Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published February 17, 2010 | Supplemental Material
Journal Article Open

Paramagnetic, Silicon Quantum Dots for Magnetic Resonance and Two-Photon Imaging of Macrophages

Abstract

Quantum dots (QDs) are an attractive platform for building multimodality imaging probes, but the toxicity for typical cadmium QDs limits enthusiasm for their clinical use. Nontoxic, silicon QDs are more promising but tend to require short-wavelength excitations which are subject to tissue scattering and autofluorescence artifacts. Herein, we report the synthesis of paramagnetic, manganese-doped, silicon QDs (Si_(Mn) QDs) and demonstrate that they are detectable by both MRI and near-infrared excited, two-photon imaging. The Si_(Mn) QDs are coated with dextran sulfate to target them to scavenger receptors on macrophages, a biomarker of vulnerable plaques. TEM images show that isolated QDs have an average core diameter of 4.3 ± 1.0 nm and the hydrodynamic diameters of coated nanoparticles range from 8.3 to 43 nm measured by dynamic light scattering (DLS). The Si_(Mn) QDs have an r_1 relaxivity of 25.50 ± 1.44 mM^(−1) s^(−1) and an r_2 relaxivity of 89.01 ± 3.26 mM^(−1) s^(−1 )(37 °C, 1.4 T). They emit strong fluorescence at 441 nm with a quantum yield of 8.1% in water. Cell studies show that the probes specifically accumulate in macrophages by a receptor-mediated process, are nontoxic to mammalian cells, and produce distinct contrast in both T_1-weighted magnetic resonance and single- or two-photon excitation fluorescence images. These QDs have promising diagnostic potential as high macrophage density is associated with atherosclerotic plaques vulnerable to rupture.

Additional Information

© 2010 American Chemical Society. Received November 2, 2009. Publication Date (Web): January 21, 2010. We acknowledge the National Institute of Health (HL081108-01, EB008576-01, and EB006192), a German Science Foundation (DFG) Postdoctoral Fellowship, and the NMR award of the University of California, Davis for support of this work. We thank Dr. Xiaobo Liu for help in two-photon imaging.

Attached Files

Supplemental Material - ja909303g_si_001.pdf

Files

ja909303g_si_001.pdf
Files (220.9 kB)
Name Size Download all
md5:437bed47757603470a88fd9bf1957cd4
220.9 kB Preview Download

Additional details

Created:
August 19, 2023
Modified:
October 20, 2023