Intracellular protein delivery shows great promise in the treatment of various diseases. However, therapeutic applications of this method are limited by its low delivery efficiency and poor targeting ability. As one of most important drug delivery cargoes, Fe₃O₄ nanoparticles (nFe₃O₄) have attracted much attention for both therapeutic and diagnostic applications, especially for targeting drug delivery. To use nFe₃O₄ for protein delivery, a simple but effective modification of nFe₃O₄ is critical to attach proteins on its surface. In this work, by designing and synthesizing cationic poly(2-(dimethylamino)ethyl methacrylate) (PDMA)-grafted nFe₃O₄ via in situ atom transfer radical polymerization (ATRP), we demonstrate a simple solution to improve interactions between nFe₃O₄ and proteins. With the grafted PDMA on the surface, nFe₃O₄ exhibits not only significant enhancement in dispersibility and stability in aqueous phase, but also an excellent capability to attach negative-charged proteins. Moreover, with the assistance of external magnetic field, PDMA-grafted nFe₃O₄ can be used as a targetable vector to deliver proteins into specific cells. This work provides a novel platform based on cationic magnetite nanoparticles that can deliver therapeutic proteins into specific sites for the treatment of various diseases. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40260.

ZnO nanocrystals (NCs), potential candidates for photoluminescent applications, have attracted increasing attention recently because of their good biocompatibility, low cost, and convenient synthesis. However, their stability and fluorescent quenching, particularly in the aqueous phase, still hampers their use in biological applications. We report herein the synthesis of ZnO NCs modified by amphiphilic methoxy poly(ethylene glycol)-grafted poly(styrene-alt-maleic anhydride) (SMA-g-MPEG) copolymer based on the sol–gel method. We demonstrated a simple solution to address those challenges. Compared with unmodified ZnO NCs, SMA-g-MPEG modified ZnO NCs exhibited a significantly improvement in the stability and photoluminescent properties in the aqueous phase over current unmodified ones. This simple synthesis provides a novel platform for the preparation of ZnO NCs for biological applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Fluorescent microspheres have great potential for use as probes in biological diagnostics. In this context, poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV), a conjugated polymer which has high quantum yield, controllable emitting wavelength and facile processing in manufacture, was used as a fluorescent material for the preparation of polystyrene (PS)/MEH-PPV fluorescent microspheres via miniemulsion polymerization. We demonstrate that the emitting wavelength of the PS/MEH-PPV fluorescent microspheres can be regulated by changing the amount of azobisisobutyronitrile initiator in the polymerization process. Using acrylic acid comonomer, poly[styrene-co-(acrylic acid)]/MEH-PPV fluorescent microspheres with functional carboxyl groups were also prepared. All the microspheres were characterized using transmission electron microscopy, scanning electron microscopy, fluorescence microscopy and fluorescence spectrophotometry. The functional carboxyl groups were characterized using Fourier transform infrared spectroscopy. This work provides a novel platform for the preparation of conjugated polymer fluorescent microspheres for biological applications. © 2012 Society of Chemical Industry