6 research outputs found

    Chemical Etching of Bovine Serum Albumin-Protected Au25 Nanoclusters for Label-Free and Separation-Free Ratiometric Fluorescent Detection of Tris(2-carboxyethyl)phosphine

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    This study describes a novel ratiometric fluorescent sensor based on chemical etching of gold nanocluster (GNCs) for label-free, separation-free determination of tris­(2-carboxyethyl)­phosphine (TCEP). TCEP was discovered to exhibit unusual chemical behavior toward fluorescent gold nanoclusters: it quenched the red fluorescent emission of the bovine serum album (BSA)-protected GNCs (GNCs@BSA) and simultaneously restored the blue fluorescent emission of the dityrosine (diTyr) residues of the BSA ligand. The TCEP-induced quenching of the fluorescent GNCs@BSA was investigated with the UV–vis adsorption spectrum, the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), inductively coupled plasma-mass spectrometry (ICP-MS) and X-ray photoelectron spectroscopy (XPS), revealing the chemical etching of the gold(0) core of the GNCs@BSA by TCEP. Furthermore, the ratio of the blue fluorescence intensity of the diTyr to the red fluorescence intensity of the GNCs@BSA was found to be dependent on TCEP concentration and showed a linear relationship in the TCEP concentration range of 500 nM to 50, 000 nM (<i>R</i><sup>2</sup> = 0.9943) with a limit of detection (LOD) of 130 nM, achieving the higher sensitivity over previous reports. This ratiometric sensor also showed superior selectivity for TCEP over certain common interferences including glutathione, 20 kinds of natural amino acids, and the oxidized form of TCEP. With the developed ratiometric method, the deproteinized human serum samples spiked with TCEP were analyzed with satisfactory results. In addition, it is worth noting that compared with conventional ratiometric fluorescent sensors, the ratiometric sensor developed in this study does not require external fluorophores, avoiding the additional derivation procedures

    Hidden Dityrosine Residues in Protein-Protected Gold Nanoclusters

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    The protein ligand shells of fluorescent protein-protected gold nanoclusters play an important role in the physiochemical properties and sensing applications of the nanoclusters. Recently, more and more attention has been paid to the investigation of the changes in the protein structure elements induced by the introduction of the nanoclusters in the proteins. In this work, the strategy of removal of the encapsulated gold nanoclusters from the protein ligand cages has been proposed, producing the “hollow” (or possibly “imprinted”) proteins for investigations for the first time. Nontoxic cysteamine was used as the etchant of the gold nanoclusters. With bovine serum albumin, lysozyme, and ovalbumin as model proteins, it was found that the luminescent dityrosine cross-links exist in the protein-protected gold nanoclusters, however, inner filter effect caused by the gold nanoclusters hide them

    In Situ Synthesis of CuS Nanoparticle-Doped Poly(<i>N</i>‑isopropylacrylamide)-Based Microgels for Near-Infrared Triggered Photothermal Therapy

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    Poly­(<i>N</i>-isopropylacrylamide)-<i>co</i>-(acrylic acid) (pNIPAm-<i>co</i>-AAc) microgels incorporated with CuS nanoparticles (CuSNPs) were synthesized and employed for near-infrared (NIR) triggered photothermal killing of cancer cells. Cu<sup>2+</sup> was enriched in the microgels through deprotonation of the pNIPAm-<i>co</i>-AAc microgels at high solution pH. CuSNPs were subsequently generated within the pNIPAm-<i>co</i>-AAc microgels upon exposure to heat and S<sup>2–</sup>. The solution of hybrid microgels showed an absorption peak in the NIR region (∼1000 nm). After demonstrating that the hybrid microgels were not cytotoxic, we showed that NIR excitation of the hybrid microgels could be used to kill HeLa cells. Almost 90% of the HeLa cells were killed when incubated with 400 μg/mL of the hybrid microgels and exposed to 808 nm laser light with a power density of 2 W/cm<sup>2</sup> for 10 min. While these materials show promise for photothermal therapy, they can also be incorporated into a hydrogel matrix that can be triggered to release small molecule drugs upon exposure to NIR wavelengths

    DataSheet1_Study on the seismic response of new staggered story isolated structure under different parameters.xls

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    The new staggered story isolated structure is developed according to the base-isolated structure and the mid-story isolated structure. Quantitative calculation and evaluation of seismic damage are very important for structural safety. In this paper, the seismic damage evaluation of a new staggered story isolated structure is studied by numerical simulation and damage index calculation. A new staggered story isolated structure is established, and the effects of different layers and different chassis areas on the seismic response of the structure are studied. When the position of the bottom isolated layer stays the same, the upper isolated layer is set at different layers, which is set to the top of the 3rd, 6th and 9th layers. When the upper isolated layer keeps at the top of the 3rd layer, the chassis area is set at a different area, which is 26 m × 26 m, 36 m × 36 m and 46 m × 46 m. The results show that the new staggered story isolated structure has good isolated effects under the ground motion. For the structure set upper isolation layer is lower, the inter-layer shear force, inter-layer acceleration and inter-layer displacement are reduced. The energy dissipation effect of the structure improves. The core tube is less damaged and the plastic hinge is smaller. With the increase of chassis area, the isolated effect of the part above the upper isolated layer is good, while the shear force and acceleration of the part below the upper isolated layer of the structure increase, the damage at the core tube changed little and the appearance of the plastic hinge increased. Under earthquakes, with the change in position of the upper isolated layer and the area of the chassis of the new staggered story isolated structure, the displacement, tensile stress and compressive stress of the isolated bearing still meet the requirements of the standard.</p

    Value of the Debris of Reduction Sculpture: Thiol Etching of Au Nanoclusters for Preparing Water-Soluble and Aggregation-Induced Emission-Active Au(I) Complexes as Phosphorescent Copper Ion Sensor

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    Chemical etching of gold by thiols has been known to be capable of generating nonluminescent gold­(I) complexes, e.g., in size-focusing synthesis of atomically precise gold nanoclusters (GNCs). These nonluminescent gold­(I) complexes have usually been considered as useless or worthless byproducts. This study shows a promising potential of thiol etching of GNCs to prepare novel water-soluble and phosphorescent gold­(I) materials for sensing application. First, cysteamine-induced etching of GNCs is used to produce nonluminescent oligomeric gold­(I)-thiolate complexes. Then, cadmium ion induces the aggregation of these oligomeric complexes to produce highly water-soluble ultrasmall intra-aggregates. These intra-aggregates can phosphoresce both in dilute aqueous solutions and in the solid phase. Studies on the effect of pH on their phosphorescent emission reveal the importance of the interaction between the amino groups of the ligands and cadmium ion for their phosphorescent emission property. Furthermore, Cu<sup>2+</sup> ion is found to quickly quench the phosphorescent emission of the intra-aggregates and simultaneously cause a Cu<sup>2+</sup>-concentration-dependent peak wavelength shift, enabling the establishment of a novel colorimetric sensor for sensitive and selective visual sensing of Cu<sup>2+</sup>
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