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MMP-2-responsive fluorescent nanoprobes for enhanced selectivity of tumor cell uptake and imaging
Sun, Lu,Xie, Shuping,Ji, Xiuru,Zhang, Jingming,Wang, Dongmei,Lee, Seung Jin,Lee, Hyukjin,He, Huining,Yang, Victor C. The Royal Society of Chemistry 2018 Biomaterials Science Vol.6 No.10
<P>It is difficult to develop highly selective substrate-based fluorescent nanoprobes for specific matrix metalloproteinases (MMPs) due to overlapping substrate specificities among the family of MMP enzymes. To resolve this issue, we have developed novel fluorescent nanoprobes that are highly selective for soluble MMP-2. Herein, MMP-2-responsive nanoprobes were prepared by immobilizing fluorescent fusion proteins on nickel ferrite nanoparticles <I>via</I> the His-tag nickel chelation mechanism. The fusion protein consisted of a fluorescent mCherry protein with a cell penetrating peptide (CPP) moiety. An MMP-2 cleavage site was also introduced within the fusion protein, which was directly linked to the nickel ferrite nanoparticles. The selectivity of nanoprobes was modulated by hiding the cleavage site of MMP-2 substrates deeply inside the system, which could result in strong steric hindrance between the nanoprobes and MMPs, especially for membrane-tethered MMPs such as MMP-14. A cell-based assay demonstrated that the nanoprobes could only be activated by tumor cells secreting soluble MMP-2, but not membrane-tethered MMP-14. To further evaluate the contribution of the steric hindrance effect on the nanoprobes, a truncated recombinant MMP-14 was employed to confer their cleavage activity as compared to native membrane-tethered MMP-14. Furthermore, a designed probe with a diminished steric hindrance effect was proved to be activated by membrane-tethered type MMP-14. The results indicated that the design of fluorescent nanoprobes employing the steric hindrance effect can greatly enhance the selectivity of MMP-responsive nanoprobes realizing the specific detection of soluble MMP-2 in a tumor microenvironment. We believe that highly selective MMP-2-responsive fluorescent nanoprobes have broad impacts on biomedical applications including molecular imaging and labeling for tumor detection.</P>
Study on Electrical Aging Characteristics of Fiber Sheath Materials in Power Transformer Oil
Sun Lu,Fan Xiaozhou,Jiang Shuo,Wang Bowen,Liu Yunpeng,Gao Shuguo,Meng Lingming 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.1
Optical fiber has great potential in the development of online monitoring for trans-formers. In this paper, the electrical aging test of fiber sheath material based on a gradual voltage-rising method was performed and the influence of thermal aging on electrical aging was determined. Compared to the oil-paper insulation performance of traditional transformers, it was found that ethylene tetrafluoroethylene(ETFE), polytetrafluoroethylene(PTFE) and Polyamide 12 (PA 12) were better than oil-paper. Statistical analysis of the ETFE material and oil-paper test data was conducted using double-parameter Weibull distribution. The inverse power and exponential functions were used to fit the experimental data and voltage tolerance coefficients of the ETFE material were obtained. Experimental results show the parameters of the ETFE model in the inverse power function and exponential function model are better than those of the oil paper insulation, and the sheathed fiber is ETFE that can be stably operated in the transformer.