1193-02-8Relevant articles and documents
Quantitative monitoring of hypoxia-induced intracellular acidification in lung tumor cells and tissues using activatable surface-enhanced raman scattering nanoprobes
Ma, Dandan,Zheng, Jing,Tang, Pinting,Xu, Weijian,Qing, Zhihe,Yang, Sheng,Li, Jishan,Yang, Ronghua
, p. 11852 - 11859 (2016)
Hypoxia is considered to contribute to pathophysiology in various cells and tissues, and a clear understanding about the relationship between hypoxia and intracellular acidification will help to elucidate the complex mechanism of glycolysis under hypoxia. However, current studies are mainly focused on overexpression of intracellular reductases accelerated by hypoxia, and the investigations focusing on the relationship between hypoxic degree and intracellular acidification remain to be explored. For this vacuity, we report herein a new activatable nanoprobe for sensing pH change under different degrees of hypoxia by surface-enhanced Raman spectroscopy (SERS). The monitoring was based on the SERS spectra changes of 4- nitrothiophenol (4-NTP)-functionalized gold nanorods (AuNR@4- NTP) resulting from the nitroreductase (NTR)-triggered reduction under hypoxic conditions while the as-generated 4-aminothiophenol (4-ATP) is a pH-sensitive molecule. This unique property can ensure the SERS monitoring of intracellular acidification in living cells and tissues under hypoxic conditions. Dynamic pH analysis indicated that the pH decreased from 7.1 to 6.5 as a function of different degrees of hypoxia (from 15 to 1%) due to excessive glycolytic activity triggered by hypoxia. Given the known advantages of SERS sensing, these findings hold promise in studies of pathophysiological pathways involving hypoxia.
In Situ Raman Monitoring and Manipulating of Interfacial Hydrogen Spillover by Precise Fabrication of Au/TiO2/Pt Sandwich Structures
Cheng, Jun,Guan, Zhiqiang,Li, Jian-Feng,Liu, Jing-Li,Qin, Si-Na,Ruan, Xiang-Yu,Tian, Zhong-Qun,Wei, Di-Ye,Wei, Jie,Xu, Hongxing,Yan, Hao,Zhang, Hua
, (2020)
The spillover of hydrogen species and its role in tuning the activity and selectivity in catalytic hydrogenation have been investigated in situ using surface-enhanced Raman spectroscopy (SERS) with 10 nm spatial resolution through the precise fabrication
Site-specific growth of Au-Pd alloy horns on Au nanorods: A platform for highly sensitive monitoring of catalytic reactions by surface enhancement raman spectroscopy
Huang, Jianfeng,Zhu, Yihan,Lin, Ming,Wang, Qingxiao,Zhao, Lan,Yang, Yang,Yao, Ke Xin,Han, Yu
, p. 8552 - 8561 (2013)
Surface-enhanced Raman scattering (SERS) is a highly sensitive probe for molecular detection. The aim of this study was to develop an efficient platform for investigating the kinetics of catalytic reactions with SERS. To achieve this, we synthesized a novel Au-Pd bimetallic nanostructure (HIF-AuNR@AuPd) through site-specific epitaxial growth of Au-Pd alloy horns as catalytic sites at the ends of Au nanorods. Using high-resolution electron microscopy and tomography, we successfully reconstructed the complex three-dimensional morphology of HIF-AuNR@AuPd and identified that the horns are bound with high-index {11l} (0.25 a strong SERS effect at the rod ends, making HIF-AuNR@AuPd an excellent bifunctional platform for in situ monitoring of surface catalytic reactions. Using the hydrogenation of 4-nitrothiophenol as a model reaction, we demonstrated that its first-order reaction kinetics could be accurately determined from this platform. Moreover, we clearly identified the superior catalytic activity of the rod ends relative to that of the rod bodies, owing to the different SERS activities at the two positions. In comparison with other reported Au-Pd bimetallic nanostructures, HIF-AuNR@AuPd offered both higher catalytic activity and greater detection sensitivity.
Fabrication of a Flowerlike Ag Microsphere Film with Applications in Catalysis and as a SERS Substrate
Dai, Qijun,Li, Lu,Wang, Chungang,Lv, Changli,Su, Zhongmin,Chai, Fang
, p. 2835 - 2840 (2018)
Three-dimensional flowerlike Ag microstructures were assembled in situ on a substrate to fabricate Ag microflower (Ag MF) films. The morphology and size of the Ag MFs can be easily controlled by varying the reaction time. The mechanism of growth of Ag MFs was investigated by SEM. The shape evolution revealed that the Ag MFs are assembled from thin nanosheets composed of Ag nanoparticles (NPs), and the elemental composition of the NPs was evidenced by energy-dispersive X-ray spectroscopic analysis. The potential of the film as a catalyst in the reduction of nitrophenols was investigated. The reusability of the catalyst was estimated by recycling catalysis of 4-nitrophenol. Moreover, the Ag MF film could be used as a versatile substrate for surface-enhanced Raman scattering (SERS) for detection of Rhodamine 6G with a detection limit as low as 1 × 10–7 m. The results demonstrated that the Ag MF film exhibits excellent SERS enhancement ability and catalytic activity.
Insight into the mechanism of gold-catalyzed reduction of nitroarenes based on the substituent effect and: In situ IR
Wang, Cui,Zou, Wei,Wang, Jiasheng,Ge, Yuzhen,Lu, Rongwen,Zhang, Shufen
, p. 3865 - 3871 (2017)
A study is presented here on the mechanistic pathway of catalytic reduction of nitroarenes with diverse substituent groups in the presence of ultra-small gold nanoparticles and NaBH4. The kinetic data based on the substituent effect and the Hammett plot, together with analyses of intermediates, revealed that this reaction followed a direct route and that all of the reaction steps were rapid without accumulation of intermediates. In particular, in situ IR was found to be an effective method for the real-time monitoring of this model reduction in our catalytic system and confirmed the presence of a hydroxylamine intermediate. These results will provide a new insight into the mechanism of gold-catalyzed reduction of nitroarenes and offer a reference for future mechanism tests of heterogeneous nanocatalysis.
Synthesis of highly-branched Au@AgPd core/shell nanoflowers for in situ SERS monitoring of catalytic reactions
Lai, Yujian,Dong, Lijie,Liu, Rui,Lu, Shaoyu,He, Zuoliang,Shan, Wanyu,Geng, Fanglan,Cai, Yaqi,Liu, Jingfu
, p. 2437 - 2441 (2020)
Alloy and small size nanostructures are favorable to catalytical performance, but not to surface-enhanced Raman spectroscopy (SERS) applications. Integrating SERS and catalytic activity into the nanocrystals with both alloy and small size structures is of great interest in fabrication of SERS platform to in situ monitor catalytical reaction. Herein, we report a facile method to synthesize Au@AgPd trimetallic nanoflowers (Au@AgPd NFs) with both SERS and catalytic activities, through simultaneous selective growth of Ag and Pd on Au core to form highly-branched alloy shell. These nanocrystals have the properties of small sizes, defects abundance, and highly-dispersed alloy shell which offer superior catalytic activity, while the merits of monodisperse, excellent stability, and highly-branched shell and core/alloy-shell structure promise the enhanced SERS activity. We further studied their growth mechanisms, and found that the ratio of Ag to Pd, sizes of Au core, and surfactant cetyltrimethylammonium bromide together determine this special structure. Using this as-synthesized nanocrystals, a monolayer bifunctional platform with both SERS and catalytical activity was fabricated through self-assembly at air/water interface, and applied to in situ SERS monitoring the reaction process of Pd-catalyzed hydrogenation of 4-nitrothiophenol to 4-aminothiophenol.
Fabrication of monodispersed Au@Ag bimetallic nanorod-loaded nanofibrous membrane with fast thermo-responsiveness and its use as a smart free-standing SERS substrate
Chen, Siyuan,Wang, Liying,Dong, Xu,Liu, Xiaoyun,Zhou, Jianfeng,Yang, Jianmao,Zha, Liusheng
, p. 48479 - 48488 (2016)
A novel type of metal nanoparticle-loaded smart nanofibrous membrane with fast thermo-responsiveness was fabricated by electrospinning an aqueous solution containing poly(N-isopropylacrylamide-co-N-hydroxymethylacrylamide) and monodispersed Au@Ag bimetallic nanorods with a core-shell structure, followed by heat treatment. The results obtained by electron microscopy show that the anisotropic nanoparticles are oriented along the axes of its constituent nanofibers. The membrane produced has high stability in aqueous media and remarkable thermo-responsiveness. It takes less than 10 seconds to reach its deswelling or swelling equilibrium state with the temperature alternating between 25 °C and 50 °C. The smart nanofibrous membrane with macroscopic mechanical strength can be used as a free-standing surface-enhanced Raman scattering (SERS) substrate with high Raman signal reproducibility for quantitative analysis, and its SERS efficiency can be readily elevated by raising the detection temperature across its phase transition temperature due to its fast thermo-response rate. Particularly, since the composite nanofibrous membrane possesses catalytic properties toward the reduction of 4-nitrothiophenol to 4-aminothiophenol by NaBH4, it has the ability to act as an in situ SERS monitor for the reaction, and it was deduced from the detected intermediate that the reaction proceeds via a condensation reaction route.
In-situ SHINERS Study of the Size and Composition Effect of Pt-based Nanocatalysts in Catalytic Hydrogenation
Wang, Chen,Chen, Xing,Chen, Tian-Ming,Wei, Jie,Qin,Zheng, Ju-Fang,Zhang, Hua,Tian, Zhong-Qun,Li, Jian-Feng
, p. 75 - 79 (2020)
Understanding the structure-activity relationship of catalytic reactions at a molecular level still remains a great challenge. Herein, shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) is employed to in-situ study the catalytic hydrogenation of para-nitrothiophenol (pNTP) on Pt-based nanocatalysts with different size and composition. The nanocatalysts are assembled on pinhole-free shell-isolate nanoparticles (SHINs), which work as Raman amplifiers to enhance the Raman signals of species on the catalysts, allowing the in-situ monitoring of catalytic reactions carried out on the catalysts. Using this strategy, we find that the catalytic activity of the Pt nanocatalysts shows a volcanic trend with the Pt size, and that PtM (M=Ni or Cu) bimetallic nanocatalysts display much higher performance compared with Pt due to better activation of the nitro group. This work demonstrates that SHINERS is a promising technique for in-situ study of nanocatalysis thus can deepen the understanding of the behaviors of different catalysts.
A Common, Facile and Eco-Friendly Method for the Reduction of Nitroarenes, Selective Reduction of Poly-Nitroarenes and Deoxygenation of N-Oxide Containing Heteroarenes Using Elemental Sulfur
Cerecetto, Hugo,Romero, Angel H.
supporting information, (2020/03/23)
A transition metal-free, environment-friendly and practical protocol was developed either for the reduction of nitroarenes or for the deoxygenation of N-oxide containing heteroarenes. The reaction proceeded with the use of a non-toxic and cheap feedstock as elemental sulfur in aqueous methanol under relatively mild conditions. Green chemistry credentials were widely favorable compared to traditional and industrial protocols with good E-factors and a low production of waste. The strategy allowed the efficient reduction of a large variety of substituted-nitroarenes including various o-nitroanilines as well as selective reduction of various poly-nitroarenes in excellent yields with a broad substrate scope. The protocol was successfully extended to the deoxygenation of some N-oxide containing heteroarenes, like benzofuroxans, phenazine N,N'-dioxides, pyridine N-oxides, 2H-indazole N1-oxides, quinoxaline N1,N4-dioxides and benzo[d]imidazole N1,N3-dioxides. A gram-scale example for the synthesis of luminol, in green conditions, was reported. A solid mechanism of reaction was proposed from experimental evidences.
