Vibrational two-photon microscopy for tissue imaging: Short-wave infrared surface-enhanced resonance hyper-Raman scattering

Multiphoton microscopy using short-wave infrared (SWIR) radiation offers nondestructive and high-resolution imaging through tissue. Two-photon fluorescence (TPF), for example, is commonly employed to increase the penetration depth and spatial resolution of SWIR imaging, but the broad spectral peaks limit its multiplexing capabilities. Hyper-Raman scattering, the vibrational analog of TPF, yields spectral features on the order of 20 cm^?1 and reporter-functionalized noble metal nanoparticles (NPs) provide a platform for both hyper-Raman signal enhancement and selective targeting in biological media. Herein we report the first tissue imaging study employing surface-enhanced resonance hyper-Raman scattering (SERHRS), the two-photon analog of surface-enhanced resonance Raman scattering. Specifically, we employ multicore gold-silica NPs (Au@SiO₂ NPs) functionalized with a near infrared-resonant cyanine dye, 3,3′-diethylthiatricarbocyanine iodide as a SERHRS reporter. SWIR SERHRS spectra are efficiently acquired from mouse spleen tissue. SWIR SERHRS combines two-photon imaging advantages with narrow vibrational peak widths, presenting future applications of multitargeted bioimaging.     

Analytical Modeling Based on Modified Effective Medium Theories for Optical Properties of Photovoltaic Material-Incorporated Plasmonic Nanoparticles

Theoretical guidance on the optical properties of plasmonic nanoparticles (NPs) is of significant importance in tremendous numbers of fields like photovoltaics. The incorporation of plasmonic NPs into photovoltaic material can promote optical absorption either via the excitation of localized surface plasmon resonance (LSPR) modes or due to multiple light scattering. Since most fabrication techniques for the incorporation of NPs into photovoltaic material result in a random array of NPs with various sizes, numerical simulations based on solving the Maxwell equations are computationally expensive and prohibitively slow for this large number of NPs. Therefore, in this paper, based on modified effective medium theories, taking into account finite size of NPs, size dispersion for NPs, extrinsic dynamic effect, and intrinsic confinement effect, fast and cost-effective analytical modeling, considering both LSPR and scattering effects, is presented to obtain the optical properties of photovoltaic material incorporated by spherical NPs with nonuniform size and random distribution. Then, by means of presented analytical modeling, considering reasonably low and high volume fractions of NPs in addition to small and large size of NPs, the effect of different parameters of embedded NPs into organic and inorganic photovoltaic materials is explored.

     

Interaction of glucose‐derived carbon quantum dots with silver and gold nanoparticles and its application for the fluorescence detection of 6‐thioguanine

The interaction of glucose‐derived carbon quantum dots (CQDs) with silver (Ag) and gold (Au) nanoparticles (NPs) was explored by fluorescence spectroscopy. Both metal NPs cause an efficient quenching of CQD fluorescence, which is likely due to the energy transfer process between CQDs as donors and metal NPs as acceptors. The Stern–Volmer plots were evaluated and corresponding quenching constants were found to be 1.9 × 10¹⁰ and 2.2 × 10⁸ M^?1 for AgNPs and AuNPs, respectively. The analytical applicability of these systems was demonstrated for turn‐on fluorescence detection of the anti‐cancer drug, 6‐thioguanine. Because the CQD–AgNP system had much higher sensitivity than the CQD–AuNP system, we used it as a selective fluorescence probe in a turn‐on assay of 6‐thioguanine. Under optimum conditions, the calibration graph was linear from 0.03 to 1.0 μM with a detection limit of 0.01 μM. The developed method was applied to the analysis of human plasma samples with satisfactory results.     

Metal–Organic Framework Templated Porous Carbon‐Metal Oxide/Reduced Graphene Oxide as Superior Support of Bimetallic Nanoparticles for Efficient Hydrogen Generation from Formic Acid

Ultrafine PdAg nanoparticles (NPs) are successfully immobilized on zirconia/porous carbon/reduced graphene oxide (ZrO₂/C/rGO) nanocomposite derived from metal organic framework/graphene oxide. Monodispersed PdAg NPs (diameter ≤2.5 nm) can be facilely anchored on the ZrO₂/C/rGO and the aggregation of metal NPs can be avoided utmostly. By virtue of the synergistic effect between metal NPs and support, the resulting PdAg@ZrO₂/C/rGO exhibits excellent activity (turnover frequency, 4500 h^?1 at 333 K) for the dehydrogenation of formic acid. As an effective strategy, it provides an opportunity to immobilize ultrafine metal NPs on metal oxide/porous carbon/reduced graphene oxide, which has tremendous application prospects in various catalytic fields.     

Biosynthesis of au nanoparticles by a marine bacterium and enhancing their catalytic activity through metal ions and metal oxides

The authors report that a marine Shewanella sp. CNZ-1 is capable of producing Au NPs under various conditions. Results showed that initial concentration of Au(III), pH values and electron donors affected nucleation of Au NPs by CNZ-1, resulting in different apparent color of the as-obtained bio-Au NPs, which were further characterized by UV-Vis, TEM, XRD, and XPS analyses. Mechanism studies revealed that Au(III) was first reduced to Au(I) and eventually reduced to EPS-coated Au⁰ NPs. FTIR and FEEM analyses revealed that some amides and humic acid-like matters were involved in the production of bio-Au NPs through CNZ-1 cells. In addition, the authors also found that the catalytic activity of bio-Au NPs for 4-nitrophenol (4-NP) reduction could be enhanced by various metal ions (Ca²⁺, Cu²⁺, Co²⁺, Fe²⁺, Fe³⁺, Ni²⁺, Sr²⁺, and Cr³⁺) and metal oxides (Fe₃O₄, Al₂O₃, and SiO₂), which is beneficial for their further practical application. The maximum zero-order rate constant k ₁ and first-order rate constant k₂ of all metal ions/oxides supplemented systems can reach 99.65 mg/(L^.min) and 2.419 min⁻¹, which are 11.3- and 12.6-fold higher than that of control systems, respectively. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2727, 2019.     

Fluorescence enhancement monitoring of pyrromethene laser dyes by metallic Ag nanoparticles

Fluorescence enhancement monitoring of pyrromethene laser dyes using their complexation with Ag nanoparticles (Ag NPs) was studied. The size of the prepared Ag NPs was determined by transmission electron spectroscopy and UV/Vis absorption spectroscopy. Mie theory was also used to confirm the size of NPs theoretically. The effect of different nanoparticle concentrations on the optical properties of 1 × 10^‐4 M PM dyes shows that 40%of Ag NPs concentration (40%C Ag NPs) in complex is the optimum concentration. Also, the effects of different concentrations of PM dyes in a complex was measured. Emission enhancement factors were calculated for all samples. Fluorescence enhancement efficiencies depended on the input pumping energy of a Nd‐YAG laser (wavelength 532 nm and 8 ns pulse duration) were reported and showed the lowest energy (28 and 32 mJ) in the case of PM567 and PM597, respectively. Copyright © 2014 John Wiley & Sons, Ltd.     

Recent advances in nanomaterials-based optical sensors for detection of various biomarkers (inorganic species,organic and biomolecules)

This review briefly emphasizes the different detection approaches (electrochemical sensors, chemiluminescence, surface-enhanced Raman scattering), functional nanostructure materials (quantum dots, metal nanoparticles, metal nanoclusters, magnetic nanomaterials, metal oxide nanoparticles, polymer-based nanomaterials, and carbonaceous nanomaterials) and detection mechanisms. Furthermore, the emphasis of this review is on the integration of functional nanomaterials with optical spectroscopic techniques for the identification of various biomarkers (nucleic acids, glucose, uric acid, oxytocin, dopamine, ascorbic acid, bilirubin, spermine, serotonin, thiocyanate, Pb²⁺, Cu²⁺, Hg²⁺, F⁻, peptides), and cancer biomarkers (mucin 1, prostate specific antigen, carcinoembryonic antigen, CA15-3, human epidermal growth factor receptor 2, C-reactive protein, and interleukin-6). Analytical characteristics of nanomaterials-based optical sensors are summarized in the tables, providing the insights of nanomaterials-based optical sensors for biomarkers detection. Finally, the opportunities and challenges of nanomaterials-based optical analytical approaches for the detection of various biomarkers (inorganic, organic, biomolecules, peptides and proteins) are discussed.     

Effect of TiO2 NPs on the growth,anatomic features and biochemistry parameters of Baby sun rose (Aptenia cordifolia)

Rapid commercialization, industrialization and the use of nanotechnology has led to an increase in the distribution of nanoparticles (NPs) in the environment. The most common metal oxide NPs which is present within products is Titanium dioxide (TiO₂). TiO₂ NPs have photocatalytic nature and can affect plant growth. The current study investigated the morphological, anatomical and biochemical features of Baby sun rose (Aptenia cordifolia) after exposure to different concentrations of TiO₂ nanoparticles (0, 1, 5, 10 and 20 mg L⁻¹). Treatment with TiO₂ NPs showed changes in the morphological features and increased photosynthetic pigmentation within the plant. An increase in the level of phenolics (12%) and flavonoid compounds (13%) was observed when plants were treated with moderate levels of TiO₂ NPs. A reduction in the diameter of the vascular bundles and increased thickening of the transverse wall were observed in several samples. The number of scattered vascular bundles in the stems increased. The morphological, biochemical, and anatomical responses of Baby sun rose indicates that plants can adapt to environments contaminated with up to 20 mg L⁻¹ TiO₂ NPs_. The cultivation of Baby sun rose plants in environments polluted with TiO₂ NPs is recommended. This study enhances the knowledge of the effect of TiO₂ NPs on the growth of Baby sun rose which is an ornamental plant, widely cultivated in different regions of Iran. The results of this study suggest that contaminated environments up to 20 mg L⁻¹ TiO₂ NPs can be managed by phytoremediation. Further studies are needed to investigate this plant''s tolerance strategies against stress caused by TiO₂ NPs and bulk TiO₂ as well as the effect of other nanoparticles on plant.     

Chiral Recognition of Tyrosine Enantiomers Based on Decreased Resonance Scattering Signals With Silver Nanoparticles as Optical Sensor

A novel chiral sensing platform, employing silver nanoparticles capped with N‐acetyl‐L‐cysteine (NALC‐Ag NPs), was utilized for the discrimination of L‐tyrosine and D‐tyrosine. This nanosensor, which could be used as an optical sensing unit and chiral probe, was characterized by transmission electron microscopy (TEM) and resonance Rayleigh scattering (RRS) spectroscopy. After the proposed sensing platform interacted with L‐tyrosine and D‐tyrosine, a decreased resonance scattering signal was only obtained from L‐tyrosine. This phenomenon offered a useful assay for the selectivity and determination of L‐tyrosine with the RRS method. The linear range and detection limit of L‐tyrosine were 0.2838–20.0 µg⋅mL^‐1 and 0.0860 µg⋅mL^‐1, respectively. In addition, experimental factors such as acidity, interaction time, and the concentration of enantiomers were investigated with regard to the effect on enantioselective interaction. Chirality 27:194–198, 2015. © 2014 Wiley Periodicals, Inc.     

Silver Nanoparticles and Nanorings for Surface-Enhanced Raman Scattering

Silver (Ag) nanoparticles (NPs) and Ag nanorings (NRs) have been fabricated. Due to the inherent features of Ag NPs and Ag NRs, strong electromagnetic (EM) near-field distributions were expected, and hence surface-enhanced Raman scattering (SERS) activity was demonstrated. Size and interparticle gaps distribution of Ag NPs were estimated to be 48.14?±?10.14 nm and 14.11?±?5.24 nm respectively along with estimated coverage density of?~?4?×?10¹⁰ cm^?2. On the other hand, Ag NRs were found to consist of Ag clusters and of various shapes and sizes, instead of a perfect ring structure. High-resolution FESEM revealed that the individual constituent clusters were different from each other, particularly in terms of size and shape in addition to the cases how such clusters were connected to form the edge of the NR. However, the coverage density of Ag NRs was estimated to be?~?5.6?×?10⁶ cm^?2. Based on the scenarios, it was speculated that the local EM near-field distribution would excel and thus led to enhanced SERS signals. SERS enhancement of R6G was estimated as high as 2.18?×?10⁴ and 2.78?×?10⁴ at 610 cm^?1 (C???C ring bending mode in phenyl rings) for Ag NPs and Ag NRs respectively. FDTD analysis was carried out to elucidate the EM near-field distributions.

Graphical abstract

Ag NPs and Ag NRs from an ultrathin layer of Ag on ZnO/Glass (middle pane) confirming high EF of R6G adsorbed on Ag NRs (right pane) and Ag NPs (left pane) supported by corresponding EM near-field distributions.

     

Nonlinear Dependences of Optical Properties of Spherical Core–Shell Silver–Gold and Gold–Silver Nanoparticles on Their Parameters

Modeling of nonlinear optical properties of spherical core–shell gold–silver and silver–gold nanoparticles (NPs) placed in water was carried out on the base of extended Mie theory. Efficiency cross sections of absorption σ _abs, scattering σ _sca, and extinction σ _ext of radiation with wavelengths λ?=?400 and 532 nm for core–shell NPs with constant core radii r ₀₀?=?5, 10, 20, and 40 nm and in the range of relative radii r ₁/r ₀₀?=?1–8 were calculated (r ₁ is the radius of shell). Dependences of optical properties of gold–silver and silver–gold NPs on increasing of core radius r ₀ in the range 0???r ₁ under condition r ₁?=?const and increasing of r ₀ under r ₁???r ₀?=?const were investigated. Results show the nonlinear behavior of optical properties of core–shell gold–silver and silver–gold NPs on radiation wavelengths (optical indexes of metals), different core and shell radii, and their correlation, on relative NP radii r ₁/r ₀₀. An increase and decrease of absorption, scattering, and extinction efficiency cross sections of core–shell NPs with changing of wavelengths, core and shell radii, and relative NP radii r ₁/r ₀₀ are established. These dependences can be used for experimental investigation of the interesting first stages of shell formation on core and optical determination of core–shell NP parameters.     

Use of ZnO:Tb down‐conversion phosphor for Ag nanoparticle plasmon absorption using a He–Cd ultraviolet laser

Although noble metal nanoparticles (NPs) have attracted some attention for potentially enhancing the luminescence of rare earth ions for phosphor lighting applications, the absorption of energy by NPs can also be beneficial in biological and polymer applications where local heating is desired, e.g. photothermal applications. Strong interaction between incident laser light and NPs occurs only when the laser wavelength matches the NP plasmon resonance. Although lasers with different wavelengths are available and the NP plasmon resonance can be tuned by changing its size and shape or the dielectric medium (host material), in this work, we consider exciting the plasmon resonance of Ag NPs indirectly with a He–Cd UV laser using the down‐conversion properties of Tb³⁺ ions in ZnO. The formation of Ag NPs was confirmed by X‐ray diffraction, transmission electron microscopy and UV–vis diffuse reflectance measurements. Radiative energy transfer from the Tb³⁺ ions to the Ag NPs resulted in quenching of the green luminescence of ZnO:Tb and was studied by means of spectral overlap and lifetime measurements. The use of a down‐converting phosphor, possibly with other rare earth ions, to indirectly couple a laser to the plasmon resonance wavelength of metal NPs is therefore successfully demonstrated and adds to the flexibility of such systems. Copyright © 2016 John Wiley & Sons, Ltd.     

Biodistribution of 125I-labeled polymeric vaccine carriers after subcutaneous injection

Polymeric nanoparticles (NPs) comprised of hydrophilic poly(γ-glutamic acid) in the main chain and hydrophobic phenylalanine in the side chain (γ-PGA-Phe) are a promising vaccine carrier for various kinds of diseases. However, little is known about the fate of subcutaneously administered γ-PGA-Phe NPs. Therefore, we newly synthesized γ-PGA graft phenylalanine and tyrosine conjugates (γ-PGA-Phe-Tyr), and then γ-PGA-Phe-Tyr NPs were labeled with ¹²⁵I for monitoring their biodistribution (γ-PGA-Phe-Tyr(¹²⁵I) NPs). Dynamic light scattering (DLS) measurements showed that γ-PGA-Phe-Tyr(¹²⁵I) NPs showed 200 nm in diameter and a negative ζ-potential, which was comparable to those of their precursors. γ-scintigraphic images showed that in mice, subcutaneously injected γ-PGA-Phe-Tyr(¹²⁵I) NPs were mainly observed at the site of injection (SOI), but not other organs 1 h after administration. However, γ-PGA-PheTyr(¹²⁵I) NPs were almost undetectable at the SOI and other organs at 11 days postinjection. Similar results were observed when γ-PGA-Phe-Tyr(¹²⁵I) NPs were subcutaneously injected into rats. Furthermore, at 11 days postinjection, 73 ± 3% of the injected dose of γ-PGA-Phe-Tyr(¹²⁵I) NPs was detected in the feces (14 ± 1%) and urine (59 ± 1%). These results clearly showed that subcutaneously injected γ-PGA-Phe-Tyr(¹²⁵I) NPs were cleared from the body, and γ-PGA-Phe NPs were safe and effective vaccine carriers.     

The influence of H2 partial pressure on biogenic palladium nanoparticle production assessed by single-cell ICP-mass spectrometry

The production of biogenic palladium nanoparticles (bio-Pd NPs) is widely studied due to their high catalytic activity, which depends on the size of nanoparticles (NPs). Smaller NPs (here defined as <100 nm) are more efficient due to their higher surface/volume ratio. In this work, inductively coupled plasma-mass spectrometry (ICP-MS), flow cytometry (FCM) and transmission electron microscopy (TEM) were combined to obtain insight into the formation of these bio-Pd NPs. The precipitation of bio-Pd NPs was evaluated on a cell-per-cell basis using single-cell ICP-MS (SC-ICP-MS) combined with TEM images to assess how homogenously the particles were distributed over the cells. The results provided by SC-ICP-MS were consistent with those provided by “bulk” ICP-MS analysis and FCM. It was observed that heterogeneity in the distribution of palladium over an entire cell population is strongly dependent on the Pd²⁺ concentration, biomass and partial H₂ pressure. The latter three parameters affected the particle size, ranging from 15.6 to 560 nm, and exerted a significant impact on the production of the bio-Pd NPs. The TEM combined with SC-ICP-MS revealed that the mass distribution for bacteria with high Pd content (144 fg Pd cell⁻¹) indicated the presence of a large number of very small NPs (D50 = 15.6 nm). These results were obtained at high cell density (1 × 10⁵ ± 3 × 10⁴ cells μl⁻¹) and H₂ partial pressure (180 ml H₂). In contrast, very large particles (D50 = 560 nm) were observed at low cell density (3 × 10⁴ ± 10 × 10² cells μl⁻¹) and H₂ partial pressure (10–100 ml H₂). The influence of the H₂ partial pressure on the nanoparticle size and the possibility of size-tuned nanoparticles are presented.     

Toxicity and bio-effects of CuO nanoparticles on transgenic Ipt-cotton

This study investigated the effects of copper oxide nanoparticles (CuO NPs) on the growth and development of transgenic cotton harboring the Ipt gene, which encodes isopentenyl transferase (Ipt). Three concentrations of CuO NPs were evaluated: 10, 200, and 1000 mg·L^-1, each with three replicates. The height and the root length were 26.91% and 42.80% decreased after 10-day exposure with 1000 mg·L^-1 CuO NPs, respectively.In addition, less abundant on root hairs and lower in shoot biomass of Ipt-cotton when compared with the control group. The growth of Ipt-cotton was not affected by 10 mg·L^-1 CuO NPs, but a high concentration of CuO NPs promoted the absorption of Fe and Na into roots, and inhibited the production of phytohormones in Ipt-cotton. The CuO NPs increased the concentration of iPA in shoots, which can delay senescence. The extent of the increase in iPA in response to CuO NPs should be relative to the amount of Ipt immobilized onto the NPs in the plant tissue. To our knowledge, this is the first study to evaluate the phytotoxicity of CuO NPs to Ipt-transgenic cotton. These results establish a baseline for further research on the effects of nanoparticles on transgenic crops harboring the Ipt gene.     

Size-Dependent Antimicrobial Effects of Novel Palladium Nanoparticles

Investigating the interactions between nanoscale materials and microorganisms is crucial to provide a comprehensive, proactive understanding of nanomaterial toxicity and explore the potential for novel applications. It is well known that nanomaterial behavior is governed by the size and composition of the particles, though the effects of small differences in size toward biological cells have not been well investigated. Palladium nanoparticles (Pd NPs) have gained significant interest as catalysts for important carbon-carbon and carbon-heteroatom reactions and are increasingly used in the chemical industry, however, few other applications of Pd NPs have been investigated. In the present study, we examined the antimicrobial capacity of Pd NPs, which provides both an indication of their usefulness as target antimicrobial compounds, as well as their potency as potential environmental pollutants. We synthesized Pd NPs of three different well-constrained sizes, 2.0±0.1 nm, 2.5±0.2 nm and 3.1±0.2 nm. We examined the inhibitory effects of the Pd NPs and Pd²⁺ ions toward gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus) bacterial cultures throughout a 24 hour period. Inhibitory growth effects of six concentrations of Pd NPs and Pd²⁺ ions (2.5×10⁻⁴, 10⁻⁵, 10⁻⁶, 10⁻⁷, 10⁻⁸, and 10⁻⁹ M) were examined. Our results indicate that Pd NPs are generally much more inhibitory toward S. aureus than toward E. coli, though all sizes are toxic at ≥10⁻⁵ M to both organisms. We observed a significant difference in size-dependence of antimicrobial activity, which differed based on the microorganism tested. Our work shows that Pd NPs are highly antimicrobial, and that fine-scale (<1 nm) differences in size can alter antimicrobial activity.     

Tapered Fiber Probe Modified by Ag Nanoparticles for SERS Detection

A tapered optical fiber fabricated by a simple chemical etching method and modified with Ag nanoparticles (AgNPs) by chemical deposition was evaluated for surface-enhanced Raman scattering (SERS). The fiber probe was used for SERS measurements in both direct and remote scattering modes, yielding desired performance in both scattering configurations. The state of the obtained AgNPs made a significant contribution to the high sensitivity of SERS to Rhodamine 6G (R6G) molecules (down to a concentration of 10^?7 M), and the substrate had an analyst enhancement factor (AEF) on the order of ～10⁸. Meanwhile, the SERS intensity during the evaporation process was investigated, showing a good stability at the later stage of the evaporation process. The fiber SERS probes demonstrated good reproducibility with the average relative standard deviation (RSD) values being less than 0.2 for the major Raman peaks.     

Plasmonic and Nonlinear Optical Absorption Properties of Ag:ZrO2 Nanocomposite Thin Films

Ag nanoparticles (NPs) embedded in a zirconium oxide matrix in the form of Ag:ZrO₂ nanocomposite (NC) thin films were synthesized by using the sol–gel technique followed by thermal annealing. With the varying of the concentration of Ag precursor and annealing conditions, average sizes (diameters) of Ag nanoparticles (NPs) in the nanocomposite film have been varied from 7 to 20 nm. UV–VIS absorption studies reveal the surface plasmon resonance (SPR)-induced absorption in the visible region, and the SPR peak intensity increases with the increasing of the Ag precursor as well as with the annealing duration. A red shift in SPR peak position with the increase in the Ag precursor concentration confirms the growth of Ag NPs. Surface topographies of these NC films showed that deposited films are dense, uniform, and intact during the variation in annealing conditions. The magnitude and sign of absorptive nonlinearities were measured near the SPR of the Ag NPs with an open-aperture z-scan technique using a nanosecond-pulsed laser. Saturable optical absorption in NC films was identified having saturation intensities in the order of 10¹² W/m². Such values of saturation intensities with the possibility of size-dependent tuning could enable these NC films to be used in nanophotonic applications.     

Fungicidal synergistic effect of biogenically synthesized zinc oxide and copper oxide nanoparticles against Alternaria citri causing citrus black rot disease

Citrus black rot disease being caused by Alternaria citri is a major disease of citrus plants with 30–35% economic loss annually. Fungicides had not been effective in the control of this disease during last few decades. In the present study, antifungal role of green synthesized zinc oxide (ZnO) and copper oxide (CuO) nanoparticles (NPs) were studied against Alternaria citri. Alternaria citri was isolated from disease fruits samples and was identified by staining with lacto phenol cotton blue. Furthermore, CuO and ZnO NPs were synthesized by utilizing the lemon peels extract as the reducing and capping agent. Nanoparticles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. From the XRD data, the calculated size of CuO NPs was to be 18 nm and ZnO NPs was16.8 nm using Scherrer equation. The SEM analyses revealed the surface morphology of all the metal oxide NPs synthesized were rounded, elongated and or spherical in the shape. The zone of inhibition was observed to be 50 ± 0.5 mm by CuO NPs, followed by 51.5 ± 0.5 mm by ZnO NPs and maximum zone of antifungal inhibition was observed to be 53 ± 0.6 mm by mix metal oxide NPs. The results of minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of the synthesized nanoparticles showed that at the certain concentrations (80 mg ml^?1), these NPs were capable of inhibiting the fungal growth, whereas above that specified concentrations (100 mg ml^?1), NPs completely inhibited the fungal growth. Based on these findings, the green synthesized NPs can be used as alternative to fungicide in order to control the citrus black rot disease.     

Zn Subcellular Distribution in Liver of Goldfish (Carassius Auratus) with Exposure to Zinc Oxide Nanoparticles and Mechanism of Hepatic Detoxification

Zinc Oxide Nanoparticles (ZnO NPs) have attracted increasing concerns because of their widespread use and toxic potential. In this study, Zn accumulations in different tissues (gills, liver, muscle, and gut) of goldfish (Carassius auratus) after exposure to ZnO NPs were studied in comparison with bulk ZnO and Zn²⁺. And the technique of subcellular partitioning was firstly used on the liver of goldfish to study the hepatic accumulation of ZnO NPs. The results showed that at sublethal Zn concentration (2 mg/L), bioaccumulation in goldfish was tissue-specific and dependent on the exposure materials. Compared with Zn²⁺, the particles of bulk ZnO and the ZnO NPs appeared to aggregate in the environmentally contacted tissues (gills and gut), rather than transport to the internal tissues (liver and muscle). The subcellular distributions of liver differed for the three exposure treatments. After ZnO NPs exposure, Zn percentage in metal-rich granule (MRG) increased significantly, and after Zn²⁺ exposure, it increased significantly in the organelles. Metallothionein-like proteins (MTLP) were the main target for Zn²⁺, while MRG played dominant role for ZnO NPs. The different results of subcellular distributions revealed that metal detoxification mechanisms of liver for ZnO NPs, bulk ZnO, and Zn²⁺ were different. Overall, subcellular partitioning provided an interesting start to better understanding of the toxicity of nano- and conventional materials.