(225c) Microreactors for Click Chemistry Based Conjugation

                Click chemistry has been
used in a myriad of applications across several scientific fields, including
organic chemistry, medicinal chemistry, and chemical biology.  Specifically, the Cu(I)-catalyzed
azide-alkyne cycloaddition
(CuAAC) is used extensively in nuclear medicine for
the synthesis of radiotracers utilized in molecular imaging procedures.  CuAAC offers a chemoselective method of conjugating a bifunctional
chelator to a targeting biomolecule.  This copper catalyzed reaction's chemoselective nature provides an assimilation system that
can easily be adapted for other imaging modalities or biomolecules.

Despite the high yields achievable
by a CuAAC reaction, it's
use is plagued by limitations inherent to conventional techniques for chemical
synthesis.  These techniques require
large volumes of expensive reagents, and possess inadequate flexibility to
optimize the procedure.  Microfluidics provides
a method for efficient, rapid chemical synthesis due to enhanced heat and mass
transfer, and also requires low reagent volumes.  Working on the microscale
allows a high-throughput method for the synthesis and functional study of a
library of cancer imaging agents.  In
conjunction with click chemistry, microfluidic platforms afford an efficient,
rapid, versatile system for conjugation.

This study specifically focused on
the impact of heterogeneous catalysis on CuAAC in a
microreactor.  Experiments included the
effects of flow rates and length of reactor on product yields and synthesis
time.  The conjugation of azide-fluor 568 to propargylamine
was used as a test reaction to confirm the benefits of using heterogeneous
click chemistry catalysis on chip.