posted on 2023-01-11, 13:39authored byCaleb
A. Cox, Ashley N. Ogorek, Jean Paul Habumugisha, Jeffrey D. Martell
Polymerization catalysts that activate in response to
specific
chemical triggers offer spatial and temporal control over polymer
synthesis, facilitating the development of responsive materials and
custom polymer coatings. However, existing catalysts switch their
activity through mechanisms that are not generalizable to chemically
diverse stimuli. To approach the level of control exhibited in biological
polymer synthesis, switchable polymerization catalysts need to be
configurable for activation in response to diverse chemical stimuli.
Here, we combine synthetic photocatalysts with conformation-switching
DNA aptamers to create polymerization catalysts that respond to diverse
chemical stimuli. We use the secondary structure of DNA to bring a
photocatalyst and quencher dye into proximity, turning off photocatalysis.
The DNA structure can be precisely designed to change conformation
in response to a molecular trigger, moving the photocatalyst far from
the quencher and activating photocatalysis. We show these photocatalysts
can initiate free-radical polymerization to form bulk hydrogels in
response to complementary DNA, a metal ion (Zn2+), or small
molecules (glucose and hydrocortisone). We demonstrate the biocompatibility
of these switchable photocatalysts by triggering their activation
on the surface of yeast cells. Finally, we perform reversible-deactivation
radical polymerization through photoinduced electron/energy transfer
reversible addition−fragmentation chain-transfer in a dual-stimulus
manner, in which catalytic activity is regulated reversibly by photoirradiation
and the conformational state of the DNA catalyst. These results demonstrate
that DNA conformational changes triggered by chemically diverse stimuli
can regulate the activity of radical polymerization photocatalysts.
This platform offers new capabilities in spatially and temporally
controlled polymer synthesis, with potential applications in diagnostics,
sensing, and environmentally responsive materials.