Inhibition of growth and biofilm formation of clinical bacterial isolates by NiO nanoparticles synthesized from Eucalyptus globulus plants

Microbial Population Dynamics in Model Sewage Treatment Plants and the Fate and Effect of Gold Nanoparticles

Adequate functioning of a sewage treatment plant (STP) is essential to protect the downstream aquatic environment (ECHA 2017), and information on the degradability of chemicals and their toxicity to activated sludge microorganisms is required. An environmental realistic higher tier test is a STP simulation test as described in OECD 303A (2001) which for nanoparticles can also be used to study their sorption behavior to activated sludge. However, information is limited on the influence of synthetic sewage on the microbial community of the activated sludge. A modified community can result in modifications of the sludge floccules affecting the sorption behavior. The main objective of our study was to show whether a representative microbial diversity remains under standardized test conditions as described in OECD 303A (2001) using synthetic sewage as influent. Furthermore, we investigated whether just considering the functional properties of a STP (elimination of dissolved organic carbon; nitrification), is sufficient for an assessment of gold nanoparticles (AuNPs) or whether the influence on microbial diversity also needs to be considered. AuNPs were used as a case study due to their rising medical applications and therefore increasing probability to reach the sewer and STP. The results can provide significant input for the interpretation of results from the regulatory point of view. To deliver these objectives, the general changes of the microbial population in activated sludge and its influence on the degradation activity (dissolved organic carbon (DOC) and inorganic nitrogen) using freshly collected sludge from the municipal STP in an artificial test system as a model STP in accordance with OECD 303A (2001) were assessed. Additionally, we evaluated the potential impact of AuNPs and its dispersant on the microbial composition and the overall impact on the function of the STP in terms of DOC degradation and nitrogen removal to observe if an assessment based on functional properties is sufficient. The bacteria composition in our study, evaluated at a class level, revealed commonly described environmental bacteria. Proteobacteria (β, α, δ) accounted for more than 50% but also nitrifying bacteria as Nitrospira were present. Our results show that mainly within the first 7 days of an acclimatization phase by addition of synthetic sewage, the bacterial community changed. Even though AuNPs can have antibacterial properties, no adverse effects on the function and structure of the microorganisms in the STP could be detected at concentrations of increased modeled PEC values by a factor of about 10,000. Complementary to other metallic nanomaterials, gold nanomaterials also sorb to a large extent to the activated sludge. If activated sludge is used as fertilizer on agricultural land, gold nanoparticles can be introduced into soils. In this case, the effect on soil (micro)organisms must be investigated more closely, also taking into account the structural diversity.

Padina boryana mediated green synthesis of crystalline palladium nanoparticles as potential nanodrug against multidrug resistant bacteria and cancer cells

Green synthesized nanoparticles (NPs) have emerged as a new and promising alternative to overcome the drug resistance problem. Peculiar nano-specific features of palladium NPs (Pd-NPs) offer invaluable possibilities for clinical treatment. Due to the development of multi-drug resistance (MDR) in pathogenic bacteria and the prevalence of cancers, use of algae-mediated Pd-NPs could be a prospective substitute. Therefore, Pd-NPs were synthesized by a one-step, cost-effective, and environmentally friendly green method using the extract from a brown alga, Padina boryana (PB-extract), and evaluated for their antibacterial, antibiofilm, and anticancer activities. Pd-NPs were physicochemically characterized for size, shape, morphology, surface area, charge, atomic composition, crystal structure, and capping of Pd-NPs by PB-extract biomolecules by various techniques. The data revealed crystalline Pd-NPs with an average diameter of 8.7 nm, crystal size/structure of 11.16 nm/face-centered cubic, lattice d-spacing of 0.226 nm, 28.31% as atomic percentage, surface area of 16.1 m2/g, hydrodynamic size of 48 nm, and zeta-potential of - 28.7 ± 1.6 mV. Fourier-transform infrared spectroscopy (FT-IR) analysis revealed the role of PB-extract in capping of Pd-NPs by various functional groups such as -OH, C=C, C-O, and C-N from phenols, aliphatic hydrocarbons, aromatic rings, and aliphatic amine. Out of 31, 23 compounds were found involved in biosynthesis by Gas chromatography-mass spectrometry (GC-MS) analysis. Isolated strains were identified as MDR Staphylococcus aureus, Escherichia fergusonii, Acinetobacter pittii, Pseudomonas aeruginosa, Aeromonas enteropelogenes, and Proteus mirabilis and Pd-NPs exhibited strong antibacterial/antibiofilm activities against them with minimum inhibitory concentration (MIC) in the range of 62.5-125 μg/mL. Moreover, cell viability assays showed concentration-dependent anti-proliferation of breast cancer MCF-7 cells. Pd-NPs also enhanced mRNA expression of apoptotic marker genes in the order: p53 (5.5-folds) > bax (3.5-folds) > caspase-3 (3-folds) > caspase-9 (2-folds) at 125 μg/mL. This study suggested the possible role of PB-extract capped Pd-NPs for successful clinical management of MDR pathogens and breast cancer cells.

Synthesis of gallotannin capped iron oxide nanoparticles and their broad spectrum biological applications

Green synthesized nanoparticles (NPs) have attracted enormous attention for their clinical and non-clinical applications. A natural polyphenol, gallo-tannin (GT) was used to reduce and cap the Fe2O3-NPs. GT-Fe2O3-NPs were synthesized following co-precipitation of FeCl3 and FeSO4·7H2O with GT. Fe2O3-NPs absorbed light at 380 nm. Physicochemically, Fe2O3-NPs were spherical with slight aggregation and average diameter of 12.85 nm. X-ray diffraction confirmed crystallinity and EDX revealed the elemental percentage of iron and oxygen as 21.7% and 42.11%, respectively. FT-IR data confirmed the adsorption of gallo-tannin functional groups. Multiple drug-resistant (MDR) Escherichia coli (ESβL), Pseudomonas aeruginosa (ESβL), and Staphylococcus aureus were found susceptible to 500-1000 μg GT-Fe2O3-NPs per ml. In synergy, Fe2O3-NPs enhanced the efficiency of some antibiotics. GT-Fe2O3 NPs showed significant (P ≤ 0.05) inhibition of growth and biofilm against MDR E. coli, P. aeruginosa, and S. aureus causing morphological and biofilm destruction. Violacein production (quorum sensing mediated) by C. violaceum was inhibited by GT-Fe2O3-NPs in a concentration-dependent manner with a maximum decrease of 3.1-fold. A decrease of 11-fold and 2.32-fold in fungal mycelial growth and human breast cancer (MCF-7) cell viability, respectively was evident. This study suggests a plausible role of gallo-tannin capped Fe2O3-NPs as an alternative antibacterial, antiquorum sensing, antibiofilm, antifungal, and anti-proliferative agent.

Structural, Optical and Antibacterial Efficacy of Pure and Zinc-Doped Copper Oxide against Pathogenic Bacteria

Copper oxide and Zinc (Zn)-doped Copper oxide nanostructures (CuO-NSs) are successfully synthesized by using a hydrothermal technique. The as-obtained pure and Zn-doped CuO-NSs were tested to study the effect of doping in CuO on structural, optical, and antibacterial properties. The band gap of the nanostructures is calculated by using the Tauc plot. Our results have shown that the band gap of CuO reduces with the addition of Zinc. Optimization of processing conditions and concentration of precursors leads to the formation of pine needles and sea urchin-like nanostructures. The antibacterial properties of obtained Zn-doped CuO-NSs are observed against Gram-negative (Pseudomonas aeruginosa, Klebsiella pneumonia, Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria via the agar well diffusion method. Zn doped s are found to have more effective bacterial resistance than pure CuO. The improved antibacterial activity is attributed to the reactive oxygen species (ROS) generation.

Impact of metal-oxide nanoparticles on growth, physiology and yield of tomato (Solanum lycopersicum L.) modulated by Azotobacter salinestris strain ASM

The current study for the first time demonstrates the interference of a free-living, N₂-fixing, and nanoparticle (NP) tolerant Azotobacter salinestris strain ASM recovered from metal-polluted soil with tomato plant-metal oxide NPs (ZnO, CuO, Al₂O_3, and TiO₂) interactions in a sandy clay loam soil system with bulk materials as control. Tomato plants were grown till full maturity in soils amended with 20-2000 mg kg^-1 of each metal-oxide NP with and without seed biopriming and root-inoculation of A. salinestris. A. salinestris was found metabolically active, producing considerably high amounts of bioactive indole-3-acetic-acid, morphologically unaffected, and with low alteration of cell membrane permeability under 125-1500 μgml^-1 of NPs. However, ZnO-NPs slightly alter bacterial membrane permeability. Besides, A. salinestris secreted significantly higher amounts of extracellular polymeric substance (EPS) even under NP exposure, which could entrap the NPs and form metal-EPS complex as revealed and quantified by SEM-EDX. NPs were also found adsorbed on bacterial biomass. EPS stabilized the NPs and provided negative zeta potential to NPs. Following soil application, A. salinestris improved the plant performance and augmented the yield of tomato fruits and lycopene content even in NPs stressed soils. Interestingly, A. salinestris inoculation enhanced photosynthetic pigment formation, flower attributes, plant and fruit biomass, and reduced proline level. Bacterial inoculation also reduced the NP's uptake and accumulation significantly in vegetative organs and fruits. The organ wise order of NP's internalization was roots > shoots > fruits. Conclusively, A. salinestris inoculation could be an alternative to increase the production of tomato in metal-oxide NPs contaminated soils.

Metal Oxide Nanoparticles Against Bacterial Biofilms: Perspectives and Limitations

At present, there is an urgent need in medicine and industry to develop new approaches to eliminate bacterial biofilms. Considering the low efficiency of classical approaches to biofilm eradication and the growing problem of antibiotic resistance, the introduction of nanomaterials may be a promising solution. Outstanding antimicrobial properties have been demonstrated by nanoparticles (NPs) of metal oxides and their nanocomposites. The review presents a comparative analysis of antibiofilm properties of various metal oxide NPs (primarily, CuO, Fe3O4, TiO2, ZnO, MgO, and Al2O3 NPs) and nanocomposites, as well as mechanisms of their effect on plankton bacteria cells and biofilms. The potential mutagenicity of metal oxide NPs and safety problems of their wide application are also discussed.

Antimicrobial metal-based nanoparticles: a review on their synthesis, types and antimicrobial action

The investigation of novel nanoparticles with antimicrobial activity has grown in recent years due to the increased incidence of nosocomial infections occurring during hospitalization and food poisoning derived from foodborne pathogens. Antimicrobial agents are necessary in various fields in which biological contamination occurs. For example, in food packaging they are used to control food contamination by microbes, in the medical field the microbial agents are important for reducing the risk of contamination in invasive and routine interventions, and in the textile industry, they can limit the growth of microorganisms due to sweat. The combination of nanotechnology with materials that have an intrinsic antimicrobial activity can result in the development of novel antimicrobial substances. Specifically, metal-based nanoparticles have attracted much interest due to their broad effectiveness against pathogenic microorganisms due to their high surface area and high reactivity. The aim of this review was to explore the state-of-the-art in metal-based nanoparticles, focusing on their synthesis methods, types, and their antimicrobial action. Different techniques used to synthesize metal-based nanoparticles were discussed, including chemical and physical methods and "green synthesis" methods that are free of chemical agents. Although the most studied nanoparticles with antimicrobial properties are metallic or metal-oxide nanoparticles, other types of nanoparticles, such as superparamagnetic iron-oxide nanoparticles and silica-releasing systems also exhibit antimicrobial properties. Finally, since the quantification and understanding of the antimicrobial action of metal-based nanoparticles are key topics, several methods for evaluating in vitro antimicrobial activity and the most common antimicrobial mechanisms (e.g., cell damage and changes in the expression of metabolic genes) were discussed in this review.

Secondary metabolites and anti-microbial/anti-oxidant profiles in Ocimum spp.: Role of soil physico-chemical characteristics as eliciting factors

Ocimum has long been used as a medicinal plant, although little information is available about its bioactive ingredients, and the influence of soil properties on modulation of secondary metabolites in Ocimum has yet to be ascertained. In this study, we present a thorough survey of all potential metabolic compounds in O. sanctum and O. basilicum. In both species, certain compounds (e.g., quercetin, kaempferol, catechin, and S-adenosyl homocysteine) were detected coincidently. In the case of O. basilicum, other vital phenolic acids (e.g., ursolic, vanilic, coumaric, and syringic acids) were identified. The aqueous extracts (AEs) of Ocimum recorded decrease of 6-94% in the proliferation of pathogenic bacteria (e.g., Listeria monocytogenes, Staphylococcus sp., Salmonella sp., and Bacillus sp.). The AEs also showed effective antioxidant activity by reducing free radicals by a factor of 1.04-1.13. Root-zone soil samples of both Ocimum spp. were collected from strategic locations with varying levels of key soil attributes (e.g., soil organic carbon (SOC), microbial biomass carbon (MBC), urease, and phosphatase). At high levels of SOC, MBC, and soil enzymes, the bioactivity of Ocimum spp. was observed to be promoted, especially with respect to secondary metabolite expression, anti-pathogenic activity, and anti-oxidant properties. As such, the findings of strong correlations between secondary metabolite concentrations and bioactivity attributes in Ocimum suggest the potent role of soil quality in eliciting the production of secondary metabolite in association with bioactivity in Ocimum spp.

Green Synthesized Phytochemically (Zingiber officinale and Allium sativum) Reduced Nickel Oxide Nanoparticles Confirmed Bactericidal and Catalytic Potential

Phyto-synthesized nanoparticles (NPs) having reduced chemical toxicity have been focused globally and become essential component of nanotechnology recently. We prepared green phytochemically (ginger and garlic) reduced NiO-NPs to replace synthetic bactericidal and catalytic agent in textile industry. NPs were characterized using ultra-violet visible spectroscopy (UV-Vis), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The synthesis of NPs was confirmed by XRD and UV-Vis having strong absorption at 350 nm with size ranged between 16-52 nm for ginger and 11-59 nm for garlic. Scanning and transmission electron microscopy confirmed pleomorphism with cubic- and more spherical-shaped NPs. Moreover, exact quantities of garlic and ginger extracts (1:3.6 ml) incorporated to synthesize NiO-NPs have been successfully confirmed by FTIR. Phytochemically reduced NPs by garlic presented enhanced bactericidal activity against multiple drug-resistant Staphylococcus aureus at increasing concentrations (0.5, 1.0 mg/50 μl) and also degraded methylene blue (MB) dye efficiently. Conclusively, green synthesized NiO-NPs are impending activists to resolve drug resistance as well as environment friendly catalytic agent that may be opted at industrial scale.

Responses of Eucalyptus globulus and Ficus nitida to different potential of heavy metal air pollution

The present study aimed to explore the tolerance potential of Cd, Pb and Cu and physiological alterations in two common tree species growing in Minia governorate (Egypt) namely: Eucalyptus globulus and Ficus nitida and to investigate the leaf features [leaf area (LA) and specific leaf area (SLA)] associated with the phytoremediation process. The findings may be useful for future surveillance as preliminary reference values for levels of heavy metals in urban and industrial settings. The levels of cadmium, lead and Cupper in plant leaf were determined. The results showed that heavy metals could inhibit the growth of plants including LA and SLA. The water content (WC) and photosynthetic pigments of Eucalyptus and Ficus decreased with the increased concentration of metals. Contrary to chlorophylls (a) and (b), carotenoids and chlorophyll ratio (a/b) showed a significant increase with increasing metals concentration especially that of Cd and Cu. Proline content was relatively increased and soluble carbohydrate content decreased in plants with high metal accumulation. Eucalyptus showed better tolerance capacity for Cd, Pb and Cu when compared to Ficus. The ability of Eucalyptus to accumulate and tolerate metal stress makes this species a good candidate to recuperate heavy metals-contaminated conditions.

An Overview of the Applications of Nanomaterials and Nanodevices in the Food Industry

The efficient progress in nanotechnology has transformed many aspects of food science and the food industry with enhanced investment and market share. Recent advances in nanomaterials and nanodevices such as nanosensors, nano-emulsions, nanopesticides or nanocapsules are intended to bring about innovative applications in the food industry. In this review, the current applications of nanotechnology for packaging, processing, and the enhancement of the nutritional value and shelf life of foods are targeted. In addition, the functionality and applicability of food-related nanotechnologies are also highlighted and critically discussed in order to provide an insight into the development and evaluation of the safety of nanotechnology in the food industry.

Phytogenic Generation of NiO Nanoparticles Using Stevia Leaf Extract and Evaluation of Their In-Vitro Antioxidant and Antimicrobial Properties

In the present study, economically viable NiO nanoparticles were produced by biogenic preparation using stevia leaf broth and their in-vitro antioxidant and antimicrobial activities were evaluated. The properties of the prepared NiO nanoparticles were confirmed by analytical techniques such as Ultraviolet-Visible (UV-Vis), X-ray diffraction (XRD), FE-SEM, and Fourier transform infrared spectroscopy (FTIR) analyses. Morphological studies using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the size of synthesized nanoparticles ranged from 20 to 50 nm, most of which were spherical and few of which were agglomerated. The role of the biological moieties, which reduce and cap the nanoparticles, was studied using FTIR analysis. The prepared nanoparticles strongly inhibited gram-negative bacteria, which is a camper with gram-positive bacteria and fungi. Furthermore, it performs an effective in-vitro activity through α,α-diphenyl-β-picrylhydrazyl (DPPH) reduction. Thus, it can be concluded that the effective and easy green synthesis process used for NiO nanoparticles provides potential antimicrobial agents against multidrug-resistant microbes.

Interaction of Copper-Based Nanoparticles to Soil, Terrestrial, and Aquatic Systems: Critical Review of the State of the Science and Future Perspectives

In the past two decades, increased production and usage of metallic nanoparticles (NPs) have inevitably increased their discharge into the different compartments of the environment, which ultimately paved the way for their uptake and accumulation in various trophic levels of the food chain. Due to these issues, several questions have been raised on the usage of NPs in everyday life and have become a matter of public health concern. Among the metallic NPs, Cu-based NPs have gained popularity due to their cost-effectiveness and multifarious promising uses. Several studies in the past represented the phytotoxicity of Cu-based NPs on plants. However, comprehensive knowledge is still lacking. Additionally, the impact of Cu-based NPs on soil organisms such as agriculturally important microbes, fungi, mycorrhiza, nematode, and earthworms is poorly studied. This review article critically analyses the literature data to achieve a more comprehensive knowledge on the toxicological profile of Cu-based NPs and increase our understanding of the effects of Cu-based NPs on aquatic and terrestrial plants as well as on soil microbial communities. The underlying mechanism of biotransformation of Cu-based NPs and the process of their penetration into plants have also been discussed herein. Overall, this review could provide valuable information to design rules and regulations for the safe disposal of Cu-based NPs into a sustainable environment.

Devising Carbon Nanotube, Green Tea, and Polyaniline Based Nanocomposite plus Investigating Its Rheological together with Bactericidal Efficacies

Subsequently, engines are designed to operate at low viscosity engine oils. Low viscosity oils take less power from engines, bring down the internal drag, cut the fuel consumption, and ultimately improve the engine's efficiency. Considering this focus, an approach has been made to formulate a multiwalled carbon nanotube based green tea and polyaniline nanocomposite, that is, GT/MWCNT/PANI, and incorporate it in engine oil (base fluid). The objective was to reduce the viscosity of engine oil by examining the effects of the constant shear rate and varying shear rates on the viscosity of Castrol class 15W-40 engine oil. The investigation was performed at a constant temperature of 25 °C for a fixed volume fraction of 0.1% GT/MWCNT/PANI in engine oil on the experimental setup rheometer from Anton Paar Series. Primordial findings revealed that, at a constant shear rate of 100 s-1, engine oil viscosity was lowered from 0.221000 to 0.001402 Pa·s, that is, 99% reduction in viscosity of the engine oil, after incorporating the GT/MWCNT/PANI nanocomposite. Furthermore, a new correlation has been proposed considering the experimental and theoretical models with an average percentage error of 0.040%. Also, at varying shear rates, up to 90 s-1, the shear viscosity of nanofluid decreases significantly, leading to shear-thinning behavior of the nanofluid, while at a shear rate of >90 s-1, it shows Newtonian behavior. Besides, the ternary nanocomposite with 0.2 wt % GT/MWCNT/PANI also showed significant bactericidal effects with the zones of inhibition of 19, 18, and 15 mm against Gram-negative (Pseudomonas aeruginosa, Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria, respectively, as measured using the well diffusion method.

Effective Inhibition of Phytopathogenic Microbes by Eco-Friendly Leaf Extract Mediated Silver Nanoparticles (AgNPs)

ABSTRACT

This study was aimed at producing the eco-friendly, safe, and inexpensive silver (Ag) nanoparticles (NPs) and assessing its antimicrobial activity. Fungal pathogens isolated from diseased leaves and fruits of brinjal and bacterial pathogen obtained from a culture collection were used in this study. Green synthesis of AgNPs was performed and optimized using Azadirachta indica leaf extract. The newly synthesized AgNPs (λmax = 437 nm) showed isotropism in size (crystal size/diameter: 21/29 ± 5 nm) and morphology under transmission and scanning electron microscopy and energy dispersive X-ray analysis. The fourier transform infrared spectroscopy data suggested the role of various aliphatic/aromatic moieties and proteins in AgNPs stabilization. The AgNPs reduced the growth of Penicillium sp. maximally by 92% after 6 days. The sensitivity of test fungi towards AgNPs followed the order: Penicillium sp. (92%) > Fusarium sp. (89%) > Aspergillus sp. (69%). Exposure of Ralstonia solanacearum to AgNPs (MIC/MBC 200/400 µg ml-1) displayed damaged cellular envelopes, bulging of cells, and pit formation. The nucleic acid discharge showed a progressive increase from 8 to 34% (r2 = 0.97). The cellular metabolic activity and surface adhering ability of R. solanacearum were completely lost at 400 µgAgNPs ml-1. Results suggested that the AgNPs synthesized in this study had enough anti-pathogenic potential and could inexpensively and safely be used as a promising alternative to agrochemicals. Moreover, the findings observed in this study is likely to serve as an important indicator for the development of effective nano-control agents which in effect would help to manage some deadly phyto-pathogens capable of causing heavy losses to agricultural production systems.

GRAPHICAL ABSTRACT

Effective inhibition of phytopathogenic microbes by eco-friendly neem leaf extract mediated silver nanoparticles (AgNPs).

The phytoremediation efficiency of Eucalyptus globulus treated by static magnetic fields before sowing

Eucalyptus globulus pre-treated by static magnetic fields of 30, 60, 120, 150 and 400 mT (mT) before sowing were used in a 45-day experiment to remediate soil containing Cd, Hg, Pb, Zn, Cr and Cu. The influence of magnetic fields on its remediation efficiency was evaluated. Magnetic fields with strength of 30, 60, 120 and 150 mT increased the biomass yield of the species by 3.1, 19.4, 48.1 and 60.9%, respectively, while 400 mT decreased the yield by 16.7%. Comparing with the control exposed only to the earth's geomagnetic field, all plants pre-treated by static magnetic field had significantly higher metal concentrations with the highest values achieved in the field of 400 mT. Higher transpiration rate of the plants along with exposure to static magnetic fields induced lower soil moisture content and was beneficial to environmental control because it could reduce the leachate during the phytoremediation process. Among all static magnetic field treatments, 150 mT was the best to improve the phytoremediation and alleviate the environmental risk, which shortened the time to purify Cd, Pb and Cu by 27.8-73.2%, 27.3-74.7% and 2.5-50.6%, respectively and intercepted 31.6-86.1% of the leachate. Therefore, static magnetic field with appropriate intensity is a suitable candidate to improve phytoremediation efficiency through enhancing the biomass production, toxin uptake and leachate interception.

Biogenic phytochemicals (cassinopin and isoquercetin) capped copper nanoparticles (ISQ/CAS@CuNPs) inhibits MRSA biofilms

Purified glycosides, Isoquercetin and Cassinopin from Crotalaria candicans were selected for the synthesis of biogenic copper nanoparticles (CuNPs).The designed biogenic CuNPs was characterized and when evaluated against panel of gram negative and positive bacteria, the biogenic CuNPs were found to be more effective against methicillin resistant Staphylococcus aureus (MRSA). Antibacterial, anti-biofilm effects and time kill studies confirmed the ability of biogenic CuNPs to curtail MRSA. Scanning electron microscopy, Crystal violet staining and fluorescent live-dead imaging showed that treatment with sub lethal levels of glycoside capped CuNPs resulted in greater than 50% decline in biofilm formation by MRSA, which implies that anti-biofilm effect of biogenic CuNPs is not dependent on antibacterial effect. Alizarin red assay implied that prolonged treatment of biogenic CuNPs in presence of MRSA, releases Cu(II) ions and hence antibiofilm effect is primarily mediated by NP and is not due to released Cu(II) ion. The NPs caused altered membrane permeability and reduced surface hydrophobicity, thus accounting for its antibiofilm effect.

A Simple Electrochemical Route to Access Amorphous Co-Ni Hydroxide for Non-enzymatic Glucose Sensing

Among the numerous transition metal hydroxide materials, cobalt- and nickel-based hydroxides have been extensively studied for their excellent electrochemical performances such as non-enzymatic electrochemical sensors. Binary cobalt-nickel hydroxide has received extensive attention for its exceptionally splendid electrochemical behaviors as a promising glucose sensor material. In this work, we report the synthesis of three-dimensional amorphous Co-Ni hydroxide nanostructures with homogeneous distribution of elements via a simple and chemically clean electrochemical deposition method. The amorphous Co-Ni hydroxide, as a non-enzymatic glucose sensor material, exhibits a superior biosensing performance toward glucose detection for its superior electron transfer capability, high specific surface area, and abundant intrinsic redox couples of Ni2+/Ni3+ and Co2+/Co3+/Co4+ ions. The as-synthesized amorphous Co-Ni hydroxide holds great potential in glucose monitoring and detection as non-enzymatic glucose sensors with high sensitivity 1911.5 μA mM-1 cm-2 at low concentration, wide linear range of 0.00025-1 mM and 1-5 mM, low detection limit of 0.127 μM, super long-term stability, and excellent selectivity in 0.5 M NaOH solution.

Antimicrobial and antibiofilm activity of biopolymer-Ni, Zn nanoparticle biocomposites synthesized using R. mucilaginosa UANL-001L exopolysaccharide as a capping agent

Introduction: Global increase in the consumption of antibiotics has induced selective stress on wild-type microorganisms, pushing them to adapt to conditions of higher antibiotic concentrations, and thus an increased variety of resistant bacterial strains have emerged. Metal nanoparticles synthesized by green methods have been studied and proposed as potential antimicrobial agents against both wild-type and antibiotic-resistant strains; in addition, exopolysaccharides have been used as capping agent of metal nanoparticles due to their biocompatibility, reducing biological risks in a wide variety of applications. Purpose: In this work, we use an exopolysaccharide, from Rhodotorula mucilaginosa UANL-001L, an autochthonous strain from the Mexican northeast, as a capping agent in the synthesis of Zn, and Ni, nanoparticle biopolymer biocomposites. Materials and methods: To physically and chemically characterize the synthesized biocomposites, FT-IR, UV-Vs, TEM, SAED and EDS analysis were carried out. Antimicrobial and antibiofilm biological activity were tested for the biocomposites against two resistant clinical strains, a Gram-positive Staphylococcus aureus, and a Gram-negative Pseudomonas aeruginosa. Antimicrobial activity was determined using a microdilution assay whereas antibiofilm activity was analyzed through crystal violet staining. Results: Biocomposites composed of exopolysaccharide capped Zn and Ni metal nanoparticles were synthesized through a green synthesis methodology. The average size of the Zn and Ni nanoparticles ranged between 8 and 26 nm, respectively. The Ni-EPS biocomposites showed antimicrobial and antibiofilm activity against resistant strains of Staphylococcus aureus and Pseudomonas aeruginosa at 3 and 2 mg/mL, respectively. Moreover, Zn-EPS biocomposites showed antimicrobial activity against resistant Staphylococcus aureus at 1 mg/mL. Both biocomposites showed no toxicity, as renal function showed no differences between treatments and control in the in vivo assays with male rats tests in this study at a concentration of 24 mg/kg of body weight. Conclusion: The exopolysaccharide produced by Rhodotorula mucilaginosa UANL-001L is an excellent candidate as a capping agent in the synthesis of biopolymer-metal nanoparticle biocomposites. Both Ni and Zn-EPS biocomposites demonstrate to be potential contenders as novel antimicrobial agents against both Gram-negative and Gram-positive clinically relevant resistant bacterial strains. Moreover, Ni-EPS biocomposites also showed antibiofilm activity, which makes them an interesting material to be used in different applications to counterattack global health problems due to the emergence of resistant microorganisms.

Zinc-Doped Copper Oxide Nanocomposites Inhibit the Growth of Pancreatic Cancer by Inducing Autophagy Through AMPK/mTOR Pathway

Zinc doped copper oxide nanocomposites (Zn-CuO NPs) is a novel doped metal nanomaterial synthesized by our group using the sonochemical method. Our previous studies have shown that Zn-CuO NPs could inhibit cancer cell proliferation by inducing apoptosis via ROS-mediated pathway. In the present study, we studied the anticancer effect of Zn-CuO NPs on human pancreatic cancer cells. MTS assay revealed that Zn-CuO NPs was able to inhibit cancer cell growth. TEM, flow cytometry and fluorescence microscope analysis showed that Zn-CuO NPs induced autophagy significantly; the number of autophagosomes increased obviously in cells treated with Zn-CuO NPs. Western blot analysis revealed that treatment with the NPs resulted in activation of AMPK/mTOR pathway in both AsPC-1 and MIA Paca-2 cells in dose dependent manners. Moreover, in the presence of AMPK activator AMPKinone, the protein level of p-AMPK, p-ULK1, Beclin-1 and LC3-II/LC3-I increased, while the protein expression of p-AMPK, p-ULK1, Beclin-1 and LC3-II/LC3-I decreased in the presence of AMPK inhibitor Compound C. In vivo study using xenograft mice revealed that Zn-CuO NPs significantly inhibited tumor growth with low toxicity. Our study confirms that Zn-CuO NPs inhibit the tumor growth both in vitro and in vivo for pancreatic cancer. AMPK/mTOR pathway plays an important role in the NPs induced inhibition of tumor growth.

Bacterial toxicity of biomimetic green zinc oxide nanoantibiotic: insights into ZnONP uptake and nanocolloid-bacteria interface

This study was aimed to fill the critical gap of knowledge regarding the interaction between green zinc oxide nanoparticles (ZnONPs) and bacterial interface. Wurtzite phase ZnONPs with a band gap energy of 3.28 eV were produced by exploiting a simple and green biosynthesis method using an inexpensive precursor of A. indica leaf extract and zinc nitrate. ZnONPs were characterized using UV-Vis spectroscopy, XRD, FTIR, SEM, EDX, DLS, TEM, and zeta-potential analysis. The primary size obtained was 26.3 nm (XRD) and 33.5 ± 6.5 nm (TEM), whereas, the secondary size was found to be 287 ± 5.2 nm with -32.8 ± 1.8 mV ζ-potential denoting the physical colloid chemistry of ZnONPs. Crystallinity and the spherical morphology of ZnONPs were also evident with some sort of particle agglomeration. ZnONPs retained plant functional groups endorsing their hydrophilic character. The antibacterial and antibiofilm activity of ZnONPs was significant (p ≤ 0.05) and the MIC/MBC against most frequent clinical isolates of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus ranged from 0.5 to 1.0 (MIC)/1.0 to 1.5 mg ml-1 (MBC). The dissolution of ZnONPs to Zn2+ ions in a nutrient medium increased as a result of interaction with the bacterial surface and metabolites. Substantial surface binding of ZnONPs followed by intracellular uptake disrupted the cell morphology and caused obvious injury to the cell membrane. Interrupted bacterial growth kinetics, loss of cell respiration, enhanced production of intracellular ROS, and the leakage of the cytoplasmic content unequivocally suggested a strong interaction of ZnONPs with the exterior cell surface and intracellular components, eventually leading to cell death and destruction of biofilms. Overall, the results elucidated eco-friendly production of ZnONPs expressing a prominent interfacial correlation with bacteria and hence, prospecting the use of green ZnONPs as effective nanoantibiotics.

Acute and subacute oral toxicity of copper oxide nanoparticles in female albino Wistar rats

The extensive use of copper oxide nanoparticles (CuO-NPs) in various industries and their wide range of applications have led to their accumulation in different ecological niches of the environment. This excess exposure raises the concern about its potential toxic effects on various organisms including humans. However, the hazardous potential of CuO-NPs in the literature is elusive, and it is essential to study its toxicity in different biological models. Hence, we have conducted single acute dose (2000 mg/kg) and multiple dose subacute (30, 300 and 1000 mg/kg daily for 28 days) oral toxicity studies of CuO-NPs in female albino Wistar rats following OECD guidelines 420 and 407 respectively. Blood analysis, tissue aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and acetylcholinesterase, superoxide dismutase, catalase, lipid malondialdehyde and reduced glutathione assays, and histopathology of the tissues were carried out. The higher dose treatments of the acute and subacute study caused significant alterations in biochemical and antioxidant parameters of the liver, kidney and brain tissues of the rat. In addition, histopathological evaluation of these three organs of treated rats showed significantly high abnormalities in their histoarchitecture when compared to control rats. We infer from the results that the toxicity observed in the liver, kidney and brain of treated rats could be due to the increased generation of reactive oxygen species by CuO-NPs.

Oxidative stress generated at nickel oxide nanoparticle interface results in bacterial membrane damage leading to cell death

Metal oxide nanoparticles (NPs) have shown enhanced antibacterial effects against many bacteria.

Toxicity assessment of metal oxide nano-pollutants on tomato (Solanum lycopersicon): A study on growth dynamics and plant cell death

The present study for the first time demonstrated the interactions of metal oxide (MO) nano-pollutants (CuO and Al₂O₃-NPs) with tissues and cellular DNA of tomato plants grown in soil sand: silt: clay (667:190:143) and Hoagland-hydroponic system and assessed the hazardous effects of NPs on cell physiology and biochemistry. Results of SEM equipped with EDX revealed attachment of variably shaped CuO-NPs (18 nm) and Al₂O₃-NPs (21 nm) on roots, and internalization followed by translocation in plants by ICP-MS and TEM. Significant variations in foliage surface area, chlorophyll, proteins, LPO, and antioxidant enzymes were recorded. Roots and shoots accumulated 225.8 ± 8.9 and 70.5 ± 4 μgAl g^-1 DW, whereas Cu accumulation was 341.6 ± 14.3 (roots) and 146.9 ± 8.1 μg g^-1 DW (shoots) which was significant (p ≤ 0.0005) as compared to control. The total soluble protein content in roots, shoots, and leaves collected from Al₂O₃-NPs treated plants increased by 120, 80, and 132%, respectively while in CuO-NPs treatments, the increase was 68 (roots), 36 (shoots), and 86% (leaves) over control. The level of antioxidant enzymes in plant tissues was significantly (p ≤ 0.05) higher at 2000 μg ml^-1 of MONPs over control. A dose-dependent increase in reactive oxygen species (ROS), biphasic change of lower and higher fluorescence in mitochondria due to dissipation of mitochondrial membrane potential (ΔΨm) and membrane defects using propidium iodide were observed. Comparatively, CuO-NPs induced higher toxicity than Al₂O₃-NPs. Perceptible changes in proteins (amide-I & II), cellulose, glucose, galactose and other carbohydrates were observed under FT-IR. The binding studies with TmDNA showed fluorescence quenching of EtBr-TmDNA and acridine orange-TmDNA complex only by CuO-NPs with -ΔG and +ΔH and +ΔS values. However, Al₂O₃-NPs induced lesser change in TmDNA conformation. Conclusively, the results are novel in better demonstrating the mechanistic basis of nano-phyto-toxicity and are important which could be used to develop strategies for safe disposal of Al₂O₃-NPs and CuO-NPs.

Prospects of using nanotechnology for food preservation, safety, and security

The rapid development of nanotechnology has transformed many domains of food science, especially those that involve the processing, packaging, storage, transportation, functionality, and other safety aspects of food. A wide range of nanostructured materials (NSMs), from inorganic metal, metal oxides, and their nanocomposites to nano-organic materials with bioactive agents, has been applied to the food industry. Despite the huge benefits nanotechnology has to offer, there are emerging concerns regarding the use of nanotechnology, as the accumulation of NSMs in human bodies and in the environment can cause several health and safety hazards. Therefore, safety and health concerns as well as regulatory policies must be considered while manufacturing, processing, intelligently and actively packaging, and consuming nano-processed food products. This review aims to provide a basic understanding regarding the applications of nanotechnology in the food packaging and processing industries and to identify the future prospects and potential risks associated with the use of NSMs.

Cellular destruction, phytohormones and growth modulating enzymes production by Bacillus subtilis strain BC8 impacted by fungicides

In vitro experiments were performed to ascertain the impact of kitazin, hexaconazole, metalaxyl and carbendazim on growth behaviour, enzymatic profile, ultrastructure, cell permeability and bioactive molecules of phosphate-solubilizing bacterium. Strain BC8 isolated from Brassica oleracea rhizosphere was characterized and identified as Bacillus subtilis by 16S rDNA sequencing (Accession no. MG028650) technique. Strain BC8 was unambiguously chosen due to its high tolerance capability to various fungicides and substantial production of plant growth regulators. The biomarker enzymatic assays (lipid peroxidation, lactate dehydrogenase) and oxidative stress (catalase) induced by fungicides exhibited significant (p < 0.05) toxicity of fungicides toward strain BC8. Fungicides caused the cellular/ultrastructural damage and reduced the viability of strain BC8 as clearly revealed under scanning (SEM), high resolution transmission (HR-TEM) and confocal laser scanning (CLSM) microscopy. As the concentration of fungicides increased, a gradual drop in the plant growth promoting traits of B. subtilis strain BC8 was observed. Kitazin at 2400 μg mL^-1, hexaconazole at 1500 μg mL^-1, metalaxyl at 1200 μg mL^-1 and carbendazim at 1200 μg mL^-1decreased the IAA production by 35 (48.3 μg mL^-1), 27 (51.5 μg mL^-1), 39 (43.6 μg mL^-1) and 47% (37.3 μg mL^-1), respectively, over control (71.3 μg mL^-1), while, α-ketobutyrate was declined by 51 (29.6), 56 (26.2), 61 (22.8) and 68 (19)%, respectively, over untreated control (59.9 mg protein^-1 h^-1). Also, with increase in the concentration of fungicides there was a significant decrease in plant nutrient (P); the maximum being (19.6 μg mL^-1) observed at 1500 μg mL^-1 hexaconazole with consequent drop in pH (from pH 6.4 to 4.2). The current findings clearly suggest that despite injury, B. subtilis maintained secreting active biomolecules and this property makes this organism truly indispensable for enhancing crop production under fungicide stressed conditions.

Application of cationic polymer micelles for the dispersal of bacterial biofilms

Contamination of surfaces in hospitals and food industry by bacterial biofilms is a serious health risk. Of concern is their resistance to routine antibacterials and disinfectants. This requires the development of novel approaches to biofilm detachment. The study evaluates the effectiveness of cationic polymer micelles (CPMs) against pre-formed biofilms. CPMs based on different polycations were used. The hydrodynamic radius of the particles ranged from 16 to 360 nm. Biofilms of Escherichia coli 420, Pseudomonas aeruginosa PAO1, Staphylococcus aureus 29213 and Bacillus subtilis 168 were cultivated for 24 h then the pre-formed biofilms were treated with the CPMs for 2, 4 or 6 h. Biofilm biomass was evaluated by the crystal violet assay, and live/dead fluorescence test was applied for bacterial viability. The ability of CPMs to interact with pre-formed biofilms of the model strains was evaluated. We observed that the most effective CPMs were those based on poly(2-(dimethylamino)ethyl methacrylate) copolymers which reduced the biofilm biomass three- to four-fold compared with the treatment of the biofilm with water. Significantly reduced vitality of the bacteria in the biofilms was registered by the live/dead stain. The results indicate the applicability of the CPMs for disinfection of biofilm-contaminated surfaces and the treatment of wounds.

Bactericidal Properties of Plants-Derived Metal and Metal Oxide Nanoparticles (NPs)

Nanoparticles (NPs) are nano-sized particles (generally 1–100 nm) that can be synthesized through various methods. The wide range of physicochemical characteristics of NPs permit them to have diverse biological functions. These particles are versatile and can be adopted into various applications, particularly in biomedical field. In the past five years, NPs’ roles in biomedical applications have drawn considerable attentions, and novel NPs with improved functions and reduced toxicity are continuously increasing. Extensive studies have been carried out in evaluating antibacterial potentials of NPs. The promising antibacterial effects exhibited by NPs highlight the potential of developing them into future generation of antimicrobial agents. There are various methods to synthesize NPs, and each of the method has significant implication on the biological action of NPs. Among all synthetic methods, green technology is the least toxic biological route, which is particularly suitable for biomedical applications. This mini-review provides current update on the antibacterial effects of NPs synthesized by green technology using plants. Underlying challenges in developing NPs into future antibacterials in clinics are also discussed at the present review.

Glyphosate induced toxicity to chickpea plants and stress alleviation by herbicide tolerant phosphate solubilizing Burkholderia cepacia PSBB1 carrying multifarious plant growth promoting activities

In this study, strain PSBB1 isolated from Vicia faba rhizosphere was identified as Burkholderia cepacia, by 16S rDNA sequence analysis and characterized. Strain PSBB1 tolerated glyphosate up to 3200 μg ml-1 and produced IAA (81.6 μg ml-1), ACC deaminase (69.3 mg-1 protein h-1), SA (39.3 μg ml-1) and 2,3-DHBA (26.6 μg ml-1), solubilized insoluble P (50.8 μg ml-1) and secreted 29.4 μg ml-1 exopolysaccharides, which decreased with increasing concentrations of glyphosate. Cell damage following glyphosate application was visible under SEM and CLSM. The phytotoxicity of glyphosate on chickpea was variable but significant. B. cepacia mitigated toxicity and enhanced the size, dry matter, symbiosis, seed attributes and nutritional contents of chickpea. Further, B. cepacia strain PSBB1 declined the levels of CAT, POD, APX and GPX and MDA contents at 4332 μg kg-1 soil glyphosate. Proline also increased under glyphosate stress but declined in B. cepacia inoculated plants. The ability to tolerate higher concentration of glyphosate, the capacity to secrete plant growth regulators even under herbicide stress and potential to reduce the level of proline and antioxidant enzymes makes B. cepacia as an interesting choice for enhancing chickpea production in soils contaminated even with herbicides.

Chromosomal aberrations, cell suppression and oxidative stress generation induced by metal oxide nanoparticles in onion (Allium cepa) bulb

In this work, we assess the phytotoxicity of various-sized metal oxide nanoparticles on cell cycle progression and induction of oxidative stress in onions.

Green Adeptness in the Synthesis and Stabilization of Copper Nanoparticles: Catalytic, Antibacterial, Cytotoxicity, and Antioxidant Activities

Copper nanoparticles (CuNPs) are of great interest due to their extraordinary properties such as high surface-to-volume ratio, high yield strength, ductility, hardness, flexibility, and rigidity. CuNPs show catalytic, antibacterial, antioxidant, and antifungal activities along with cytotoxicity and anticancer properties in many different applications. Many physical and chemical methods have been used to synthesize nanoparticles including laser ablation, microwave-assisted process, sol-gel, co-precipitation, pulsed wire discharge, vacuum vapor deposition, high-energy irradiation, lithography, mechanical milling, photochemical reduction, electrochemistry, electrospray synthesis, hydrothermal reaction, microemulsion, and chemical reduction. Phytosynthesis of nanoparticles has been suggested as a valuable alternative to physical and chemical methods due to low cytotoxicity, economic prospects, environment-friendly, enhanced biocompatibility, and high antioxidant and antimicrobial activities. The review explains characterization techniques, their main role, limitations, and sensitivity used in the preparation of CuNPs. An overview of techniques used in the synthesis of CuNPs, synthesis procedure, reaction parameters which affect the properties of synthesized CuNPs, and a screening analysis which is used to identify phytochemicals in different plants is presented from the recent published literature which has been reviewed and summarized. Hypothetical mechanisms of reduction of the copper ion by quercetin, stabilization of copper nanoparticles by santin, antimicrobial activity, and reduction of 4-nitrophenol with diagrammatic illustrations are given. The main purpose of this review was to summarize the data of plants used for the synthesis of CuNPs and open a new pathway for researchers to investigate those plants which have not been used in the past. Graphical abstract Proposed Mechanism for Antibacterial activity of copper nanoparticles.