John William Harder

Pharmacokinetics and biodistribution of near-infrared fluorescence polymeric nanoparticles

There has been increased interest in the use of polymeric nanoparticles as carriers for near-infrared fluorescence (NIRF) dyes for cancer diagnosis. However, efficient delivery of nanoparticles to the tumors after systemic administration is limited by various biobarriers. In this study, we investigated the pharmacokinetics, biodistribution, and tumor uptake of sub-nanometer sized polymeric nanoparticles (<100 nm in diameter) coated with polyethylene glycol in tumor-bearing mice. To facilitate our studies, these particles were labeled with gamma emitter indium-111. We found that two NIRF nanoparticles having the same size (approximately 20 nm) and chemical composition but different structures (i.e., hydrogel versus core-shell nanolatex), or the same core-shell nanolatex particles with different sizes (20, 30, and 60 nm), had different blood circulation times, biodistribution, and tumor uptake. Interestingly, the tumor uptake of the nanolatex particles correlated well with their blood residence times (R(2) = 0.95), but similar correlations were not found between nanogel and nanolatex particles (R(2) = 0.05). These results suggest that both the blood circulation time and the extent of hydration of the nanoparticles play an important role in the tumor uptake of nanoparticles. Prolonged blood circulation of these NIRF nanoparticles allowed clear visualization of tumors with gamma-scintigraphy and optical imaging after intravenous administration. A better understanding with regard to how the characteristics of nanoparticles influence their in vivo behavior is an important step towards designing NIRF nanoparticles suitable for molecular imaging applications and for efficient tumor delivery.

Increased sensitivity in antigen detection with fluorescent latex nanosphere-IgG antibody conjugates.

IgG antibodies were conjugated to Kodak X-Sight nanospheres to develop fluorescent-labeled antibodies using two different synthetic routes: one involving the DTT reduction method, and the other involving Trauts Reagent modification method. These two methods result in different conjugation efficiencies and different performances in antigen detection. Western blotting shows that the nanosphere-IgG antibody conjugates synthesized using the DTT reduction method are more immunospecific than the conjugates synthesized using Trauts Reagent modification method. In addition, the conjugates synthesized using DTT reduction also show higher antigen detection sensitivity than other commercially available fluorescent-IgG antibody conjugates, including Alexa Fluor, Qdot, and CyDye conjugates.