Glycation reduces the binding dynamics of aflatoxin B1 to human serum albumin: a comprehensive spectroscopic and computational investigation.

Aflatoxin B1 (AFB1), a potent mutagen, is synthesized by Aspergillus parasiticus and Aspergillus flavus. Human serum albumin (HSA) is a globular protein with diverse roles. As AFB1 is ingested with food and is transported in the body via blood, it becomes pertinent to comprehend the effect of the binding of this toxin on the structure and conformation of HSA, which may help to get insight into the toxic effect of the exposure of the mycotoxin. In this study, multi-spectroscopic approaches have been used to evaluate the binding efficiency of AFB1 with both the native HSA (nHSA) and the glycated HSA (gHSA). Steady-state fluorescence spectroscopy reveals the static type of fluorescence quenching in the fluorescence emission spectra of nHSA and gHSA in the presence of AFB1. The binding constant (Kb) is calculated to be 6.88 × 104 M-1 for nHSA, while a reduced Kb value of 2.95 × 104 M-1 has been obtained for gHSA. The circular dichroism study confirms the change in the secondary structure of nHSA and gHSA in the presence of AFB1, followed by alterations in the melting temperature (Tm) of nHSA and gHSA. In silico computational findings envisaged the amino acid residues and bonds involved in the binding of nHSA and gHSA with AFB1. The comprehensive study analyzes the binding effectiveness of AFB1 with nHSA and gHSA and shows reduced binding of AFB1 to gHSA.Communicated by Ramaswamy H. Sarma.

As revealed by UV-absorption spectroscopy, the hyperchromic effect was more prominent in nHSA than gHSA in the presence of AFB₁.The binding constant (K_b) obtained for the nHSA-AFB₁ complex was 6.88 × 10⁴ M^−1, and the gHSA-AFB₁ complex yielded K_b value of 2.95 × 10⁴ M⁻¹.Negative enthalpy change (ΔH) and entropy change (ΔS) suggested hydrogen bonding and van der Waals interaction as stabilizing forces of nHSA-AFB₁ and gHSA-AFB₁ complex.Site markers displacement assay suggested Sudlow's site I as the binding site for AFB₁ in nHSA and gHSA.Circular dichroism study showed that AFB₁ induced secondary structural changes in nHSA and gHSA.Melting temperature (T_m) increased in nHSA and decreased in gHSA in the presence of AFB₁.Molecular docking results confirmed Lys-195, Arg-222 and Arg-257 as hydrogen bonding residues in the nHSA-AFB₁ complex and Arg-222 and Lys-199 residues were involved in hydrogen bonding in the gHSA-AFB₁ complex.

Titanium Dioxide Nanoparticles Induce Inhibitory Effects against Planktonic Cells and Biofilms of Human Oral Cavity Isolates of Rothia mucilaginosa, Georgenia sp. and Staphylococcus saprophyticus.

Multi-drug resistant (MDR) bacterial cells embedded in biofilm matrices can lead to the development of chronic cariogenesis. Here, we isolated and identified three Gram-positive MDR oral cocci, (1) SJM-04, (2) SJM-38, and (3) SJM-65, and characterized them morphologically, biochemically, and by 16S rRNA gene-based phylogenetic analysis as Georgenia sp., Staphylococcus saprophyticus, and Rothia mucilaginosa, respectively. These three oral isolates exhibited antibiotic-resistance against nalidixic acid, tetracycline, cefuroxime, methicillin, and ceftazidime. Furthermore, these Gram positive MDR oral cocci showed significant (p < 0.05) variations in their biofilm forming ability under different physicochemical conditions, that is, at temperatures of 28, 30, and 42 °C, pH of 6.4, 7.4, and 8.4, and NaCl concentrations from 200 to 1000 µg/mL. Exposure of oral isolates to TiO2NPs (14.7 nm) significantly (p < 0.05) reduced planktonic cell viability and biofilm formation in a concentration-dependent manner, which was confirmed by observing biofilm architecture by scanning electron microscopy (SEM) and optical microscopy. Overall, these results have important implications for the use of tetragonal anatase phase TiO2NPs (size range 5-25 nm, crystalline size 13.7 nm, and spherical shape) as an oral antibiofilm agent against Gram positive cocci infections. We suggest that TiO2NPs pave the way for further applications in oral mouthwash formulations and antibiofilm dental coatings.

Differential responses of maize (Zea mays) at the physiological, biomolecular, and nutrient levels when cultivated in the presence of nano or bulk ZnO or CuO or Zn2+ or Cu2+ ions.

Expanding applications of metal-based nanoparticles (NPs) in industry and agriculture have influenced agro-ecosystems. However, relatively little is known about the bioaccumulation, distribution, and phytotoxicity of ZnO-NPs, CuO-NPs, ZnO-bulk, CuO-bulk, Zn2+, or Cu2+ in maize. Plants were exposed to 0.05-2 mg ml-1 or g-1 of six tested materials in agar (7 days) in hydroponic medium (20 days), or sandy-clay-loam soil (20 or 40 days). Seed germination, emergence and lengths of plumules, principal and seminal roots were significantly inhibited by ZnO-NPs, CuO-NPs, Zn2+, and Cu2+. Toxicity was more pronounced in hydroponic culture than in soil, and perceptible alterations in biomolecules were evident. ICP-MS analysis exhibited progressive uptake of metals while morphological, elemental, and surface/deeper scanning showed translocation and distribution of NPs in tissues. Tested materials induced enhanced superoxide radical production, lipid peroxidation, and antioxidant enzymes and proline levels. Exposure significantly reduced P-accumulation, photosynthesis, and protein production. Zn2+ and Cu2+ were found to be more toxic than NPs. Compared to 20 days exposure in soil, toxicity slightly increased after 40 days. ZnO-NPs and CuO-NPs increased apoptotic sub-G1 population by 22.4% and 38%, respectively. These results provide a better understanding of the mechanistic aspects responsible for the nanotoxicities of ZnO- and CuO-NPs in maize.

Ampicillin-augmented Silver Nanoparticles for Synergistic Antimicrobial Response: A Promising Therapeutic Approach.

AIMS: Globally, scientists are working to find more efficient antimicrobial drugs to treat microbial infections and kill drug-resistant bacteria. BACKGROUND: Despite the availability of numerous antimicrobial drugs, bacterial infections still pose a serious threat to global health. A constant decline in the effectiveness of antibiotics owing to their repeated exposure as well as a short-lasting antimicrobial activity led to the demand for developing novel therapeutic agents capable of controlling microbial infections. OBJECTIVE: In this study, we report the antimicrobial activity of chemically synthesized silver nanoparticles (cAgNPs) augmented with ampicillin (amp) in order to increase antimicrobial response against Escherichia coli (gram -ve), Staphylococcus aureus (gram +ve) and Streptococcus mutans (gram +ve). METHODS: Nanostructure, colloidal stability, morphology and size of cAgNPs before and after functionalization were explored by UV-vis spectroscopy, FT-IR, zeta potential and TEM. The formation and functionalization of cAgNPs were confirmed from UV-vis spectroscopy and FT-IR patterns. From TEM, the average sizes of cAgNPs and cAgNP-amp were found to be 13 and 7.8 nm, respectively, and change in colloidal stability after augmentation was confirmed from zeta potential values. The antimicrobial efficacies of cAgNP-amp and cAgNPs against E. coli S. aureus and S. mutans were studied by determining Minimum Inhibitory Concentrations (MICs), zone of inhibition, assessment of viable and non-viable bacterial cells and quantitative assessment of biofilm. RESULTS & DISCUSSION: Our results revealed cAgNP-amp to be highly bactericidal compared to cAgNPs or amp alone. The nano-toxicity studies indicated cAgNP-amp to be less toxic compared to cAgNPs alone. CONCLUSION: This study manifested that cAgNPs show synergistic antimicrobial effects when they get functionalized with amp suggesting their application in curing long-term bacterial infections.

Cytotoxicity and genotoxicity of methomyl, carbaryl, metalaxyl, and pendimethalin in human umbilical vein endothelial cells.

Pesticides have adverse effects on the cellular functionality, which may trigger myriad of health consequences. However, pesticides-mediated toxicity in the endothelial cells (ECs) is still elusive. Hence, in this study, we have used human umbilical vein endothelial cells (HUVECs) as a model to quantify the cytotoxicity and genotoxicity of four pesticides (methomyl, carbaryl, metalaxyl, and pendimethalin). In the MTT assay, HUVECs exposed to methomyl, carbaryl, metalaxyl, and pendimethalin demonstrated significant proliferation inhibition only at higher concentrations (500 and 1000 µM). Likewise, neutral red uptake (NRU) assay also showed proliferation inhibition of HUVECs at 500 and 1000 µM by the four pesticides, confirming lysosomal fragility. HUVECs exposed to the four pesticides significantly increased the level of intracellular reactive oxygen species (ROS). Comet assay and flow cytometric data exhibited DNA damage and apoptotic cell death in HUVECs after 24 h of exposure with methomyl, metalaxyl, carbaryl, and pendimethalin. This is a first study on HUVECs signifying the cytotoxic-genotoxic and apoptotic potential of carbamate insecticides (methomyl and carbaryl), fungicide (metalaxyl), and herbicide (pendimethalin). Overall, these pesticides may affect ECs functions and angiogenesis; nonetheless, mechanistic studies are warranted from the perspective of vascular biology using in vivo test models.

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, Al2O3, 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.

Destruction of Cell Topography, Morphology, Membrane, Inhibition of Respiration, Biofilm Formation, and Bioactive Molecule Production by Nanoparticles of Ag, ZnO, CuO, TiO2, and Al2O3 toward Beneficial Soil Bacteria.

The unregulated discharge of nanoparticles (NPs) from various nanotechnology industries into the environment is expected to alter the composition and physiological functions of soil microbiota. Considering this knowledge gap, the impact of five NPs (Ag, ZnO, CuO, Al2O3, and TiO2) differing in size and morphology on growth behavior and physiological activity of Azotobacter chroococcum, Bacillus thuringiensis, Pseudomonas mosselii, and Sinorhizobium meliloti were investigated. Various biochemical and microscopic approaches were adopted. Interestingly, all bacterial strains were found sensitive to Ag-NPs and ZnO-NPs but showed tolerance toward CuO, Al2O3, and TiO2-NPs. The loss of cellular respiration due to NPs was coupled with a reduction in population size. ZnO-NPs at 387.5 µg mL-1 had a maximum inhibitory impact on A. chroococcum and reduced its population by 72%. Under Ag-NP stress, the reduction in IAA secretion by bacterial strains followed the order S. meliloti (74%) > P. mosselii (63%) > A. chroococcum (49%). The surface of bacterial cells had small- or large-sized aggregates of NPs. Also, numerous gaps, pits, fragmented, and disorganized cell envelopes were visible. Additionally, a treated cell surface appeared corrugated with depressions and alteration in cell length and a strong heterogeneity was noticed under atomic force microscopy (AFM). For instance, NPs induced cell roughness for P. mosselii followed the order 12.6 nm (control) > 58 nm (Ag-NPs) > 41 nm (ZnO-NPs). TEM analysis showed aberrant morphology, cracking, and disruption of the cell envelope with extracellular electron-dense materials. Increased permeability of the inner cell membrane caused cell death and lowered EPS production. Ag-NPs and ZnO-NPs also disrupted the surface adhering ability of bacteria, which varied with time and concentration of NPs. Conclusively, a plausible mechanism of NP toxicity to bacteria has been proposed to understand the mechanistic basis of ecological interaction between NPs and resourceful bacteria. These results also emphasize to develop strategies for the safe disposal of NPs.

Cymbopogon Citratus Functionalized Green Synthesis of CuO-Nanoparticles: Novel Prospects as Antibacterial and Antibiofilm Agents.

Chemically synthesized copper oxide nanoparticles (CuONPs) involve the generation of toxic products, which narrowed its biological application. Hence, we have developed a one-pot, green method for CuONP production employing the leaf extract of Cymbopogon citratus (CLE). Gas chromatography-mass spectrometry (GC-MS) analysis confirmed the capping of CuONPs by CLE esters (CLE-CuONPs). Fourier-transform infrared (FTIR) showed phenolics, sugars, and proteins mediated nucleation and stability of CLE-CuONPs. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed CLE-CuONPs between 11.4 to 14.5 nm. Staphylococcus aureus-1 (MRSA-1), Staphylococcus aureus-2 (MSSA-2) exposed to CLE-CuONPs (1500 µg/mL) showed 51.4%, 32.41% survival, while Escherichia coli-336 (E. coli-336) exposed to 1000 µg/mL CLE-CuONPs showed 45.27% survival. Scanning electron microscopy (SEM) of CLE-CuONPs treated E. coli-336, MSSA-2 and MRSA-1 showed morphological deformations. The biofilm production by E. coli-336 and MRSA-1 also declined to 33.0 ± 3.2% and 49.0 ± 3.1% at 2000 µg/mL of CLE-CuONPs. Atomic absorption spectroscopy (AAS) showed 22.80 ± 2.6%, 19.2 ± 4.2%, and 16.2 ± 3.6% accumulation of Cu2+ in E. coli-336, MSSA-2, and MRSA-1. Overall, the data exhibited excellent antibacterial and antibiofilm efficacies of esters functionalized CLE-CuONPs, indicating its putative application as a novel nano-antibiotic against multi drug resistance (MDR) pathogenic clinical isolates.

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.

Myristica fragrans bio-active ester functionalized ZnO nanoparticles exhibit antibacterial and antibiofilm activities in clinical isolates.

We provide a novel one-step/one-pot bio-inspired method of synthesis for Myristica fragrans leaf ester (MFLE) capped­zinc oxide nanoparticles (MFLE-ZnONPs). Antibacterial and antbiofilm efficacies of MFLE-ZnONPs were tested against the multi-drug resistant (MDR) Escherichia coli (E. coli-336), methicillin-resistant Staphylococcus aureus (MRSA-1) and methicillin-sensitive (MSSA-2) clinical isolates. Antibacterial screening using well diffusion assay revealed the cytotoxicity of MFLE-ZnONPs in the range of 500-2000 µg/ml. MFLE-ZnONPs significantly increased the zone of growth inhibition of E. coli-336 (17.0 ±â€¯0.5 to 19.25 ±â€¯1.0 mm), MSSA-2 (16.75 ±â€¯0.8 to 19.0 ±â€¯0.7 mm) and MRSA-1 (16.25 ±â€¯1.0 to 18.25 ±â€¯0.5 mm), respectively. The minimum inhibitory concentration (MIC) and minimum bactericidal concentrations (MBC) against E. coli-336, MRSA-1 and MSSA-2 were found to be 1500, 1000 and 500 µg/ml, and 2500, 2000 and 1500 µg/ml, respectively. A time and dose dependent reduction in the cell proliferation were also found at the respective MICs of tested strains. Scanning electron microscopy (SEM) of MFLE-ZnONPs-treated strains exhibited cellular damage via loss of native rod and coccoid shapes because of the formation of pits and cavities. E. coli-336 and MRSA-1 strains at their MICs (1500 and 1000 µg/ml) sharply reduced the biofilm production to 51% and 24%. The physico-chemical characterization via x-ray diffraction (XRD) ascertained the crystallinity and an average size of MFLE-ZnONPs as 48.32 ±â€¯2.5 nm. Gas chromatography-mass spectroscopy (GC-MS) analysis of MFLE-ZnONPs unravelled the involvement of two bio-active esters (1) butyl 3-oxobut-2-yl ester and (2) α-monoolein) as surface capping/stabilizing agents. Fourier transform infrared (FTIR) analysis of MFLE and MFLE-ZnONPs showed the association of amines, alkanes, aldehydes, amides, carbonyl and amines functional groups in the corona formation. Overall, our data provide novel insights on the rapid development of eco-friendly, cost-effective bio-synthesis of MFLE-ZnONPs, showing their putative application as nano-antibiotics against MDR clinical isolates.

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).

Comparative in situ ROS mediated killing of bacteria with bulk analogue, Eucalyptus leaf extract (ELE)-capped and bare surface copper oxide nanoparticles.

This study demonstrates a simple one-pot green method for biosynthesis of terpenoids encapsulated copper oxide nanoparticles (CuONPs) using aqueous leaf extract of Eucalyptus globulus (ELE), as reducing, dispersing, and stabilizing agent. Indeed, the greater attachment and internalization of ELE-CuONPs in Gram-positive and -negative biofilm producing clinical bacterial isolates validated the hypothesis that terpenoids encapsulated CuONPs are more stable and effective antibacterial and antibiofilm agent vis-à-vis commercially available nano and micro sized analogues. Gas chromatography-mass spectroscopy (GC-MS) analysis of pristine ELE identified 17 types of terpenoids based on their mass-to-charge (m/z) ratios. Amongst them four bioactive terpenoids viz. terpineols, 2,6-octadienal-3,7-dimethyl, benzamidophenyl-4-benzoate and ß-eudesmol were found associated with the CuONPs as ELE-cap, and most likely involved in the nucleation and stabilization of ELE-CuONPs. Further, the Fourier transformed infrared (FTIR) analysis of ELE-CuONPs also implicated other functional biomolecules like proteins, sugars, alkenes, etc. with ELE terpenoids corona. Flow cytometric (FCM) data exhibited significantly enhanced intracellular uptake propensity of terpenoids encapsulated ELE-CuONPs and accumulation of intracellular reactive oxygen species (ROS), which ensued killing of planktonic cells of extended spectrum ß-lactamases (ESßL) producing Escherichia coli-336 (E. coli-336), Pseudomonas aeruginosa-621 (P. aeruginosa-621) and methicillin-resistant Staphylococcus aureus-1 (MRSA-1) clinical isolates compared to the bare surface commercial nano-CuO and bulk sized CuO. The study for the first-time demonstrated the (i) differential bio-nano interface activities due to ELE surface and varied cell wall composition of test bacterial isolates, (ii) antibacterial effect and biofilm inhibition due to disruption of proteins involved in adhesion and biofilm formation triggered by CuONPs induced intracellular oxidative stress, and (iii) indigenous terpenoids-capped bio-inspired CuONPs are more stable and effective antibacterial and antibiofilm agent as compared with commercially available nano-CuO and bulk-CuO.

ARSACS as a Worldwide Disease: Novel SACS Mutations Identified in a Consanguineous Family from the Remote Tribal Jammu and Kashmir Region in India.

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a rare neurodegenerative disorder characterized by the triad of early-onset cerebellar ataxia, peripheral sensorimotor neuropathy, and lower limb spasticity. Here, we present a 28-year-old male patient with symptoms of ARSACS and mild intellectual disability from a consanguineous family of tribal J&K, India. Whole exome sequencing unraveled a novel homozygous frameshift SACS mutation (Cys2869ValfsTer15) in the patient. In addition to the well-established ARSACS imaging features, MRI revealed T2 hyperintense rim around the thalami ("bithalamic stripes") demonstrating that this feature might serve as an additional supportive diagnostic imaging marker for ARSACS. Moreover, retinal nerve fiber layer thickening which has recently been proposed as a diagnostic biomarker for ARSACS was present on routine optic coherence tomography (OCT) also in this patient, indicating that it might indeed present a relatively universal diagnostic biomarker for ARSACS. In sum, our findings extend the geographical distribution of ARSACS to even very remote tribal regions in Asia (such as the Rajouri region of J&K, India) and extend the mutational and imaging spectrum of ARSACS. They provide further support that brain imaging and OCT markers might serve as diagnostic biomarkers for ARSACS in patients with novel SACS mutations, applicable even in remote regions of the world to identify and confirm ARSACS disease.

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.

Understanding the phyto-interaction of heavy metal oxide bulk and nanoparticles: evaluation of seed germination, growth, bioaccumulation, and metallothionein production.

The fast-growing use of nano-based products without proper care has led to a major public health concern. Nanomaterials contaminating the environment pose serious threat to the productivity of plants and via food chain to human health. Realizing these, four vegetable crops, radish, cucumber, tomato, and alfalfa, were exposed to varying concentrations of heavy metal oxide (TiO2, ZnO, Al2O3 and CuO) submicron or bulk (BPs) and nanoparticles (NPs) to assess their impact on relative seed germination (RSG), seed surface adsorption, root/shoot tolerance index (RTI/STI), bioaccumulation, and metallothioneins (MTs) production. The results revealed a clear inhibition of RSG, RTI, and STI, which, however, varied between species of metal-specific nanoparticles and plants. SEM and EDX analyses showed significant adsorption of MONP agglomerates on seed surfaces. The concentration of metals detected by EDX differed among vegetables. Among the metals, Al, Cu, Ti, and Zn were found maximum in alfalfa (12.46%), tomato (23.2%), cucumber (6.32%) and radish (21.74%). Of the four metal oxides, ZnO was found most inhibitory to all vegetables and was followed by CuO. The absorption/accumulation of undesirable levels of MONPs in seeds and seedlings differed with variation in dose rates, and was found to be maximum (1748-2254 µg g-1 dry weight) in ZnO-NPs application. Among MONPs, the uptake of TiO2 was minimum (2 to 140 µg g-1) in radish seedlings. The concentration of MTs induced by ZnO-NPs, ZnO-BPs, and CuO-NPs ranged between 52 and 136 µ mol MTs g-1 FW in vegetal organs. Conclusively, the present findings indicated that both the nanosize and chemical composition of MONPs are equally dangerous for vegetable production. Hence, the accumulation of MONPs, specifically ZnO and CuO, in edible plant organs in reasonable amounts poses a potential environmental risk which, however, requires urgent attention to circumvent such toxic problems.

Anticancer Potential of Green Synthesized Silver Nanoparticles Using Extract of Nepeta deflersiana against Human Cervical Cancer Cells (HeLA).

In this study, silver nanoparticles (AgNPs) were synthesized using aqueous extract of Nepeta deflersiana plant. The prepared AgNPs (ND-AgNPs) were examined by ultraviolet-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), and energy dispersive spectroscopy (EDX). The results obtained from various characterizations revealed that average size of synthesized AgNPs was 33 nm and in face-centered-cubic structure. The anticancer potential of ND-AgNPs was investigated against human cervical cancer cells (HeLa). The cytotoxic response was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), neutral red uptake (NRU) assays, and morphological changes. Further, the influence of cytotoxic concentrations of ND-AgNPs on oxidative stress markers, reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP), cell cycle arrest and apoptosis/necrosis was studied. The cytotoxic response observed was in a concentration-dependent manner. Furthermore, the results also showed a significant increase in ROS and lipid peroxidation (LPO), along with a decrease in MMP and glutathione (GSH) levels. The cell cycle analysis and apoptosis/necrosis assay data exhibited ND-AgNPs-induced SubG1 arrest and apoptotic/necrotic cell death. The biosynthesized AgNPs-induced cell death in HeLA cells suggested the anticancer potential of ND-AgNPs. Therefore, they may be used to treat the cervical cancer cells.

Differential surface contact killing of pristine and low EPS Pseudomonas aeruginosa with Aloe vera capped hematite (α-Fe2O3) nanoparticles.

Biogenic hematite (α-Fe2O3) nanoparticles (NPs) of average size <10 nm were synthesized using green approach with Aloe vera extract (ALE). The aim of the study was to assess the protective effect of extracellular polymeric substances (EPS) against antibacterial and antibiofilm activities of ALE-α-Fe2O3NPs in normal EPS producers (pristine) and experimentally modified (low-EPS) Pseudomonas aeruginosa (P. aeruginosa) cells and the mechanism of cell killing. Formation of ALE-α-Fe2O3NPs has been validated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier-transformed infrared spectroscopy (FTIR) analysis. The FTIR data suggested the possible role OH group bearing organic compounds of ALE in metal reduction and nucleation of NPs. Gas Chromatography-Mass spectroscopy (GC-MS) analysis revealed the presence of oxime-methoxy-phenyl, ethanone 1-phenyl, hexadecanoic acid, cyclohexanol 2,6-dimethyl, tetracontane, stigmast-5-en-3-ol, cyclohexanol 2,6-dimethyl, and cyclohexasiloxane dodecamethyl on the surface of ALE-α-Fe2O3NPs. Cell viability assay and SEM imaging revealed significantly greater bacteriostatic and/or bactericidal effect of ALE-α-Fe2O3NPs in low EPS cells compared to pristine cells or bare-α-Fe2O3NPs. This is attributed to thinner protective layer of EPS around the low EPS cells, and higher dispersibility and stability of ALE-α-Fe2O3NPs. Absorption of ALE-α-Fe2O3NPs and bare-α-Fe2O3NPs on EPS surface and within EPS matrix was ascertained by atomic absorption spectroscopy (AAS). The results suggest differential internalization of ALE-α-Fe2O3NPs and bare-α-Fe2O3NPs in P. aeruginosa cells. The flow cytometry (FCM) results exhibited increased intracellular granularity in low EPS (18.94%) as compared with pristine (10.94%) cells, which signifies the greater internalization of ALE-α-Fe2O3NPs. Moreover, the proportionate increase in intracellular ROS generation in low EPS (20.47%) via-a-vis pristine (7.56%) cells was observed. Overall, the results elucidate that ALE-α-Fe2O3NPs-bacterial interaction leads to attachment of NPs to EPS surface, migration within the EPS matrix and penetration into cell, which eventually results in growth inhibition due to intracellular ROS activity. Owing to significant antibacterial and antibiofilm activities, ALE-α-Fe2O3NPs may serve as a good candidate for clinical management of extended spectrum beta lactamases (ESBL) positive P. aeruginosa.

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

There has been rapid increase globally in the production of functionally divergent nanoparticles in recent times. The uncontrolled discharge of such nanomaterials is a serious threat to the environment. We assess the impact of various-sized metal oxide nanoparticles (MONPs) on cell cycle progression and induction of oxidative stress in onions. Of these, CuO-NPs and TiO2-NPs significantly reduced the mitotic index (MI) by 28% and 17%, respectively, whereas Al2O3-NPs augmented the MI by 13% compared to untreated onion roots. The NPs internalization into the root tissues followed a dose dependent fashion. Also, several types of chromosomal aberration such as bridges, stickiness, vagrant, broken, and lag chromosomes were noticed. The reactive oxygen species activity of roots growing under CuO-NPs, Al2O3-NPs, and TiO2-NPs was significantly increased by 58, 30, and 10%, respectively. The superoxide dismutases activity (U g-1 FW) of roots increased from 2.4 ± 0.4 (control) to 6.1 ± 0.8 (CuO-NPs), 4.1 ± 0.2 (Al2O3-NPs) and 2.9 ± 0.2 (TiO2-NPs), whereas, catalase activity (mmoles min-1 g-1 FW) was recorded as 18.5 ± 2.1 (CuO-NPs), 15 ± 1.1 (Al2O3-NPs) and 13.8 ± 1 (TiO2-NPs) against 11.4 ± 1 (control). The formazan formed due to superoxide (O2˙-) reaction with nitroblue tetrazolium showed a dose dependent increase in roots treated with Al2O3-NPs and TiO2-NPs. Interestingly, under CuO-NPs exposure, the absorbance was considerably high at 200 µg ml-1 which dropped at 2000 µg ml-1 suggesting a clear attenuation of O2˙- by superoxide scavenging enzymes. The present findings provide base line data for better understanding of the mechanistic basis of phytotoxicity of MONPs to onion plants which can further be extended to other vegetable crops.