Nano

Talanta 72 (2007) 1693–1697

Multifunctional nanoparticles possessing magnetic, long-lived fluorescence and bio-affinity properties for time-resolved fluorescence cell imaging
Jing Wu a , Zhiqiang Ye a , Guilan Wang b , Jingli Yuan a,b,∗
a

Department of Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, PR China b State Key Laboratory ofFine Chemicals, Department of Chemistry, Dalian University of Technology, Dalian 116012, PR China Received 20 November 2006; received in revised form 3 March 2007; accepted 12 March 2007 Available online 20 March 2007

Abstract Multifunctional nanoparticles possessing magnetic, long-lived fluorescence and bio-affinity properties have been prepared by copolymerization of a conjugate of(3-aminopropyl)triethoxysilane bound to a fluorescent Eu3+ complex, 4,4 -bis(1 ,1 ,1 -trifluoro- 2 ,4 -butanedion-4 -yl)chlorosulfoo-terphenyl-Eu3+ (APS-BTBCT-Eu3+ ), free (3-aminopropyl)triethoxysilane (APS) and tetraethyl orthosilicate (TEOS) in the presence of poly(vinylpyrrolidone) (PVP) stabilized magnetic Fe3 O4 nanoparticles (∼10 nm) with aqueous ammonia in ethanol. The nanoparticles were characterized bytransmission electron microscopy (TEM), spectrofluorometry and vibrating sample magnetometry methods. The direct-introduced amino groups on the nanoparticle’s surface by using free APS in nanoparticle preparation facilitated the surface modification and bioconjugation of the nanoparticles. The nanoparticle-labeled transferrin was prepared and used for staining the cultured Hela cells. Atime-resolved fluorescence imaging technique that can fully eliminate the fast-decaying background noises was developed and used for the fluorescence imaging detection of the cells. A distinct image with the high ratio of signal to noise (S/N) was obtained. © 2007 Elsevier B.V. All rights reserved.
Keywords: Europium; Biolabeling; Cell imaging; Nanoparticle; Time-resolved fluorescence

1. IntroductionMagnetic ferrite nanoparticles have been widely used in analytical biochemistry, medicine and biotechnology recently [1–8]. These super-paramagnetic nanoparticles can be attracted by a magnetic field but retain no residual magnetism after the field is removed. Therefore, suspended super-paramagnetic nanoparticles tagged to the biomaterials of interest can be easily separated from a matrix by using amagnetic field without agglomeration after removal of the field. Transmission electron microscopy and magnetic resonance imaging have been used to study magnetic nanoparticles incorporated into cells. However, they are not convenient for in situ monitoring, thus a sensitive and simple technique for in situ mon-

∗ Corresponding author at: Department of Analytical Chemistry, Dalian Institute of ChemicalPhysics, Chinese Academy of Sciences, Dalian 116023, PR China. Tel.: +86 411 84379660; fax: +86 411 84379660. E-mail address: jingliyuan@yahoo.com.cn (J. Yuan).

itoring of the nanoparticles in living cells is desirable. In the past few years, fluorescence labeling and imaging techniques for living cells using fluorescent nanoparticles, such as semiconductor nanoparticles (quantum dots) [9,10] andsilica-based fluorescent nanoparticles [11,12], have been developed. Compared to conventional organic fluorescence probes, advantages of the nanometer-sized fluorescence probes mainly include their higher photostability and stronger fluorescence. The main problem in cell imaging using the fluorescent nanoprobes is that the fluorescence signal is easily affected by the background noises caused by thecells, matrix and the non-specific scattering lights. The high signal to noise (S/N) ratio is difficult to be obtained. Time-resolved fluorescence bioassays using lanthanide complexes as probes have been widely used for highly sensitive detections of various biomolecules [13–15]. This technique is also a very useful tool for fluorescence bioimaging detections [16,17] since the fast-decaying background...