Suppression of the reticuloendothelial system using λ-carrageenan to prolong the circulation of gold nanoparticles.

Aim: Gold nanoparticles are employed for imaging and treatment of surgically inaccessible tumors owing to their inherent optical absorption and ability to extravasate through intravenous distribution. These nanoparticles are cleared from the blood by the reticuloendothelial system (RES) as expected given their size.

Materials & Methods: This study demonstrates the effects of RES blockade through the intravenous administration of λ-carrageenan, resulting in a decrease in the median clearance rate from 18.9 (95% CrI: 15.9-22.6) to 11.2 (95% CrI: 8.8-13.9) μl/min and an increase in nanoparticle circulation half-life t(½)( = 264 ± 73 vs 160 ± 22 min; p < 0.01).

Results: This 59.3% decrease in clearance is greater than the 15% previously reported for liposomes [ 1 ].

Conclusion: The primary benefit of nontoxic RES blockade is to increase the circulation time, where traditional particle modification is ineffective or impractical.