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Due to many special characteristics, zinc oxide nanoparticles (ZnO NPs) are widely used all over the world, leading to their wide distribution in the environment. However, the toxicities and mechanisms of environmental ZnO NP-induced changes of physiological processes and metabolism remain largely unknown. Here, we found that addition of dietary ZnO NPs disturbed hepatic Zn metabolism, increased hepatic Zn and lipid accumulation, downregulated lipolysis, induced oxidative stress, and activated mitophagy; N , N , N ', N '-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN, Zn 2+ ions chelator) alleviated high ZnO NP-induced Zn and lipid accumulation, oxidative stress, and mitophagy. Mechanistically, the suppression of mitochondrial oxidative stress attenuated ZnO NP-activated mitophagy and ZnO NP-induced lipotoxicity. Taken together, our study elucidated that mitochondrial oxidative stress mediated ZnO NP-induced mitophagy and lipotoxicity; ZnO NPs could be dissociated to free Zn 2+ ions, which partially contributed to ZnO NP-induced changes in oxidative stress, mitophagy, and lipid metabolism. Our study provides novel insights into the impacts and mechanism of ZnO NPs as harmful substances inducing lipotoxicity of aquatic organisms, and accordingly, metabolism-relevant parameters will be useful for the risk assessment of nanoparticle materials in the environment.

A core-shell QDs@mSiO 2 @y-AuNCs nanoprobe was prepared, and a new ratiometric fluorescent sensor for thiram detection was developed. The mechanism of thiram sensing was investigated using FTIR, surface-enhanced Raman, XPS spectra, etc. The sensing of thiram was mainly ascribed to the formation of Au-S bonds between thiram and Au atoms on y-AuNCs surface, resulting in the dissociation of 11-MUA ligand from the y-AuNCs surface and the charge transfer between thiram and y-AuNCs. In the ratiometric fluorescence detection of thiram based on QDs@mSiO 2 @y-AuNCs, a linear range of 0.5-60 ng/mL was obtained with a LOD of 0.19 ng/mL. Compared with the fluorescence detection based on y-AuNCs, the ratiometric fluorescence detection of thiram demonstrated 3-fold enhanced sensitivity. The improvement was ascribed to two aspects: the fluorescence emission of y-AuNCs was enhanced after they were loaded onto the QDs@mSiO 2 nanoparticles; the ratiometric detection mode provided more precise sensing. The detection of thiram can be completed immediately after mixing the nanoprobe with thiram. Good recoveries of thiram in apple and pear samples were achieved. All the above results demonstrated the high potential of this method in practical applications., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

In this work, a paper device consisted of a patterned paper chip, wicking pads, and a base was fabricated. On the paper chip, DNA-gold nanoparticles (DNA-AuNPs) were deposited and Hg 2+ ions could be adsorbed by the DNA-AuNPs. The formed DNA-AuNP/Hg 2+ nanozyme could catalyze the tetramethylbenzidine (TMB)-H 2 O 2 chromogenic reaction. Due to the wicking pads, a larger volume of Hg 2+ sample could be applied to the paper device for Hg 2+ detection and therefore the color response could be enhanced. The paper device achieved a cut-off value of 50 nM by the naked eye for Hg 2+ under optimized conditions. Moreover, quantitative measurements could be implemented by using a desktop scanner and extracting grayscale values. A linear range of 50-2000 nM Hg 2+ was obtained with a detection limit of 10 nM. In addition, the paper device could be applied in the detection of environmental water samples with high recoveries ranging from 85.7% to 105.6%. The paper-device-based colorimetric detection was low-cost, simple, and demonstrated high potential in real-sample applications.

HPV-induced cervical cancer is one of the most lethal cancers. Therefore, the development of a reliable and accurate method for the early diagnosis of HPV infections is highly important. Here, gold nanoparticles (AuNPs) were utilized as mass tags in an immuno-capture LI-MS assay for the detection of HPV marker proteins. Through the optimization of the amount of antibodies and surface charges on AuNPs, high antigen detection efficiency with minimal non-specific binding was achieved. With optimized antibody-conjugated AuNPs, low attomole amount of HPV proteins in HeLa cell lysate was quantified.

We report the first use of metallic nanozyme as colorimetric probe for Pb 2+ determination. The method is based on the surface leaching of Au@PtNP nanozyme by Pb 2+ -S 2 O 3 2- ions, accompanied by a decreased catalytic activity of the metallic nanozyme. To construct this colorimetric determination, the Pt deposition onto the AuNPs was carefully investigated and other experimental factors including kind of substrate and buffer were optimized. With increasing Pb 2+ concentration, the catalytic activity of the Au@PtNPs decreased gradually. As a result, the blue color at 650 nm from the oxidation of 3,3',5,5'-tetramethylbenzidine by H 2 O 2 faded gradually. A determination limit of 3.0 nM Pb 2+ with a linear range from 20 to 800 nM was obtained. The assay demonstrated negligible response to common metal ions even at elevated concentrations. This colorimetric method was applied to the determination of Pb 2+ ions spiked in lake water samples, and good recoveries (96.8-105.2%) were obtained. The above results indicate the potential application of metallic nanozymes in developing robust colorimetric assays. Graphical abstract Schematic representation of the surface leaching of Au@PtNP nanozyme by Pb 2+ -S 2 O 3 2- ions, accompanying the decreased catalytic activity of the metallic nanozyme.

In this work, core-shell Au@Pt nanocatalysts (Au@Pt NCs) with ultrathin Pt shell were synthesized and demonstrated high peroxidase-like activity. Thiocyanate ions (SCN - ) were found to effectively inhibit the peroxidase-like activity of Au@Pt NCs, and the mechanism was discussed by the characterization of TEM, DLS, EPR and XPS, etc. The inhibition of the catalytic activity of Au@Pt NCs by SCN - was mainly due to the decreased ability of the Au@Pt NCs for capturing • OH radicals and the increased ratio of Pt 2+ to Pt° on the surface of the Au@Pt NCs. A sensitive colorimetric detection of thiocyanate (SCN - ) was developed, based on the activity inhibition of Au@Pt NCs by SCN - . Interestingly, cystine modification of Au@Pt NCs was found to significantly improve the selectivity of SCN - recognition. After optimization, a colorimetric assay for SCN - was established with a detection limit of 5.0nM and a broad linear calibration over the range of 20nM to 40µM. This assay has the advantages of highly sensitive, selective and low-cost. Moreover, this assay demonstrated highly potential application in the quantitative determination of SCN - in water and raw milk samples., (Copyright © 2017. Published by Elsevier B.V.)

Using tri-sodium citrate as reducer, stable silver nanoparticles the size of about 20 nm were prepared by the microwave high pressure procedure with simplicity and rapidity. At pH 9.0, sliver nanoparticle was used to label goat anti-human IgG (GIgG) to obtain an immuno-nanosilver resonance scattering spectral probe (AgGIgG) for IgG. In pH 6.0 buffer solution and in the presence of polythylene glycol (PEG) and KCl, the immune reaction of IgG with AgGIgG took place, the silver nanoparticles released from AgGIgG produced aggregations, and the resonance scattering intensity at 485 nm (I(485 nm)) was enhanced greatly. The influence factors such as pH value, buffer solution volume, concentration of AgGIgG, KCl, PEG-4000, PEG-6000, PEG-10000 and PEG-20000, incubation temperature and time were considered, respectively. Under the conditions of 0.40 mL of pH 6.0 phosphate buffer solution, 1.20 mL of 9.8 microg x mL(-1) AgGIgG, 0.20 mL of 20% PEG-6000, 0.50 mL of 10% KCl, and ultrasonic irradiation for 25 min at room temperature, the increased intensity deltaI(485 nm), was proportional to the IgG concentration (c(IgG)) from 0.004 to 0.48 microg x mL(-1), with a detection limit of 2.4 ng x mL(-1). The regress equation was deltaI485 nm = 76.8c(IgG) + 4.7. The effect of foreign substances such as 20 microg x mL(-1) Ni2+, Fe2+, Pb2+ and BSA,60 microg x mL(-1) Cu2+, Ca2+ and HSA,60 microg x mL(-1) Mg2+ and Mn2+, 320 microg x mL(-1) Zn2+, glucose and urea on the deltaI(485 nm) was examined, respectively. Results showed that there was no interference. This assay showed high sensitivity and good selectivity for quantitative determination of IgG in human serum with satisfactory results. The analytical results were in agreement with that of the reference results.

Cell adhesion is a crucial issue for cytotoxicity or anticancer effectiveness for tumor cells. However, how both nanoparticles and drugs affect cell adhesion has not yet been defined. Herein, we report for the first time that gold nanoparticles and Paclitaxel can disrupt adhesion, as well as enhance apoptosis of HepG2 cell individually and synergistically, as observed by in situ measurement using quartz crystal microbalance (QCM). It was also found by MTT assay that gold nanoparticles of low cellular cytotoxicity enhance the antiproliferation and apoptosis of HepG2 cell induced by Paclitaxel. Those findings would be of great potential for biomedical application of nanoparticles.