bacteria, yeasts, fungi, and algae, have been used in nanomaterials' biological synthesis for some time. Furthermore, the use of plants or plant extracts for metal and metal-based hybrid nanoparticle synthesis represents a novel green synthesis approach that has attracted significant research interest. This review discusses various biosynthesis approaches via microbes and plants for the green preparation of metal and metal oxide nanoparticles and provides insights into the molecular aspects of the synthesis mechanisms and biomedical applications. The use of agriculture waste as a potential bioresource for nanoparticle synthesis and biomedical applications of biosynthesized nanoparticles is also discussed.

Green approaches for the synthesis of metal and metal oxide nanoparticles using microbial and plant extracts

Green synthesis approaches are gaining significance as promising routes for the sustainable preparation of nanoparticles, offering reduced toxicity towards living organisms and the environment.

Multimetallic Nanoparticles as Alternative Antimicrobial Agents: Challenges and Perspectives

Recently, infectious diseases caused by bacterial pathogens have become a major cause of morbidity and mortality globally due to their resistance to multiple antibiotics. This has triggered initiatives to develop novel, alternative antimicrobial materials, which solve the issue of infection with multidrug-resistant bacteria. Nanotechnology using nanoscale materials, especially multimetallic nanoparticles (NPs), has attracted interest because of the favorable physicochemical properties of these materials, including antibacterial properties and excellent biocompatibility. Multimetallic NPs, particularly those formed by more than two metals, exhibit rich electronic, optical, and magnetic properties. Multimetallic NP properties, including size and shape, zeta potential, and large surface area, facilitate their efficient interaction with bacterial cell membranes, thereby inducing disruption, reactive oxygen species production, protein dysfunction, DNA damage, and killing potentiated by the host's immune system. In this review, we summarize research progress on the synergistic effect of multimetallic NPs as alternative antimicrobial agents for treating severe bacterial infections. We highlight recent promising innovations of multimetallic NPs that help overcome antimicrobial resistance. These include insights into their properties, mode of action, the development of synthetic methods, and combinatorial therapies using bi- and trimetallic NPs with other existing antimicrobial agents.

Green Synthesis of Metallic Nanoparticles and Their Prospective Biotechnological Applications: an Overview

The green synthesis of nanoparticles (NPs) using living cells is a promising and novelty tool in bionanotechnology. Chemical and physical methods are used to synthesize NPs; however, biological methods are preferred due to its eco-friendly, clean, safe, cost-effective, easy, and effective sources for high productivity and purity. High pressure or temperature is not required for the green synthesis of NPs, and the use of toxic and hazardous substances and the addition of external reducing, stabilizing, or capping agents are avoided. Intra- or extracellular biosynthesis of NPs can be achieved by numerous biological entities including bacteria, fungi, yeast, algae, actinomycetes, and plant extracts. Recently, numerous methods are used to increase the productivity of nanoparticles with variable size, shape, and stability. The different mechanical, optical, magnetic, and chemical properties of NPs have been related to their shape, size, surface charge, and surface area. Detection and characterization of biosynthesized NPs are conducted using different techniques such as UV-vis spectroscopy, FT-IR, TEM, SEM, AFM, DLS, XRD, zeta potential analyses, etc. NPs synthesized by the green approach can be incorporated into different biotechnological fields as antimicrobial, antitumor, and antioxidant agents; as a control for phytopathogens; and as bioremediative factors, and they are also used in the food and textile industries, in smart agriculture, and in wastewater treatment. This review will address biological entities that can be used for the green synthesis of NPs and their prospects for biotechnological applications.

Aqueous extract of broccoli mediated synthesis of CaO nanoparticles and its application in the photocatalytic degradation of bromocrescol green

CaO nanoparticles have been prepared using CaCl₂ and aqueous extract of broccoli as a precursor and reducing agent, respectively. Different volumes of the aqueous broccoli extract were utilised to obtain Ca(OH)₂ and subsequent calcination gave CaO nanoparticles. The synthesised CaO was confirmed by powder X-ray diffraction (XRD). The morphology was studied using transmittance electron microscopy (TEM), and the surface composition of Ca(OH)₂ was explored using Fourier transform infrared spectroscopy. The major functional groups present in the capping material responsible for the reduction of the metal salt and the surface passivation of Ca(OH)₂ were identified. The XRD pattern revealed cubic phase for all the CaO nanoparticles, and the crystallite size was estimated using Scherrer's equation showed a variation which is dependent on the volume of the extract used. TEM analysis showed different shapes, while the selected area electron diffraction (SAED) results confirmed the crystallinity of the nanoparticles. Thermogravimetric analysis of Ca(OH)₂ showed the decomposition product to be CaO. Sample C3, which has the smallest particle size, was used as a catalyst for the degradation of bromocresol green via photo irradiation with ultraviolet light and the result revealed a degradation efficiency of 60.1%.

Biosynthesis of Ultrasonically Modified Ag-MgO Nanocomposite and Its Potential for Antimicrobial Activity

This study reports a green synthesis route for a bilayered Ag-MgO nanocomposite using aqueous peel extract of Citrus paradisi (grapefruit red) under an accelerated uniform heating technique and its antibacterial potency against Escherichia coli. Surface modifications and composition of the nanocomposite were examined using a UV-visible spectrophotometer, transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) equipped with an energy dispersive X-ray (EDX) analyzer. The efficiencies of the as-synthesized Ag-MgO nanocomposite against Escherichia coli were examined. The synthesized Ag-MgO nanocomposite showed characteristic synergetic bands at 290 nm for MgO nanoparticle and at around 440 nm for Ag nanoparticle which blue-shifted to 380 nm in the composite. A spherically dispersed nanocomposite with cubical crystal lattice network with a diameter of about 20–100 nm comprising Ag nanoparticle embedded within MgO nanoparticles was obtained. The nanocomposite produced stronger antibacterial activity against Escherichia coli as compared to MgO nanoparticle, indicating a higher interaction between Ag and MgO ions. The nanocomposite was successfully synthesized via an efficient modified method by bioreductive agents with an improved synergistic antibacterial property towards water purification.