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The aim of this work was to develop a simple and rapid analytical method for the simultaneous determination of a wide range of drug residues in milk by UHPLC-MS/MS. A total of 25 typical veterinary drugs investigated belong to six families including β-lactams, quinolones, β-agonists, phenicols, glucocorticoids and nitrofurans. The samples were extracted by acetonitrile and defatted with n-hexane twice. Electrospray ionization and positive/negative polarity switching were utilized for the analysis of 25 veterinary drugs in a single chromatographic run. The linearity, recovery, precision and matrix effects of the method were fully validated. The intra- and inter-precision were in the range of 1.7-11.1% and 2.5-10.4%, respectively. The average recoveries ranged from 65.9% to 123.5% with RSD less than 10.8% at three concentration levels. The proposed method was demonstrated to be simple, economical and reliable for the fast monitoring of these drug residues in milk samples.

Microthrix parvicella (M. parvicella) is a filamentous bacterium that induces bulking in activated sludge. Here, we used the affinity of long-chain fatty acids (LCFA) for M. parvicella to create a novel fluorescent probe of carbazole modified by LCFA. The structure was characterized by 1H NMR spectroscopy and mass spectrometry. The spectral properties, photostability, and hydrophobic properties of the probe were also characterized. Fluorescent-labeling results showed that it can label M. parvicella in situ and could be biodegraded via metabolism. The stable docking mode of carbazole probes with different fatty acid chains and lipases was also docked by the density functional tight-binding (DFTB) method.

A novel near-infrared (NIR) ratiometric colorimetric ICT-based fluorescence probe for hydrazine has been synthesized and characterized. The probe DCM-LX selectively distinguished hydrazine with other analyses with a wide pH range. Once hydrazine is added to the solution of probe DCM-LX, the color of solution changed to orange from yellow immediately. It means probe can be used for “naked-eye” detection of hydrazine. DCM-LX exhibits high selectivity and excellent sensitivity towards hydrazine with detection limit as low as 7.71 nM. Furthermore, DCM-LX was successfully applied in living cellular imaging with low toxicity and hydrazine detection in H 2 O sample.

Xueling Ren, Jing Lin, Xuefang Wang, Xiao Liu, Erjuan Meng, Rui Zhang, Yanxiao Sang, Zhenzhong Zhang Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, People’s Republic of China Abstract: The efficacy of RNA interference (RNAi)-based cancer gene therapy is limited by its unexpected side effects, thus necessitating a strategy to precisely trigger conditional gene knockdown. In this study, we engineered a novel photoactivatable RNAi system, named as polyetherimide-modified single-wall carbon nanotube (PEI-SWNT)/pHSP-shT, that enables optogenetic control of targeted gene suppression in tumor cells. PEI-SWNT/pHSP-shT comprises a stimulus-responsive nanocarrier (PEI-SWNT), and an Hsp70B'-promoter-driven RNAi vector (pHSP-shT). In response to near-infrared (NIR) light irradiation, heating of PEI-SWNT in breast MCF-7 cells triggered gene knockdown targeting human telomerase reverse transcriptase through RNAi, with the gene-knockdown activity capable of being switched off by extinguishing the NIR. Furthermore, we demonstrated that the photoactivatable RNAi system exhibited higher antitumor activity by combining gene therapy and photothermal therapy, both in vitro and in vivo. Optogenetic control of RNAi based on an NIR-activated nanocarrier will potentially facilitate improved understanding of molecular-targeted gene therapy in human malignant tumors. Keywords: near-infrared light response, SWNT, RNAi, Hsp70B' promoter

A two-photon reversible fluorescent probe L1 was designed and synthesized. The fluorescence intensity of the probe solution was strong, while the fluorescence of the solution was obviously quenched and the color of the solution was changed after the addition of hypochlorous acid, indicating this is “naked-eye sensor” for the detection of HClO. The probe showed great selectivity for hypochlorous acid over other reactive oxygen species (ROS) and anions. Fluorescence titration experiments showed that the probe has a low detection limit of 0.674 μM. Because of a morpholine group introduced to the naphathalimide framework, probe L1 was successfully applied to detect intracellular HClO in lysosome.

Due to the difference in the physical and mechanical properties between the optical fiber, protective layer, adhesive layer, and the host material, the strains measured by a fiber Bragg grating (FBG) sensor may not be the actual strains of the host material, which impedes the reliable applications of FBG sensors. To overcome this problem, in this paper, the strain transfer formula was derived by using elastic analysis, the shear-lag method, and several reasonable assumptions taking into account temperature variations and nonaxial stresses, which was an improvement to an existing study (Li, H. N., Zhou, G. D., Ren, L., and Li, D. S., “Strain Transfer Analysis of Embedded Fiber Bragg Grating Sensor Under Nonaxial Stress,” Optic. Eng., Vol. 46, No. 5, 2007, 054402). The analytical results were validated by simulating the behavior of a bare optical fiber through finite element analysis. The data enabled the identification of the parameters that influence the strain transfer from the host material to the embedded FBG sensors and the impact of the temperature variation and sensor alignment angle on the measurement accuracy. This work provided additional knowledge for the improvement of the existing strain transfer theory of FBG sensors in order to achieve a more accurate strain measurement with this sensing technology.