Joint Centers of Excellence Program

Metal chelating crosslinkers form nanogels with high chelation stability

26 Sep 2013

We present a series of hydrogel nanoparticles (nanogels) incorporating either acyclic or cyclic gadolinium chelates as crosslinkers. These polyacrylamide-based nanogels (diameter 50 to 85 nm) are contrast agents with enhanced relaxivities (up to 6-fold greater than DotaremĀ®), because the nanogel structure slows the chelator's tumbling frequency and allows fast water exchange. Importantly, these nanogels also stabilize Gd3+ within the chelator thermodynamically and kinetically against metal displacement through transmetallation, which should reduce toxicity associated with release of free Gd3+. This chelation stability suggests that the chelate crosslinker strategy may prove useful for other applications of metal-chelating nanoparticles in medicine, including other imaging modalities and radiotherapy.