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Am J Nucl Med Mol Imaging 2012;2(2):122-135.
Original Article
Synthesis and characterization of intrinsically radio-labeled quantum dots for
bimodal detection
Minghao Sun, David Hoffman, Gobalakrishnan Sundaresan, Likun Yang, Narottam Lamichhane, Jamal Zweit
Center for Molecular Imaging, Department of Radiology, Virginia Commonwealth University, Richmond, Virginia, 23298, USA
Received January 18, 2012; accepted February 1, 2012; Epub March 28, 2012; Published April 15, 2012
Abstract: A novel approach was developed to synthesize radioactive quantum dots (r-QDs) thereby enabling both optical and
radionuclide signals to be detected from the same intrinsic bimodal probe. This proof-of-concept is exemplified by the incorporation
of the radionuclide 109Cadmium into the core/shell of the nanoparticle. Green and near infrared (NIR) emission intrinsic r-QDs were
synthesized and characterized. Zwitterionic and Poly-polyethlene glycol (PEGylated) ligands were synthesized and used to coat
r-QDs. Zwitterionic NIR r-QDs (quantum yield = 11%) and PEGylated NIR r-QDs (quantum yield = 14%) with an average size of 13.8
nm and 16.8 nm were obtained respectively. The biodistribution of NIR zwitterionic and PEGylated r-QDs in nude mice was
investigated and zwitterionic r-QDs showed longer blood circulation (t1/2 = 21.4±1.1 hrs) than their PEGylated counterparts (t1/2 =
6.4±0.5 min). Both zwitterionic and PEGylated r-QDs exhibited progressive accumulation in the liver and spleen, but the magnitude of
the accumulation (%ID/g) was about 3-6 fold higher with the PEGylated r-QDs at all the time points. The results demonstrated the
feasibility of r-QDs synthesis in quantitative yield and retention of fluorescence following incorporation of radioactivity into the
core/shell of the nanoparticle. The gamma signal from the same fluorescent elemental material enabled quantitative and robust
pharmacokinetic measurements and how these changed depending on the type of coating ligands used. This strategy for
intrinsically radio-labeling the QDs is currently being implemented in our laboratory for the incorporation of other radiometals.
(ajnmmi1201001).
Keywords: Quantum dots, intrinsically radio-labeled, biodistribution, molecular imaging, bimodal detection
Full text PDF
Address all correspondence to:
Dr. Jamal Zweit
Center for Molecular Imaging, Department of Radiology
1101 East Marshall Street, 8-022, Virginia Commonwealth University
Richmond, VA, 23298, USA.
E-mail: jzweit@vcu.edu
Original Article
Synthesis and characterization of intrinsically radio-labeled quantum dots for
bimodal detection
Minghao Sun, David Hoffman, Gobalakrishnan Sundaresan, Likun Yang, Narottam Lamichhane, Jamal Zweit
Center for Molecular Imaging, Department of Radiology, Virginia Commonwealth University, Richmond, Virginia, 23298, USA
Received January 18, 2012; accepted February 1, 2012; Epub March 28, 2012; Published April 15, 2012
Abstract: A novel approach was developed to synthesize radioactive quantum dots (r-QDs) thereby enabling both optical and
radionuclide signals to be detected from the same intrinsic bimodal probe. This proof-of-concept is exemplified by the incorporation
of the radionuclide 109Cadmium into the core/shell of the nanoparticle. Green and near infrared (NIR) emission intrinsic r-QDs were
synthesized and characterized. Zwitterionic and Poly-polyethlene glycol (PEGylated) ligands were synthesized and used to coat
r-QDs. Zwitterionic NIR r-QDs (quantum yield = 11%) and PEGylated NIR r-QDs (quantum yield = 14%) with an average size of 13.8
nm and 16.8 nm were obtained respectively. The biodistribution of NIR zwitterionic and PEGylated r-QDs in nude mice was
investigated and zwitterionic r-QDs showed longer blood circulation (t1/2 = 21.4±1.1 hrs) than their PEGylated counterparts (t1/2 =
6.4±0.5 min). Both zwitterionic and PEGylated r-QDs exhibited progressive accumulation in the liver and spleen, but the magnitude of
the accumulation (%ID/g) was about 3-6 fold higher with the PEGylated r-QDs at all the time points. The results demonstrated the
feasibility of r-QDs synthesis in quantitative yield and retention of fluorescence following incorporation of radioactivity into the
core/shell of the nanoparticle. The gamma signal from the same fluorescent elemental material enabled quantitative and robust
pharmacokinetic measurements and how these changed depending on the type of coating ligands used. This strategy for
intrinsically radio-labeling the QDs is currently being implemented in our laboratory for the incorporation of other radiometals.
(ajnmmi1201001).
Keywords: Quantum dots, intrinsically radio-labeled, biodistribution, molecular imaging, bimodal detection
Full text PDF
Address all correspondence to:
Dr. Jamal Zweit
Center for Molecular Imaging, Department of Radiology
1101 East Marshall Street, 8-022, Virginia Commonwealth University
Richmond, VA, 23298, USA.
E-mail: jzweit@vcu.edu
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