查找使用阿拉丁产品的科研文献

Electrochemical Aptasensor Based on ZnO-Au Nanocomposites for the Determination of Ochratoxin A in Wine and Beer

Sai Zhang,Yahui Wang,Qinglin Sheng,Tianli Yue

Ochratoxin A(OTA) is positively correlated with an increased risk of developing cancer in nephrotoxic and hepatotoxic patients. Therefore, it is of great significance for the highly sensitive, highly selective, and timely detection of OTA. We described here an electrochemical aptasensor for OTA analysis, which took advantage of the favorable properties of gold nanoparticles (AuNPs) functionalized zinc oxide (ZnO) composites and the intercalative binding between methylene blue (MB) and nucleic acid. There were two label-free aptamers: one to capture OTA and another serving as complementary DNA (cDNA), enabling connection to the ZnO-Au composite’s immobilized electrode. Once OTA was present, the aptamer could capture OTA and detach from the electrode interface, thus, preventing MB from accessing electrode surface for efficient electron transfer; a decreased peak current was monitored by differential pulse voltammetry. The aptasensor presented nice analytical performance for OTA detection in the range of 0.1–30,000 pg·mL−1, with a detection limit of 0.05 pg·mL−1. Moreover, the developed biosensor could be applied to actual sample (wine and beer) analysis.Keywords:food safety;electrochemical aptasensor;intercalative binding;zinc oxide-gold composites;Ochratoxin A

Nano-Au supported on CeO2 for plasma catalytic degradation of n-undecane: Enhancement of activity and stability

Tongtong Xia,Zuliang Wu,Ehao Gao,Jiali Zhu,Shuiliang Yao,Jing Li

n -Undecane (C11) is a typical alkane pollutant, accounting for 6 % of the total volatile organic compounds (VOCs) emitted from the printing industry in China. A dielectric barrier discharge (DBD) reactor coupled with a catalyst of abundant oxygen vacancies prepared by Au nanoparticles 100 % loading on CeO 2 was developed for the plasma catalytic degradation of C11. Compared with CeO 2 , CeO 2 /γ-Al 2 O 3 , Au/γ-Al 2 O 3 , and Au/CeO 2 /γ-Al 2 O 3 , Au/CeO 2 exhibited significantly higher C11 oxidation performance with 98.8 % C11 conversion and 97.9 % COx selectivity. The strong interaction between nanosized Au and CeO 2 enhanced the ratios of Ce 3+ /(Ce 3+ +Ce 4+ ) and Au + /(Au + +Au 0 ), resulting in the formation of abundant oxygen vacancies with the highest band gap energy, which facilitated C11 oxidation. In addition, the reservation of reactive oxygen species generated by gas discharges on Au/CeO 2 catalyst synergistically promoted C11 complete oxidation, thus improving the oxidation stability within 600 min with stable C11 conversion and COx selectivity. This work presents an effective strategy to regulate the performance of catalysts for VOCs oxidation, and demonstrates that the plasma catalytic degradation of VOCs is feasible.

A vivid Au-porous anodic alumina composite film with the inverted taper structure for label-free detection

Yu Zhumin,Zhao Kai,Li Lin,Ye Changqing,Dong Yuxiang,Song Yanlin

Localized surface plasmon resonance (LSPR) has been widely used in medical detection because of its time effectiveness, non-invasiveness, high sensitivity, and relatively simple fabrication process. Porous anodic alumina (PAA) can be regarded as a plasma substrate for label-free detection due to its unique two-dimensional structure. In this work, a vivid Au-PAA composite film with the inverted taper structure was developed by multi-step anodic oxidation and pore-widening processes followed by magnetron sputtering with Au nanoparticles (AuNPs). The highly saturated and bright structural color was generated by the synergistic effect of photonic and plasmonic modes. Interestingly, various Au-PAA composite films with structural colors altering from purple to red were obtained via adjusting the height/diameter ratio of PAA. Benefiting from the inverted taper structure, light trap characteristics were effectively enhanced by increasing the incident light and reducing the diffuse light. In addition, a finite difference time domain (FDTD) model was proposed to predict the relationship between the reflectance peak and the height of the composite film, and the simulated data were in good agreement with the experimental results. As a proof of concept, label-free detections of various reagents (water, ethanol, glycol, glycerol, and glucose), the concentration of glucose (refractive index sensitivity of 376 nm/RIU, RIU: refractive index unit), and thrombin (detection limit of 0.1 × 10 −7 mol/L) were realized by the Au-PAA composite film. This vivid Au-PAA composite film provides a very powerful tool for in-situ label-free bio-detection.

Au Catalyzing Control Release NO in vivo and Tumor Growth-Inhibiting Effect in Chemo-Photothermal Combination Therapy

Ying Zhang,Tianfu Zhou,Jian Li,Nuo Xu,Mingze Cai,Hong Zhang,Qinfu Zhao,Siling Wang

Au@Ag Core-shell Nanorods Self-assembled on Polyelectrolyte Multilayers for Ultra-High Sensitivity SERS Fiber Probes

Wang Wenbo,Xiong Wenhao,Long Yuting,Li Hong

We demonstrated a chemical process in the fabrication of a SERS fiber probe with an ultrahigh sensitivity. The synthesis was carried out by preparing Au@Ag core-shell nanorods (Au@Ag-NRs) self-assembled on polyelectrolyte (PE) multilayers, for which Au@Ag-NRs were controlled by adjusting the silver layer thickness. The effect of silver layer thickness of Au@Ag-NRs on the SERS performance of the fiber probe was investigated. The SERS fiber probe shows the best performance when the silver layer thickness is controlled at 8.57 nm. Under the condition of optimizing silver layer thickness, the fiber probe exhibits ultra-high sensitivity ( i e , 10 −10 M crystalline violet, CV), good reproducibility ( i e , RSD of 3.5%) and stability. Besides, electromagnetic field distribution of the SERS fiber probe was also investigated. The strongest enhancement is found within the core of fiber, whereas a weakened electromagnetic field exists in the fiber cladding layer. The SERS fiber probe can be a good candidate in ultra-trace detection for biomedical and environmental areas.

Rational design of a MOF@Au@COF catalyst with electron synergy for the reduction of 4-nitrophenol

Shangjin Liu,Chunfeng Mao,Chenghan Yang,Pengda Hong,Min Zhu,Yuming Zhou,Yiwei Zhang

4-Nitrophenol (4-NP) usually exists in soil and groundwater, which causes great harm to the environment and human health. Removal of 4-nitrophenol has become the focus of research. Herein, a smart synthetic strategy of NH2-MIL-88B(Fe)@Au@Covalent Organic Frameworks (COFs) is proposed for the first time. NH2-MIL-88B(Fe)@Au@COFs are composed of NH2-MIL-88B(Fe) as the core and COFs as the shell with Au nanoparticles. Au nanoparticles in NH2-MIL-88B(Fe)@Au@COFs exhibit good dispersion and thermal stability due to amino group immobilization on NH2-MIL-88B(Fe). The core–shell structure, high thermal stability and highly dispersed active sites of NH2-MIL-88B(Fe)@Au@COFs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), and so on. To the best of our knowledge, 4-nitrophenol was reduced to 4-aminophenol using NH2-MIL-88B(Fe)@Au@COFs as the catalyst, NaBH4 as the reductant and 4-nitrophenol as the raw material at room temperature. The catalyst has high catalytic activity and can be used repeatedly for the reduction of 4-nitrophenol under the cooperation of Fe and Au electrons. In addition, the kinetics and mechanism of catalytic reduction were discussed in detail. Multi-functional materials constructed using metal organic frameworks (MOFs) and COFs provide a basis for the application and expansion of new porous materials.

Cooperative Amplification of Au@FeCo as Mimetic Catalytic Nanozymes and Bicycled Hairpin Assembly for Ultrasensitive Electrochemical Biosensing

Weixiang Huang,Chunli Yang,Jiaxi Gao,Jingjing Ye,Ruo Yuan,Wenju Xu

Exploring the cooperative amplification of peroxidase-like metal nanocomposites and cycled hairpin assembly is intriguing for sensitive bioanalysis. Herein, we report the first design of a unique electrochemical biosensor based on mimicking Au@FeCo nanozymes and bicycled hairpin assembly (BHA) for synergistic signal amplification. By loading the enzyme-like FeCo alloy in Au nanoparticles (AuNPs), the as-synthesized Au@FeCo hybrids display great improvement of electronic conductivity and active surface area and excellent mimic catalase activity to H2O2 decomposition into •OH radicals. The immobilization of Au@FeCo in an electrode sensing interface is stabilized via the resulting electrodeposition in HAuCl4 while efficiently accelerating the electron transfer of electroactive ferrocene (Fc). Upon the immobilization of a helping hairpin (HH) via Au–S bonds, a specific DNA trigger (T*) is introduced to activate BHA operation through competitive strand displacement reactions among recognizing hairpin (RH), signaling hairpin (SH), and HH. T* and RH are rationally released to catalyze two cycles, in which the transient depletion of dsDNA intermediates rapidly drives the progressive hairpin assemblies to output more products SH·HH. Thus, the efficient amplification of Au@FeCo mimic catalase activity combined with BHA leads to a significantly increased current signal of Fc dependent on miRNA-21 analogous to T*, thereby directing the creation of a highly sensitive electrochemical biosensor having applicable potential in actual samples.

Preparation of highly selective polyether sulfone /polym-phenylenediamine membrane for recovery of Au(III) from aqueous solutions

Zhongmin Feng,Chuanyu Zhu,Yupu Meng,Zhuqing Wang

A non-solvent-induced phase separation method was used to synthesize easily separable membrane materials from polyether sulfone and polym-phenylenediamine to achieve selective recovery of Au from e-waste solutions. The optimum conditions, adsorption capacity, and selectivity of the polyether sulfone/polym-phenylenediamine membrane were investigated by adsorption experiments. The maximum adsorption capacity of the PES/PmPD membrane to Au(III) within 4 h at 30 °C with optimal pH of 1 was 582.75 mg/g. The adsorption process follows the quasi-second-order adsorption isotherm. The adsorption agent was characterized by XPS and XRD to understand the recovery mechanism of Au(III) by PES/PmPD membrane. In addition, PES/PmPD membranes were single-selective for Au(III) in a variety of natural water bodies and highly acidic conditions. Therefore, the thin membrane material has great potential for recycling Au(III) from waste e-waste.

Enhanced Sum Frequency Generation for Monolayers on Au Relative to Silica: Local Field Factors and SPR Effect

Bolin Li,Yonghao Ma,Xiaofeng Han,Pengcheng Hu,Xiaolin Lu

Using metals as signal magnified substrates, surface plasmon-enhanced sum frequency generation (SFG) vibrational spectroscopy is a promising technique to probe weak molecular-level signals at surfaces and interfaces. In this study, the vibrational signals of the n-alkane monolayer on the gold (Au) and silica substrates are investigated using the broadband femtosecond SFG. The enhancement factors are discovered to be up to ∼1076 and ∼31 for the methyl symmetric and asymmetric stretching (ss and as) modes of the monolayer, respectively. By systematically analyzing the second-order nonlinear susceptibility tensor components (χijks), the Fresnel coefficients (Fijks), and the surface plasmon resonance (SPR) effect, we find that the interplay between Fijk and χijk terms and the SPR effect dominate the SFG signal enhancement. Our study reveals that the relative contributions of different influencing factors (i.e., Fresnel coefficients and SPR) to the SFG signal enhancement provide an approach to interpreting enhanced SFG vibrational signals detected from probe molecules on distinct substrates and may finally guide the design of the experimental methodology to improve the detection sensitivity and signal-to-noise ratio.

Synergy in magnetic NixCo1Oy oxides enables base-free selective oxidation of 5-hydroxymethylfurfural on loaded Au nanoparticles

Hao Zhang,Yinghao Wang,Qizhao Zhang,Bang Gu,Qinghu Tang,Qiue Cao,Kun Wei,Wenhao Fang

The base-free aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) in water is recognized as an important and sustainable upgrading process for cellulosic carbohydrates. However, selectivity control still remains a challenge. Here, we disclose that the unique synergy in magnetic Ni x Co 1 O y ( x  = 1, 3 and 5) bimetallic oxides can induce reactive oxygen defects and simultaneously stabilize small-sized metallic Au nanoparticles in the Au/Ni x Co 1 O y catalysts. Such catalytic features render effective adsorption and activation of O 2 , OH and C O groups, realizing selective oxidation of HMF to FDCA . On a series of magnetic Au/Ni x Co 1 O y catalysts with almost identical Au loadings (ca. 0.5 wt%) and particle sizes (ca. 2.7 nm), the variable Ni/Co molar ratios give rise to the tunable electron density of Au sites and synergistic effect between NiO and CoO y . The initial conversion rates of HMF and its derived intermediates (i.e., DFF, HMFCA and FFCA) show a volcano-like dependence on the number of oxygen defects (i.e., O 2 − and O − ) and electron-rich Au 0 sites. The optimum Au/Ni 3 Co 1 O y catalyst exhibits a highest productivity of FDCA (12.5 mmol FDCA mol Au - 1 h −1 ) among all the Au catalysts in the literature and achieves > 99% yield of FDCA at 120 °C and 10 bar of O 2 . In addition, this catalyst can be easily recovered by a magnet and show superior stability and reusability during six consecutive cycling tests. This work may shed a light on Au catalysis for the base-free oxidation of biomass compounds by smartly using the synergy in bimetallic oxide carriers.

Plasmon-dependent photophysical preparation of reversible Au@safranine T core-shell nanostructures with edit and erase features

Qian Li,Yue Xu,Wei He,Yuan Fang Li,Peng Fei Gao,Cheng Zhi Huang

Core-shell materials have superior properties over their single-component counterparts, and thus how to develop a new type of core-shell structure deserves much hard work. Herein, a plasmon-dependent photophysical (PDPP) process was developed to prepare [email protected] T core-shell nanostructures with reversible properties, wherein Safranine T (ST) was at first adsorbed on the surface of negatively charged gold nanospheres (AuNSs) through the electrostatic attraction and then controllably deposited by adjusting plasmonic illumination. The whole PDPP process was monitored in real-time via dark field microscopy (DFM) imaging system, verifying that plasmon-dependent light-matter interaction occurs. The as-prepared [email protected] nanostructures were then successfully applied for a reversible process of edit and erase that was suitable for encryption application with nanosized precision. This research showed that the PDPP process has high promise for developing precise structures of new materials, particularly those through nanoprocessing and nanooperation.

Bi5O7Br-nanotube@Au-nanoparticle core-shell assembly for high signal-to-noise ratio SERS detection of adenine

Ran Feng,Jiazhi Meng,Hualei Yuan,Xu Zhang,Chunlang Gao,Chaogang Ban,Yizhong Guo,Kaiwen Wang

Cancers, Down’s syndrome, Alzheimer’s and other diseases of gene mutation always occur with anomalous changes of DNA nucleic acid base. Therefore, the development of highly sensitive and reproducible nucleic acid sensors that based upon surface enhanced Raman scattering (SERS) is of immense interest for clinical medical analysis and diagnosis. Herein, a rationally designed core-shell assembly of Au nanoparticle wrapped with Au doped Bi 5 O 7 Br nanotube with eliminated fluorescent background and notable chemical enhancement effect was exploited and served as a SERS sensor for detection of adenine. Especially, we found the fluorescent background was remarkably suppressed in Raman spectra by introducing Au element into Bi 5 O 7 Br. The sensor exhibited a maximum SERS enhancement factor of up to 5.45 × 10 7 and a detection limit as low as 10 −11 M after constructing Au nanoparticle/Au atom doped Bi 5 O 7 Br heterojunction . More importantly, good reproducibility and long term stability under work condition were achieved. To gain in-depth understanding into chemical mechanism (CM) of the Raman signal enhancement, density functional calculations (DFTs) were combined with atom-specific model derived via aberration corrected transmission electron microscope (AC-TEM) to demonstrate the enhanced charge transfer (CT) and substrate-adsorbate adsorption. The doping and coupling strategy holds the potential to fabricate high signal-to-noise ratio SERS sensors for other molecule detection.