Liposome Encapsulation of Fluorescent Nanoparticles: Quantum Dots and Silica Nanoparticles
C.-S. Chen, J. Yao and R.A. Durst
Cornell University, US
liposome, nanoencapsulation, quantum dot, silica nanoparticle
Quantum dots (QDs) and silica nanoparticles (SNs) are new classes of fluorescent probes that overcome the limitations encountered by organic fluorophores in bioassay and biological imaging applications. We encapsulated QDs and SNs into liposomes by the reverse-phase evaporation method. Nanoparticle-loaded liposomes were separated from unencapsulated nanoparticles by size exclusion chromatography and their characteristics were investigated. Dual-color, two-photon fluorescence correlation spectroscopy was used to measure the number of nanoparticles inside each liposome. Results indicated that nanoparticle-loaded liposomes were formed and separated from unencapsulated nanoparticles by using Sepharose gel. As expected, fluorescence self-quenching of nanoparticles inside liposomes was not observed. When a 0.8 mM solution of 50 nm QDs was used for liposome preparation, each liposome encapsulated an average of three QDs. However, we could not measure the number of SNs inside each liposome due to the spectral overlap between the SNs and nitrobenzoxadiazol-liposomes. Our work showed that both QDs and SNs were encapsulated into liposomes and it provided a methodology to measure the number of nanoparticles inside each liposome with fluorescence correlation spectroscopy.
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Nanotech 2005 Conference Program Abstract