One‐Pot Hydrothermal Synthesis of Highly Fluorescent Polyethyleneimine‐capped Copper Nanoclusters for Specific Detection of Rifampicin

Nai-Di Tan,Jian-Hang Yin,Yaqing Yuan,Lei Meng,Na Xu 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.5

Herein, a novel bright?green and highly fluorescent polyethyleneimine capped copper nanoclusters (CuNCs@PEI) has been hydrothermally synthesized, which is employed as a fluorescence probe to determine rifampicin. Under optimum synthetic conditions, the morphology, surface chemistry and optical features of resulting CuNCs@PEI are well characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, UV?Vis absorption spectra, transient and steady?state fluorescence. In comparison to previous reports, the new species with a larger diameter of approximately 3 nm exhibit higher fluorescence quantum yield (QY) up to nearly 10.7%, and demonstrate tolerability to extreme pH, high ionic strengths as well as long?term UV irradiation. These excellent optical properties ascribe to unique grain size and surface chemical features of products, which are further discussed in this work. In addition, we employed as?prepared CuNCs@PEI to detect rifampicin based on fluorescence quenching phenomenon. The fluorescence intensity of probe is linearly proportional to rifampicin over the concentration rage from 0 to 20??M, where the limit of detection (LOD) is 50?nM. Besides, this probe can be also used to assay rifampicin in serum samples with satisfactory recoveries.

Selective Detection of Trace Metronidazole by Using a Magnetic Molecularly Imprinted Polymer-based Fluorescent Probe

Nai-Di Tan,Chengwu Lan,Jian-Hang Yin,Lei Meng,Na Xu 대한화학회 2020 Bulletin of the Korean Chemical Society Vol.41 No.1

A magnetic molecularly imprinted polymer-based fluorescent (MIP-FL) probe has been synthesized by embedding glutathione-stabilized gold nanoclusters (GSH-AuNCs) and Fe3O4 nanoparticles (Fe3O4NPs) into silica composites. The Fe3O4NPs/AuNCs@MIPs are characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and UV?Vis absorption spectroscopy. The results show that the spherical Fe3O4NPs/AuNCs@MIPs contain a core-shell structure with GSH-AuNCs anchored on the surface of silica-protected Fe3O4NPs. As a fluorescence probe (excitation: 360?nm, emission: 615?nm), Fe3O4NPs/AuNCs@MIPs can selectively detect metronidazole (MNZ) among other nitroimidazoles (ronidazole, ornidazole, and tinidazole). During the detection, the fluorescence intensity of the MIP-FL probe drops gradually with increasing MNZ concentration. The sensitive linear range of the fluorescence probe is from 0 to 5 ?M, and the limit of detection is 4.2 nM. After the recognition sites interact with the template, the occurrence of charge transfer from the GSH-AuNCs to MNZ results in fluorescence quenching. Finally, a real sample test has been performed in spiked milk. Satisfactory recoveries spanning from 96% to 102% indicate that Fe3O4NPs/AuNCs@MIPs enable highly sensitive detection of MNZ based on fluorescence signal output, while the MIPs also have enrichment potential for the target from complex samples due to the magnetic properties.

Quenching of Salicylaldehyde-based Luminescence Probe via Dakin Reaction: Approach for Highly Selective Detection of Hydrogen Peroxide

Nai-Di Tan,Yaqing Yuan,Jian-Hang Yin,Na Xu 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.8

A novel assay for H2O2 based on luminescence quenching is developed from the Dakin reaction between deprotonated salicylaldehyde (D-SA) and H2O2. Under alkaline condition, the phenolic hydroxyl group of SA is deprotonated, exhibiting good luminescence emission ability (λex = 433 nm, λem = 508 nm). Luminescence of D-SA is quenched by H2O2 in a concentration-dependent manner. Good linearity is obtained with a regression coefficient of 0.9989 in the range of 0.3 ~ 150 μM and a detection limit (LOD) is 30 nM. In addition, D-SA luminescence probe shows good biocompatibility and low cytotoxicity to HeLa cells through MTT assay. The feasibility for in vitro applications is demonstrated through confocal laser scanning microscopy.

Triterpenoid saponins from Clinopodium chinense (Benth.) O. Kuntze and their biological activity

Yin-Di Zhu,Jing-Yi Hong,Feng-Da Bao,Na Xing,Ling-Tian Wang,Zhong-Hao Sun,Yun Luo,Hai Jiang,Xudong Xu,Nai-Liang Zhu,Hai-Feng Wu,Gui-Bo Sun,Jun-Shan Yang 대한약학회 2018 Archives of Pharmacal Research Vol.41 No.12

Four new ursane-type triterpenoid saponins, clinopoursaponins A–D (1–4), six new oleanane-type triterpenoid saponins, clinopodiside VII–XII (5–10), as well as eight known triterpene analogues (11–18), were isolated from the aerial parts of Clinopodium chinense (Benth.) O. Kuntze. The structures of the new compounds were determined based on extensive spectral analyses, including 1D (1H and 13C) and 2D NMR experiments (COSY, NOESY, HSQC, 2D TOCSY, HSQC-TOCSY and HMBC), HR-ESI-MS and chemical methods. Compounds 1–18 were evaluated for their protective effects against anoxia/reoxygenation-induced apoptosis in H9c2 cells and cytotoxicities against murine mammary carcinoma cell line 4T1. Compounds 8, 9 and 18 exhibited significant protective effects, while compound 1 exhibited cytotoxic activity with IC50 value of 7.4 μm compared to 7.6 μm for the positive control 10-hydroxycamptothecin.

Efficiency Optimization of Variable Iron Loss Resistance Asynchronous Motor Based on Grey Wolf Optimization Algorithm

Guo Zhen,Tong Di,Zhao Yan-cheng,Chen Shuang,Nai Ji-qiu,Ye Ming-hao 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1

Asynchronous motor is widely used in various industrial fields. When asynchronous motor works in case close to the rated load, it will run at maximum efficiency. However, most of the load is 50–100% of rated load and it will lead to the serious waste of energy. This paper proposes an efficiency optimization control strategy based on the grey wolf optimization algorithm to improve the operating efficiency of asynchronous motors at light loads. The motor loss model considering the change of iron loss is established and it makes the asynchronous motor model more accurate. The grey wolf optimization algorithm is used to find the optimized flux value. When the asynchronous motor operates at the optimal flux, the loss power of the motor is decreased and the operation efficiency improves effectively. The proposed method reduces the flux search time and improves the stability of the system. The simulation model is established and the simulation results are provided to verify the feasibility of the proposed control strategy achieving the global efficiency optimum of asynchronous motor.

Mg(OH)2/Graphene Nanocomposites Prepared by Cathodic Electrodeposition for the Adsorption of Congo Red

Xinzhong Deng,Yao-wu Wang,Jianping Peng,Kejia Liu,Nai-xiang Feng,Yuezhong Di 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.2

A facile cathodic electrodeposition process was developed to prepare Mg(OH)2/Graphene nanocomposites (MGN), which was used to remove Congo Red (CR), an anionic dye from aqueous solution. The morphology and phase structure were analyzed by transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Raman and X-ray photoelectron spectroscopy (XPS). The effects of experimental parameters, such as graphene content, adsorption time, initial concentrations of CR and pH values, on the adsorption capacity of CR were studied. The obtained MGN shows the good performance in CR, with an adsorption capacity of 1986.43 mg g-1. The equilibrium adsorption and kinetics data fit with Langmuir isotherm and the pseudo-second-order model, respectively. Thermodynamic data suggest that CR adsorption onto MGN is spontaneous (ΔG0 : –9.62 kJ mol-1 at 313 K, endothermic (ΔH0 : 36.261 kJ mol-1) and the degree of disorder increased (ΔS0 : 146.848 J moL-1 K-1) at the solidsolution interface. Moreover, the adsorption activation energy (Ea: 38.929 kJ mol-1) of CR evaluated from the Arrhenius equation illustrates that it is a physical process. This adsorbent exhibits efficient adsorption properties and high recycling efficiency, making it a promising adsorbent for removing anionic dyes.