Our group is investigating the use of ZnS-capped CdSe quantum dot (QD) bioconjugates combined with fluorescence
endoscopy for improved early cancer detection in the esophagus, colon and lung. A major challenge in using fluorescent
contrast agents in vivo is to extract the relevant signal from the tissue autofluorescence (AF). Our studies are aimed at
maximizing the QD signal to AF background ratio (SBR) to facilitate detection. This work quantitatively evaluates the
effect of the excitation wavelength on the SBR, using both experimental measurements and mathematical modeling.
Experimental SBR measurements were done by imaging QD solutions placed onto (surface) or embedded in (sub-surface)
ex vivo murine tissue samples (brain, kidney, liver, lung), using a polymethylmethacrylate (PMMA)
microchannel phantom. The results suggest that the maximum contrast is reached when the excitation wavelength is set
at 400±20 &mgr;m for the surface configuration. For the sub-surface configuration, the optimal excitation wavelength varies
with the tissue type and QD emission wavelengths. Our mathematical model, based on an approximation to the
diffusion equation, successfully predicts the optimal excitation wavelength for the surface configuration, but needs
further modifications to be accurate in the sub-surface configuration.
Biocompatible ZnS capped CdSe fluorescent semiconductor nanocrystals (quantum dots, QDs) exhibit great potential as imaging agents with biomedical and clinical relevance. However, little is known about the fate of the quantum dots <i>in vivo</i>, and the importance of chemical and physical composition that may influence their behavior <i>in vivo</i>. When the QDs are introduced <i>in vivo</i>, the first interactions with blood components will dictate their kinetic behavior <i>in vivo</i>. We present some preliminary results that demonstrate the interactions of the quantum dots with plasma proteins and that quantum dots can be trapped in fibrous networks.
The interface of targeting molecules that can recognize and identify specific biomolecules with highly luminescent semiconductor nanocrystals or quantum dots can lead to a novel and powerful new class of probes for studying biomolecules in real-time or for imaging and detecting diseases. We describe the rationale design of optical nanoprobes by using fluorescent semiconductor quantum dots with targeting molecules (TMs)-identified using phage display screening. Quantum dots are nanometer-sized particles with unique and tunable optical properties. They offer numerous optical advantages over traditional organic fluorophores in biological analysis and detection (e.g., photostability, continuous absorption profile).
Conference Committee Involvement (3)
Colloidal Quantum Dots for Biomedical Applications II
20 January 2007 | San Jose, California, United States
Colloidal Quantum Dots for Biomedical Applications
22 January 2006 | San Jose, California, United States