Sun Jong Lee

Synthesis and characterization of multifunctional Fe3O4/poly(fluorescein O-methacrylate) core/shell nanoparticles.

Multifunctional fluorescent and superparamagnetic Fe(3)O(4)/poly(fluorescein O-methacrylate) [Fe(3)O(4)/poly(FMA)] nanoparticles with core/shell structure were synthesized via surface-initiated polymerization. First, polymerizable double bonds were introduced onto the surface of Fe(3)O(4) nanoparticles via ligand exchange and a condensation reaction. A fluorescent monomer, FMA, was then polymerized to the double bonds at the surface via free-radical polymerization, leading to form a fluorescent polymer shell around the superparamagnetic Fe(3)O(4) core. The resultant Fe(3)O(4)/poly(FMA) nanoparticles were characterized by Fourier transform infrared, nuclear magnetic resonance, and X-ray diffraction spectroscopy to confirm the reactions. Transmission electron microscopy images showed that the Fe(3)O(4)/poly(FMA) nanoparticles have a spherical and monodisperse core/shell morphology. Photoluminescence spectroscopy and superconducting quantum interference device magnetometer analyses confirmed that the Fe(3)O(4)/poly(FMA) nanoparticles exhibited fluorescent and superparamagnetic properties, respectively. In addition, we demonstrated the potential bioimaging application of the Fe(3)O(4)/poly(FMA) nanoparticles by visualizing the cellular uptake of the nanoparticles into A549 lung cancer cells.

Luminescent gold–poly(thiophene) nanoaggregates prepared by one-step oxidative polymerization

We report the facile synthesis, formation mechanism, and photoluminescent (PL) properties of gold–poly(thiophene) (Au–PTh) nanoaggregates. They were prepared by one-step oxidative polymerization, in which Au3+ ion was utilized as an oxidizing agent for the polymerization of thiophene. Transmission electron microscopy (TEM) and high-resolution TEM (HR-TEM) analyses demonstrated that the ‘raspberry-like’ Au–PTh nanoaggregates consist of individual Au NPs covered by PTh and stabilized by Tween 80. For Au–PTh nanoaggregates, a clear red shift in the SP peak was observed in the UV absorption spectra as compared with pristine Au nanoparticles (NPs). This red shift of the SP band is a consequence of the location of π-conjugated PTh on the surface of Au NPs, resulted from a strong binding between sulfur atoms of PTh and the Au NPs (sulfur–gold interaction). The strong interaction between the gold and sulfur atoms of PTh in the Au–PTh nanoaggregates was observed by X-ray photoelectron spectroscopy (XPS) analysis. The SP effect contributes to the PL intensity enhancement of the Au–PTh nanoaggregates and was confirmed by confocal laser scanning microscopy (CLSM).

Tunable fluorescent poly(styrene-co-methacrylic acid)/Au-Aphen hybrid nanoparticles via surface immobilization

Tunable fluorescent poly(styrene-co-methacrylic acid) [poly(St-co-MAA)]/Au-Aphen hybrid nanoparticles were fabricated by immobilizing the 5-amino-1,10-phenanthroline functionalized gold nanoparticles (Au-Aphen) on the surface of copolymer nanoparticles in aqueous solution. Aphen-Au cationic complex was absorbed on the surface of poly(St-co-MAA) nanoparticles by using electrostatic interactions and metalized by a reduction process. Thus, the functionalized metal nanoparticles can be immobilized onto the surface of the copolymer nanoparticles to significantly modify their optical properties. The structure of the hybrid nanoparticles was confirmed by infrared spectroscopy, scanning electron microscopy, X-ray diffraction, UV-vis spectrophotometery and spectrofluorophotometery studies. These hybrid nanoparticles exhibited fluorescence properties with enhanced photoluminescence quantum yield compared to the gold clusters. Furthermore, the fluorescent emission wavelength of hybrid nanoparticles can be tuned precisely by changing the amount of Aphen functionalized gold nanoparticles on the surface of poly(St-co-MAA) nanoparticles. PL spectra of hybrid nanoparticles showed a red-shift with increasing the amount of functionalized gold on the poly(St-co-MAA) nanoparticles surface in a water medium.

Synthesis and properties of phase change material-polypyrrole core-shell nanocapsules via Fe3+-oxidative miniemulsion polymerization

Abstract