13 research outputs found

    Epidermal Penetration of Gold Nanoparticles and Its Underlying Mechanism Based on Human Reconstructed 3D Episkin Model

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    Nanomaterials are widely used in diverse aspects, and their translocation behavior through the skin would be helpful in understanding the corresponding exposure risks. To reveal how surface functionalization of nanoparticles influences the skin penetration, three kinds of gold nanoparticles (GNPs) with negatively, neutrally, and positively charged surfaces, that is, cetyltrimethylammonium bromide-coated GNPs (CTAB@GNP), polyvinylpyrrolidone-coated GNPs (PVP@GNP), and citrate-coated GNPs (Citrate@GNP), were studied using human reconstructed 3D Episkin model. The measurement of Au distribution in diverse layers of the Episkin model indicated that all three GNPs could penetrate through the epidermis, wherein CTAB@GNP with positive surface charges exhibited the highest efficiency in skin penetration. The upward osmosis of the medium proteins confirmed the occurrence of skin permeation induced by GNP treatment, and the lipid network in the stratum corneum was also altered as the consequence of GNP exposure. When compared to Citrate@GNP and PVP@GNP, CTAB@GNP significantly compromised the tight junction of keratinocytes, causing paracellular penetration of nanoparticles. The existence of cytoplasmic gold showed the transcytosis pathway through endocytosis and exocytosis processes was the main epidermic penetration behavior of the tested GNPs. The study on GNP penetration process through the 3D Episkin model has, on one hand, offered a promising approach to evaluate the translocation process of nanoparticles across the skin, and, on the other hand, provided mechanism explanation for diverse penetration behaviors of GNPs with different surface charges. The findings herein would be of great help in nanotechnology improvement and nanosafety evaluation

    Zinc Oxide Supported <i>trans</i>-CoD(<i>p</i>‑Cl)PPCl-Type Metalloporphyrins Catalyst for Cyclohexane Oxidation to Cyclohexanol and Cyclohexanone with High Yield

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    Direct functionalization of saturated C–H bonds by metalloporphyrin catalysts is among the topical and challenging areas within the chemical industry and synthetic chemistry. In this work, supported CoD­(<i>p</i>-Cl)­PPCl metalloporphyrin catalysts were prepared and characterized. It has been found that the CoD­(<i>p</i>-Cl)­PPCl/ZnO catalyst shows better catalytic activity than the supported catalyst (ZrO<sub>2</sub>, MCM-41, kaolin, Zr­(OH)<sub>2</sub>, and boehmite (BM)) in cyclohexane oxidation with dioxygen. The effects of the reaction pressure, reaction temperature, and reaction time on the catalytic activity were considered by the supported CoD­(<i>p</i>-Cl)­PPCl/ZnO catalyst. The CoD­(<i>p</i>-Cl)­PPCl/ZnO catalyst can be facilely recovered and was recycled up to seven times without a significant decrease in catalytic performance. The average cyclohexane conversion and selectivity to KA oil are 10.98% and 84.34%, respectively, and the turnover number is 2.10 × 10<sup>7</sup>

    Influence of the Surface Functional Group Density on the Carbon-Nanotube-Induced α‑Chymotrypsin Structure and Activity Alterations

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    Because of the special properties of carbon nanotubes (CNTs), their applications have been introduced to many fields. The biosafety of these emerging materials is of high concern concomitantly. Because CNTs may initially bind with proteins in biofluids before they exert biological effects, it is of great importance to understand how the target proteins interact with these exogenous nanomaterials. Here we investigated the interaction between α-chymotrypsin (α-ChT) and carboxylized multiwalled CNTs in a simulated biophysical environment utilizing the techniques of fluorescence, UV–vis, circular dichroism spectroscopy, ζ potential, atomic force microscopy, and bicinchoninic acid analysis. It was demonstrated that CNTs interacted with α-ChT through electrostatic forces, causing a decrement in the α-helix and an increment in the β-sheet content of the protein. The protein fluorescence was quenched in a static mode. The increase in the surface modification density of CNTs enhanced the protein absorption and decreased the enzymatic activity correspondingly. α-ChT activity inhibition induced by CNTs with low surface modification density exhibited noncompetitive characteristics; however, a competitive feature was observed when CNTs with high surface modification density interacted with the protein. An increase of the ionic strength in the reaction buffer may help to reduce the interaction between CNTs and α-ChT because the high ionic strength may favor the release of the protein from binding on a CNT surface modified with functional groups. Accordingly, the functionalization density on the CNT surface plays an important role in the regulation of their biological effects and is worthy of concern when new modified CNTs are developed

    Topological organization of ABCA4 and conservation analysis.

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    <p>(A) Protein alignment showed conservation of residues ABCA4 Y808X and G607R across nine species. These two mutations occured at an evolutionarily conserved amino acid. The ABCA4 mutation G607R occured in the NBD1 while Y808X occured in the disc lumen region between TMD1. (B) Topological organization of ABCA4 in the disc membrane was shown. The domain organization included exocytoplamic domain (ECD), nucleotide binding domain (NBD) and transmembrane domain (TMD).</p

    Pedigree of family 2048 with Stargardt.

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    <p>Solid symbols indicated affected individuals. Open symbols indicated unaffected individuals and arrow indicates the proband.</p

    Mutation identification of <i>ABCA4</i> gene.

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    <p>Electropherogram analysis of <i>ABCA4</i> in family 2048 showing the compound heterozygous mutations (c.C2424G and c.G1819A) co-segregated with the phenotype. II1 and II2 patients harbored compound heterozygous c.C2424G and c.G1819A mutations of the <i>ABCA4</i> gene. c.C2424G mutation was carried by the mother I2 while c.G1819A mutation was carried by the father I1.</p

    Representative photographs of patients of family 2048.

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    <p>(A) Fundus photographs showing pigment mottling and yellow-white flecks in both maculae. (B) Fluorescein angiography (FA) images showing the hyperfluorescent flecks extended to the midperipheral retina and fluorescence blocking by the pigment mottling in the mcular. (C) mfERG records showing severe depressed central waveform and significant paracentral/pereferral loss of retinal response. (D) Macular OCTs showing hyper-reflective deposits within the RPE layer and the level of the outer segments of the photoreceptors, thinning of the retinal outer layers and enhanced choroidal reflectivity associated with overlying atrophic retina.</p
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