CuO nanoparticles significantly influence in vitro culture,steviol glycosides,and antioxidant activities of <Emphasis Type="Italic">Stevia rebaudiana</Emphasis> Bertoni

Copper oxide (CuO) nanoparticles (NPs) synthesized through co-precipitation method were employed in MS media during in vitro culture of Stevia rebaudiana. Physiological characteristics, production of steviol glycosides, and antioxidative parameters were investigated in regenerated plants. CuO NPs had crystalline monoclinic cubic cuprous oxides with average size 47 nm. The NPs were applied at 0, 0.1, 1.0, 10, 100 and 1000 mg/L in MS media for direct organogenesis of S. rebaudiana from nodal segments. Shoot organogenesis was found highest (88.5%) at 10 mg/L CuO and average shoot length, mean number of shoot per explant, and fresh weight were also found significantly higher at the same concentration. High performance liquid chromatography (HPLC) illustrated significant rise of bioactive major steviol glycosides (rebaudioside A and stevioside) at 10 mg/L CuO NPs in MS media. The oxidative stress produced by CuO nanoparticles on S. rebaudiana was affirmed by antioxidant activities i.e. total antioxidant activity (TAC), total reducing power (TRP) and 2,2-diphenyl-1-picryl hydrazyl (DPPH)-free radical scavenging activity. The oxidative stress generated by NPs involved production of antioxidative molecules total phenolic content (TPC), total flavonoid content (TFC) depending on NPs concentration. The study concludes that copper oxide nanoparticles functions as a stimulator of bioactive components productions, and can be employed in in vitro batch cultures.     

Long-term effects of CuO nanoparticles on the surface physicochemical properties of biofilms in a sequencing batch biofilm reactor

In this study, we examined the long-term effects of copper oxide nanoparticles (CuO NPs) on the production and properties of EPS and the resulting variations in surface physicochemical characteristics of biofilms in a sequencing batch biofilm reactor. After exposure to 50 mg/L CuO NPs for 45 days, the protein (PRO) and polysaccharide (PS) contents in loosely bound EPS (LB-EPS) decreased as the production of LB-EPS decreased from 34.4 to 30 mg TOC/g EPS. However, the production of tightly bound EPS (TB-EPS) increased by 16.47 % as the PRO and PS contents increased. The content of humic-like substances (HS) increased significantly, becoming the predominant constituent in EPS with the presence of 50 mg/L CuO NPs. Furthermore, the results of three-dimensional excitation-emission fluorescence spectra confirmed the various changes in terms of the LB-EPS and TB-EPS contents after exposure to CuO NPs. Fourier transform infrared spectroscopy showed that the –OH and –NH₂ groups of proteins in EPS were involved in the reaction with CuO NPs. Moreover, the chronic exposure to CuO NPs induced a negative impact on the flocculating efficiency of EPS and on the hydrophobicity and aggregation ability of microbial cells. The PRO/PS ratios of different EPS fractions were consistent with their hydrophobicities (R ² >0.98) and bioflocculating efficiencies (R ² >0.95); however, there was no correlation with aggregation ability. Additionally, the presence of bovine serum albumin (BSA) prevented the physical contact between CuO NPs and EPS as a result of NP aggregation and electrostatic repulsion.     

Comparative Study of Antibiofilm Activity of Copper Oxide and Iron Oxide Nanoparticles Against Multidrug Resistant Biofilm Forming Uropathogens

The effectiveness of the metal oxide nanoparticles viz. CuO and Fe₂O₃ as antibacterial agents against multidrug resistant biofilm forming bacteria was evaluated. CuO nanoparticles were also experimented for antibiofilm and time kill assay. The CuO displayed maximum antibacterial activity with zone of inhibition of (22 ± 1) mm against methicillin resistant Staphylococcus aureus (MRSA) followed by Escherichia coli (18 ± 1) mm. The Fe₂O₃ showed the zone of inhibition against MRSA of (14 ± 1) mm followed by E. coli (12 ± 1) mm. CuO proved to be more toxic than Fe₂O₃ nanoparticles showing significantly high antibacterial activity and found to possess dose dependent antibiofilm properties.     

Spectroscopic Studies on the Interaction of Fluorine Containing Triazole with Bovine Serum Albumin

The binding of one fluorine including triazole (C₁₀H₉FN₄S, FTZ) to bovine serum albumin (BSA) was studied by spectroscopic techniques including fluorescence spectroscopy, UV–Vis absorption, and circular dichroism (CD) spectroscopy under simulative physiological conditions. Fluorescence data revealed that the fluorescence quenching of BSA by FTZ was the result of forming a complex of BSA–FTZ, and the binding constants (K _a) at three different temperatures (298, 304, and 310 K) were 1.516?×?10⁴, 1.627?×?10⁴, and 1.711?×?10⁴?mol L^?1, respectively, according to the modified Stern–Volmer equation. The thermodynamic parameters ΔH and ΔS were estimated to be 7.752 kJ mol^?1 and 125.217 J?mol^?1?K^?1, respectively, indicating that hydrophobic interaction played a major role in stabilizing the BSA–FTZ complex. It was observed that site I was the main binding site for FTZ to BSA from the competitive experiments. The distance r between donor (BSA) and acceptor (FTZ) was calculated to be 7.42 nm based on the Förster theory of non-radioactive energy transfer. Furthermore, the analysis of fluorescence data and CD data revealed that the conformation of BSA changed upon the interaction with FTZ.     

Multi-spectroscopic and voltammetric evidences for binding,conformational changes of bovine serum albumin with thiamine

The interaction between thiamine hydrochloride (TA) and bovine serum albumin (BSA) was investigated by fluorescence, FTIR, UV–vis spectroscopic and cyclic voltammetric techniques under optimised physiological condition. The fluorescence intensity of BSA is gradually decreased upon addition of TA due to the formation of a BSA–TA complex. The binding parameters were evaluated and their behaviour at different temperatures was analysed. The quenching constants (K_sv) obtained were 2.6 × 10⁴, 2.2 × 10⁴ and 2.0 × 10⁴ L mol^?1 at 288, 298 and 308 K, respectively. The binding mechanism was static-type quenching. The values of ΔH° and ΔS° were found to be 26.87 kJ mol^?1 and 21.3 J K^?1 mol^?1, and indicated that electrostatic interaction was the principal intermolecular force. The changes in the secondary structure of BSA upon interaction with TA were confirmed by synchronous and 3-D spectral results. Site probe studies reveal that TA is located in site I of BSA. The effects of some common metal ions on binding of BSA–TA complex were also investigated.     

Molecular interactions of MnO2@RGO (manganese dioxide-reduced graphene oxide) nanocomposites with bovine serum albumin

Abstract

Graphene based materials have attracted global attention due to their excellent properties. GO-metal oxide nanocomposites have been conjugated with biomolecules for the development of novel materials and potentially used as biomarkers. Herein, a detailed study on the interaction of Bovine serum albumin (BSA) with MnO₂@RGO (manganese dioxide-reduced graphene oxide) nanocomposites (NC) has been carried out. MnO₂@RGO nanocomposites were prepared through a template/surfactant free hydrothermal route at 180?°C for 12?h by varying the graphene oxide (GO) concentration. Different biophysical experiments have been carried out to evaluate molecular interactions between BSA and NCs. Intrinsic fluorescence has been used to quantify the quenching efficiency of NCs and the binding association of BSA-NC complexes. NCs effectively quenched the intrinsic fluorescence of BSA via static and dynamic mechanism. Further, the results indicate that the molecular interactions of NC with BSA are dependent on the GO percentage in NC. Circular dichroism results demonstrate nominal changes in the secondary structure of BSA in presence of NCs. Also, the esterase-like activity of BSA was marginally affected after adsorption upon NCs. In addition, the FESEM micrographs reveal that the protein-NC complexes consist of nanorod and sheet-like morphologies are forming aggregates of different sizes. We hope that this study will provide a basis for the design of novel graphene based and other related nanomaterials for several biological applications.

Communicated by Ramaswamy H. Sarma     

Toxicity impacts of chemically and biologically synthesized CuO nanoparticles on cell suspension cultures of <Emphasis Type="Italic">Nicotiana tabacum</Emphasis>

Nanotechnology has quite a lot of applications in various fields of industrial sectors like food and agriculture. Although nanotechnology can improve the quality of life, its possible associated risks should be assessed. Here copper oxide nanoparticles (CuO NPs) were synthesized by chemical (polymer pyrolysis) and biological (green) methods with an average size of 30 and 44 nm, respectively. Afterwards, a cell biology approach was applied to evaluate the toxic effects of chemically and biologically synthesized CuO nanoparticles on tobacco cell suspension cultures. Both types of CuO nanoparticles significantly dropped the viability of the cells in a dose and time dependent manner. Accordingly, tobacco cells were found to increase the activity of antioxidant enzymes after 48 h of exposure to nanoparticles. The production of reactive oxygen species (ROS) and malondialdehyde (MDA) in a dose dependent manner was also observed. Assessment of the toxicity of CuO NPs revealed that chemically synthesized NPs were more toxic than biologically synthesized ones. It can be concluded that the organic components of the plant extract as capping agents that remain on the surface of green synthesized CuO NPs may reduce their toxicity effects.     

In vitro study on binding interaction of quinapril with bovine serum albumin (BSA) using multi-spectroscopic and molecular docking methods

The binding interaction between quinapril (QNPL) and bovine serum albumin (BSA) in vitro has been investigated using UV absorption spectroscopy, steady-state fluorescence spectroscopic, synchronous fluorescence spectroscopy, 3D fluorescence spectroscopy, Fourier transform infrared spectroscopy, circular dichroism, and molecular docking methods for obtaining the binding information of QNPL with BSA. The experimental results confirm that the quenching mechanism of the intrinsic fluorescence of BSA induced by QNPL is static quenching based on the decrease in the quenching constants of BSA in the presence of QNPL with the increase in temperature and the quenching rates of BSA larger than 10¹⁰ L mol^?1 s^?1, indicating forming QNPL–BSA complex through the intermolecular binding interaction. The binding constant for the QNPL–BSA complex is in the order of 10⁵ M^?1, indicating there is stronger binding interaction of QNPL with BSA. The analysis of thermodynamic parameters together with molecular docking study reveal that the main binding forces in the binding process of QNPL with BSA are van der Waal’s forces and hydrogen bonding interaction. And, the binding interaction of BSA with QNPL is an enthalpy-driven process. Based on Förster resonance energy transfer, the binding distance between QNPL and BSA is calculated to be 2.76 nm. The results of the competitive binding experiments and molecular docking confirm that QNPL binds to sub-domain IIA (site I) of BSA. It is confirmed there is a slight change in the conformation of BSA after binding QNPL, but BSA still retains its secondary structure α-helicity.     

Evaluation of DNA,BSA binding,and antimicrobial activity of new synthesized neodymium complex containing 29-dimethyl 110-phenanthroline

In order to evaluate biological potential of a novel synthesized complex [Nd(dmp)₂Cl₃.OH₂] where dmp is 29-dimethyl 110-phenanthroline, the DNA-binding, cleavage, BSA binding, and antimicrobial activity properties of the complex are investigated by multispectroscopic techniques study in physiological buffer (pH 7.2).The intrinsic binding constant (K_b) for interaction of Nd(III) complex and FS–DNA is calculated by UV–Vis (K_b = 2.7 ± 0.07 × 10⁵) and fluorescence spectroscopy (K_b = 1.13 ± 0.03 × 10⁵). The Stern–Volmer constant (K_SV), thermodynamic parameters including free energy change (ΔG°), enthalpy change (?H°), and entropy change (?S°), are calculated by fluorescent data and Vant’ Hoff equation. The experimental results show that the complex can bind to FS–DNA and the major binding mode is groove binding. Meanwhile, the interaction of Nd(III) complex with protein, bovine serum albumin (BSA), has also been studied by using absorption and emission spectroscopic tools. The experimental results show that the complex exhibits good binding propensity to BSA. The positive ΔH° and ?S° values indicate that the hydrophobic interaction is main force in the binding of the Nd(III) complex to BSA, and the complex can quench the intrinsic fluorescence of BSA remarkably through a static quenching process. Also, DNA cleavage was investigated by agarose gel electrophoresis that according to the results cleavage of DNA increased with increasing of concentration of the complex. Antimicrobial screening test gives good results in the presence of Nd(III) complex system.     

Detection of interaction between lysionotin and bovine serum albumin using spectroscopic techniques combined with molecular modeling

A combination of fluorescence, UV–Vis absorption, circular dichroism (CD), Fourier transform infrared (FT-IR) and molecular modeling approaches were employed to determine the interaction between lysionotin and bovine serum albumin (BSA) at physiological pH. The fluorescence titration suggested that the fluorescence quenching of BSA by lysionotin was a static procedure. The binding constant at 298 K was in the order of 10⁵ L mol^?1, indicating that a high affinity existed between lysionotin and BSA. The thermodynamic parameters obtained at different temperatures (292, 298, 304 and 310 K) showed that the binding process was primarily driven by hydrogen bond and van der Waals forces, as the values of the enthalpy change (ΔH°) and entropy change (ΔS°) were found to be ?40.81 ± 0.08 kJ mol^?1 and ?35.93 ± 0.27 J mol^?1 K^?1, respectively. The surface hydrophobicity of BSA increased upon interaction with lysionotin. The site markers competitive experiments revealed that the binding site of lysionotin was in the sub-domain IIA (site I) of BSA. Furthermore, the molecular docking results corroborated the binding site and clarified the specific binding mode. The results of UV–Vis absorption, CD and FT-IR spectra demonstrated that the secondary structure of BSA was altered in the presence of lysionotin.     

Preparation,characterization and cytotoxic evaluation of bovine serum albumin nanoparticles encapsulating 5-methylmellein: A secondary metabolite isolated from Xylaria psidii

In this study, 5-methylmellein (5-MM) loaded bovine serum albumin nanoparticles (BSA NPs) were developed using desolvation technique. The developed nanoparticles were characterized for their mean particle size, polydispersity, zeta potential, loading efficiency, X-ray diffractometry (XRD), differential scanning calorimetry (DSC) and release profile. The developed nanoparticles were spherical in shape under transmission electron microscopy (TEM) and atomic force microscopy (AFM). The developed 5-MM loaded BSA NPs demonstrated a mean particle size with a diameter of 154.95?±?4.44?nm. The results from XRD and DSC studies demonstrated that the crystal state of the 5-MM was converted to an amorphous state in polymeric matrix. The encapsulation and loading efficiency was found to be 73.26?±?4.48% and 7.09?±?0.43%. The in vitro cytotoxicity in human prostate cancer cell line (PC-3), human colon cancer cells (HCT-116) and human breast adenocarcinoma cell line (MCF-7) cells demonstrated enhanced cytotoxicity of 5-MM BSA NPs as compared to native 5-MM after 72-h treatment. The enhancement in cytotoxicity of 5-MM BSA NPs was also supported by increase in cellular apoptosis, mitochondrial membrane potential loss and generation of high reactive oxygen species (ROS). In conclusion, these findings collectively indicated that BSA nanoparticles may serve as promising drug delivery system for improving the efficacy of 5-methylmellein.     

Toxic effects of nanoparticles on bioluminescence activity,seed germination,and gene mutation

The potential environmental toxicities of several metal oxide nanoparticles (NPs; CuO, TiO₂, NiO, Fe₂O₃, ZnO, and Co₃O₄) were evaluated in the context of bioluminescence activity, seed germination, and bacterial gene mutation. The bioassays exhibited different sensitivities, i.e., each kind of NP exhibited a different level of toxicity in each of the bioassays. However, with a few exceptions, CuO and ZnO NPs had most toxic for germination of Lactuca seed (EC₅₀ 0.46 mg CuO/l) and bioluminescence (EC₅₀ 1.05 mg ZnO/l). Three NPs (Co₃O₄, TiO₂, and Fe₂O₃) among all tested concentrations (max. 1,000 mg/l) showed no inhibitory effects on the tested organisms, except for Co₃O₄ NPs on bioluminescence activity (EC₅₀ 62.04 mg/l). The sensitivity of Lactuca seeds was greater than that of Raphanus seeds (EC₅₀ 0.46 mg CuO/l versus 26.84 mg CuO /l ). The ranking of metal toxicity levels on bioluminescence was in the order of ZnO?>?CuO?>?Co₃O₄?>?NiO?>?Fe₂O₃, TiO₂, while CuO?>?ZnO?>?NiO?>?Co₃O₄, Fe₂O₃, TiO₂ on germination. No revertant mutagenic ratio (greater than 2.0) of Salmonella typhimurium TA 98 was observed under any tested condition. These findings demonstrate that several bioassays, as opposed to any single one, are needed for the accurate assessment of NP toxicity on ecosystems.     

Binding of anti-cardiovascular drug to serum albumin: an insight in the light of spectroscopic and computational approaches

Isoprenaline hydrochloride is a potential cardiovascular drug helps in the smooth functioning of the heart muscles. So, we have performed the binding study of ISO with BSA. This study was investigated by UV absorption, fluorescence, synchronous fluorescence, circular dichroism, etc. The analysis of intrinsic fluorescence data showed the low binding affinity of ISO. The binding constant K_b was 2.8 × 103 M-1 and binding stoichiometry (n) was approximately one and the Gibb’s free energy change at 310 K was determined to be -8.69 kcal mol^?1. Negative Gibb’s free energy change shows the spontaneity of the BSA and ISO interaction. We have found ISO-induced alternation in the UV absorption, synchronous fluorescence and CD spectra in the absence and presence of the quencher indicates the complex formation. In synchronous fluorescence, red shift was obtained because of the complex formation of BSA and ISO. The distance (r) between the BSA (donor) and ISO (acceptor) was 2.89 nm, determined by FRET. DLS measurements interpreted complex formation due to the reduction in hydrodynamic radii of the protein in the presence of the drug. The binding site of ISO was found to be nearer to Trp 134 with the help of molecular docking and the ΔG° was found to be –10.2 kcal mol^?1. The esterase activity result suggests that ISO acts as competitive inhibitor. Thus, this study would help to determine the binding capacity of the drug to the protein which may indicate the efficiency of diffusion of ISO into the blood for the treatment of heart diseases.     

Spectroscopic Investigation of the Interaction Between Copper (II) 2-oxo-propionic Acid Salicyloyl Hydrazone Complex and Bovine Serum Albumin

The interaction between copper (II) 2-oxo-propionic acid salicyloyl hydrazone (Cu^IIL) and bovine serum albumin (BSA) under physiological conditions was investigated by the methods of fluorescence spectroscopy, UV-Vis absorption, and circular dichroism spectroscopy. Fluorescence data showed that the fluorescence quenching of BSA by Cu^IIL was the result of the formation of the BSA–Cu^IIL complex. The apparent binding constants (K _a) between Cu^IIL and BSA at four different temperatures were obtained according to the modified Stern–Volmer equation. The thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS), for the reaction were calculated to be ?80.79 kJ mol^?1 and ?175.48 J mol^?1 K^?1 according to van’t Hoff equation. The results indicated that van der Waals force and hydrogen bonds were the dominant intermolecular force in stabilizing the complex. The binding distance (r) between Cu^IIL and the tryptophan residue of BSA was obtained to be 4.1 nm according to Förster’s nonradioactive energy transfer theory. The conformational investigation showed that the application of Cu^IIL increased the hydrophobicity of amino acid residues and decreased the α-helical content of BSA (from 62.71% to 37.31%), which confirmed some microenvironmental and conformational changes of BSA molecules.     

Isolation of copper oxide (CuO) nanoparticles resistant Pseudomonas strains from soil and investigation on possible mechanism for resistance

The present study deals with isolation and characterization of copper oxide nanoparticles resistant Pseudomonas strains that were isolated from the soil collected from mining and refining sites of Sarcheshmeh copper mine in the Kerman Province of Iran. The three isolates were selected based on high level of copper oxide nanoparticles (CuO NPs) resistance. The isolates were authentically identified as Pseudomonas fluorescens CuO-1, Pseudomonas fluorescens CuO-2 and Pseudomonas sp. CuO-3 by morphological, biochemical and 16S rDNA gene sequencing analysis. The growth pattern of these isolates with all the studied CuO NPs concentrations was similar to that of control (without CuO NPs) indicating that CuO NPs would not affect the growth of isolated strains. A reduction in the amount of exopolysaccharides was observed after CuO NPs—P. fluorescens CuO-1 culture supernatant interaction. The Fourier transform infrared spectroscopy (FT-IR) peaks for the exopolysaccharides extracted from the bacterial culture supernatant and the interacted CuO NPs were almost similar. The exopolysaccharide capping of the CuO NPs was confirmed by FT-IR and X-ray diffraction analysis. The study of bacterial exopolysaccharides capped CuO NPs with E. coli PTCC 1338 and S. aureus PTCC 1113 showed less toxicity compared to uncoated CuO NPs. Our study suggests that the capping of nanoparticles by bacterially produced exopolysaccharides serve as the probable mechanism of tolerance.     

Ecotoxicological impacts of exposure to copper oxide nanoparticles on the gill of the Swan mussel,Anodonta cygnea (Linnaeus, 1758)

This study was conducted to investigate the ecotoxicological effects of exposure to copper oxide nanoparticles (CuO NPs) on the gill of the swan mussel Anodonta cygnea using several approaches including qualitative and quantitative histopathology, ultra-morphology (scanning electron microscopy [SEM]) and measures of clearance rate (CR) and bioaccumulation of CuO NPs. Histological alterations in mussels exposed to 0.25 (T1), 2.5 (T2) and 25.0?µg L^?1 (T3) CuO NPs for 12 days include changes in the length and form of gill lamellae, changes in inter-lamellar spaces, epithelial hyperplasia, atrophy and tissue rupture. Ultra-morphological changes following CuO NP exposure included epithelial hyperplasia and hypertrophy, epithelial lifting, tissue rupture (water channel fusion) and extensive necrosis of the gill surfaces. I_Gill (gill damage severity) index values for both histopathological and ultra-morphological data were significantly (P?0.05) higher in T3. The CR of mussels was significantly (P??1 g^?1 dry weight]) in comparison to controls (CR?=?108?±?47.14 [L min^?1 g^?1 dry weight]). CuO NPs accumulated in exposed mussels at all exposure concentrations until day 4, but there was no further change in accumulation levels by the end of the exposure period. The accumulated content of CuO NPs was significantly (P??1 exposure concentration. Based on these results, significant accumulation of CuO NPs in the gills of swan mussel could affect histological and ultra-structural characteristics of this organ and consequently have deleterious impacts on its filtration activity.     

Topical Formulation Containing Beeswax-Based Nanoparticles Improved <Emphasis Type="Italic">In Vivo</Emphasis> Skin Barrier Function

Lipid nanoparticles have shown many advantages for treatment/prevention of skin disorders with damaged skin barrier function. Beeswax is a favorable candidate for the development of nanosystems in the cosmetic and dermatological fields because of its advantages for the development of products for topical application. In the present study, beeswax-based nanoparticles (BNs) were prepared using the hot melt microemulsion technique and incorporated to a gel-cream formulation. The formulation was subsequently evaluated for its rheological stability and effect on stratum corneum water content (SCWC) and transepidermal water loss (TEWL) using in vivo biophysical techniques. BNs resulted in mean particle size of 95.72?±?9.63 nm and zeta potential of ?9.85?±?0.57 mV. BN-loaded formulation showed shear thinning behavior, well adjusted by the Herschel-Bulkley model, and a small thixotropy index that were stable for 28 days at different temperatures. BN-loaded formulation was also able to simultaneously decrease the TEWL and increase the SCWC values 28 days after treatment. In conclusion, the novel beeswax-based nanoparticles showed potential for barrier recovery and open the perspective for its commercial use as a novel natural active as yet unexplored in the field of dermatology and cosmetics for treatment of skin diseases with damaged skin barrier function.     

The influence of redox conditions in soils on extraplasmatic Fe-loading of plant roots

Loading of extraplasmatic Fe, as a potential storage pool for Fe nutrition, was studied in roots of maize grown under hypoxic conditions in soil culture. Extraplasmatic Fe loading was investigated depending on (i) duration of flooding (0, 1, 2 or 4 days) and (ii) microbial activity as affected by graduated addition of carbon sources (0, 2 or 10 g each starch and cellulose kg^?1 soil). Maize plants were grown in a soil culture system with root systems enclosed in membrane bags to avoid Fe contamination of the root surface by soil particles. Due to the high redox buffer capacity of the Haplic Luvisol employed for the experiments, flooding treatments induced only moderately reducing conditions (～?300 mV) and a slight increase of extraplasmatic Fe loading (41\to165 mg kg^?1 d.m.). Strongly reducing conditions (?100 mV) associated with a high Fe²⁺ concentration in the soil solution and a significant increase of extraplasmatic Fe (1190 mg kg^?1 d.m.) were obtained only after application of high amounts of organic carbon (10 g starch and 10 g cellulose kg^?1 soil), which accompanied by unrealistic reducing conditions due to intense stimulation of microbial growth. The expression of effects only under extremely high application level of organic carbon (～?33 t C ha^?1) suggest that similar to aerobic conditions, extraplasmatic Fe-loading under transient hypoxia is probably of limited ecological significance for the iron nutrition of higher plants, at least in soils with a high redox buffer capacity as employed in the present study. Abbreviations: DHA – dehydrogenase activity; d.m. – dry matter; DOC – dissolved organic carbon; Eh – redox potential; PIXE – proton-induced X-ray emission; STIM – scanning transmission ion microscopy.     

Effect of Zinc Oxide Nanoparticles on the Function of MC3T3-E1 Osteoblastic Cells

Zinc oxide nanoparticles (ZnO NPs) can be ingested directly when used in food, food packaging, drug delivery, and cosmetics. This study evaluated the cellular effects of ZnO NPs (50 and 100 nm diameter particle sizes) on the function of osteoblastic MC3T3-E1 cells. ZnO NPs showed cytotoxicity at concentrations of above 50 μg/ml, and there was no significant effect of the size on the cytotoxicity of ZnO NPs. Within the testing concentrations of 0.01～1 μg/ml, which did not cause a marked drop in cell viability, ZnO NPs (0.1 μg/ml) caused a significant elevation of alkaline phosphatase activity, collagen synthesis, mineralization, and osteocalcin content in the cells (P?<?0.05). Moreover, pretreatment with ZnO NPs (0.01～1 μg/ml) significantly reduced antimycin A-induced cell damage by preventing mitochondrial membrane potential dissipation, complex IV inactivation, and ATP loss. Measurement of reactive oxygen species (ROS) indicated decrease in ROS level upon exposure to ZnO nanoparticles (0.01 μg/ml). Hence, our study indicated that ZnO nanoparticles can have protective effects on osteoblasts at low concentrations where there are little or no observable cytotoxic effects.     

Studies on the interaction between nanodiamond and human hemoglobin by surface tension measurement and spectroscopy methods

In this study, a novel method to probe molecular interactions and binding of human hemoglobin (Hb) with nanodiamond (ND) was introduced based on the surface tension measurement. This method complements conventional techniques, which are basically done by zeta potential and dynamic light scattering (DLS) measurements, near and far circular dichroism (CD) spectroscopy, intrinsic and extrinsic fluorescence spectroscopy. Addition of ND to Hb solution increased the surface tension value of Hb–ND complex relative to those of Hb and ND molecules. The zeta potential values reveled that Hb and ND provide identical charge distribution at pH 7.5. DLS measurements demonstrated that Hb, ND, and ND–Hb complex have hydrodynamic radiuses of 98.37 ± 4.57, 122.07 ± 7.88 nm and 62.27 ± 3.70 at pH of 7.5 respectively. Far and near UV-CD results indicated the loss of α-helix structure and conformational changes of Hb, respectively. Intrinsic fluorescence data demonstrated that the fluorescence quenching of Hb by ND was the result of the static quenching. The hydrophobic interaction plays a pivotal role in the interaction of ND with Hb. Fluorescence intensity changes over time revealed conformational change of Hb continues after the mixing of the components (Hb–ND) till 15 min, which is indicative of the denaturation of the Hb relative to the protein control. Extrinsic fluorescence data showed a considerable enhancement of the ANS fluorescence intensity of Hb–ND system relative to the Hb till 60 nM of ND, likely persuaded by greater exposure of nonpolar residues of Hb hydrophobic pocket. The remarkable decrease in T_m value of Hb in Hb–ND complex exhibits interaction of Hb with ND conducts to conformational changes of Hb. This study offers consequential discrimination into the interaction of ND with proteins, which may be of significance for further appeal of these nanoparticles in biotechnology prosecution.