Multifunctional nanoparticles possessing magnetic, long-lived fluorescence and bio-affinity properties for time-resolved fluorescence cell imaging.

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 Eu(3+) complex, 4,4'-bis(1'',1'',1''-trifluoro- 2'',4''-butanedion-4''-yl)chlorosulfo-o-terphenyl-Eu(3+) (APS-BTBCT-Eu(3+)), free (3-aminopropyl)triethoxysilane (APS) and tetraethyl orthosilicate (TEOS) in the presence of poly(vinylpyrrolidone) (PVP) stabilized magnetic Fe(3)O(4) nanoparticles (approximately 10 nm) with aqueous ammonia in ethanol. The nanoparticles were characterized by transmission 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. A time-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.