Human apurinic/apyrimidinic endonuclease/redox effector factor 1 (APE1) is an essential DNA repair protein. Herein, we demonstrate that avidin-oriented abasic site-containing DNA strands (AP-DNA) on the surface of silica coated magnetic nanoparticles (SiMNP) can selectively respond to APE1 while resist the digestion by other nucleases. Mechanism studies have revealed that avidin may serve as an organizer protein and recruit APE1 to the DNA substrates on the nanoparticles via strong and specific interactions. Taking advantage of this newly disclosed property, we for the first time successfully displayed the intracellular activities of APE1 in living cells by fluorescence imaging. The avidin organized AP-DNA-SiMNP assembly holds great potential for enzyme-mediated release of drugs inside tumor cells which often contain higher levels of APE1 than normal cells.

We demonstrate the successful construction of fluorescently labeled magnetic antibody-like nanoparticles (ANPs) via a facile one-step surface-initiated in situ molecular imprinting approach over silica coated magnetite (Fe3O4@SiO2) core-shell nanocomposites. The as-prepared ANPs had a highly compact structure with an overall size of 83 ± 5 nm in diameter and showed excellent aqueous dispersion stability. With the predetermined high specificity to the target protein and high biocompatibility, the ANPs enabled rapid, efficient, selective and optically trackable sequestration of target proteins within living cells. This work represents the first example of fully artificially engineered multifunctional ANPs for the intracellular protein-sequestration without disruption of the cells. The established approach may be further extended to generate ANPs for various proteins of interest and provide useful tools for related biological research and biomedical applications.

In this study, a novel phosphorus-containing ionic monomer, named sodium salt of 10H-phenoxaphosphine-2,8-dicarboxylic acid,10-hydroxy-,2,8-dihydroxyethyl ester,10-oxide (DHPPO-Na), was synthesized, characterized, and then copolymerized to prepare poly(ethylene terephthalate)based ionomers. The chemical structure of the resulting ionomers was confirmed by 1 H, 13 C, and 31 P NMR spectroscopy. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to investigate the thermal properties of the ionomers. Compared with that of neat PET, the initial decomposition temperature of PETIs decreased in a nitrogen atmosphere while it increased in air. The crystallinity of PETIs was enhanced firstly and then destroyed with the ionic group increase. The limiting oxygen index (LOI) test and cone calorimeter were used to characterize the flame-retardant properties of the ionomers. The results showed that the introduction of DHPPO-Na could endow an expected flame-retardant performance, meanwhile it considerably restricted the melt-dripping behavior and suppressed the smoke release. The rheology test confirmed that the ionic groups increased the melt viscosity via ionic aggregation during heating, which was a benefit for the flame-retardant property of the copolyester.