2 research outputs found
Turning an Aptamer into a Light-Switch Probe with a Single Bioconjugation
We
describe a method for transforming a structure-switching aptamer
into a luminescent light-switch probe via a single conjugation. The
methodology is demonstrated using a known aptamer for Hg<sup>2+</sup> as a case study. This approach utilizes a lanthanide-based metallointercalator,
Eu-DOTA-Phen, whose luminescence is quenched almost entirely and selectively
by purines, but not at all by pyrimidines. This complex, therefore,
does not luminesce while intercalated in dsDNA, but it is bright red
when conjugated to a ssDNA that is terminated by several pyrimidines.
In its design, the light-switch probe incorporates a structure-switching
aptamer partially hybridized to its complementary strand. The lanthanide
complex is conjugated to either strand via a stable amide bond. Binding
of the analyte by the structure-switching aptamer releases the complementary
strand. This release precludes intercalation of the intercalator in
dsDNA, which switches on its luminescence. The resulting probe turns
on 21-fold upon binding to its analyte. Moreover, the structure switching
aptamer is highly selective, and the long luminescence lifetime of
the probe readily enables time-gating experiments for removal of the
background autofluorescence of the sample