Biomedical Engineering Reference
In-Depth Information
6.2
Implications of Binding Affinity Studies on Component
Pair Selection
Through these experiments, a selective glucose competition assay was established
based on the binding affinities of DBAs for glucose and for an iDIOL surface.
Additionally, our studies confirmed that candidate DBA:iDIOL pairs can be suc-
cessfully screened for glucose sensitivity and selectivity. We have demonstrated
that it is possible to use Keq values to compare the binding affinities of a DBA for
glucose and of the same DBA for an iDIOL. This enabled us to qualitatively predict
the glucose-competitive response of each DBA:iDIOL pair and to select candidate
pairs that will generate reproducible glucose response curves with optimal sensitiv-
ity and selectivity. Intuitively, it can be assumed that component pairs that fall on
either extreme of the Keq interaction graph will generate undesirable glucose
response curves. On one end of the DBA:iDIOL affinity spectrum, the DBA
binds too strongly to the iDIOL and glucose cannot effectively compete. On the
other end of the affinity spectrum, the DBA binds too weakly to the iDIOL, which
will not provide a useful dynamic range. With the capability of predicting glucose
response curves based on the location of a Keq data interaction point, it was
possible for us to quickly and efficiently eliminate component pair combinations
that would be expected to perform in subsequent studies with low sensitivity and
selectivity. Much to our advantage, this screening approach drastically limits the
number of experiments that are required to select the best DBA:iDIOL combina-
tion, reducing time and cost investments. The results discussed above establish the
validity of the Keq data interaction model for selection of candidate DBA:iDIOL
pairs. The diversity of responses generated by each DBA:glucose:iDIOL system
within our library ensures that we will be able to select DBA:iDIOL pairs with the
appropriate physical and chemical properties necessary for analyzing glucose
concentrations within the sensitivity and selectivity parameters required by the
final device.
7 Concluding Remarks
We have designed and demonstrated a sensing system based on a DBA signaling
component and immobilized saccharide mimic (iDIOL). Our materials ultimately
do not require a fluorescent dye molecule to signal glucose concentration through
DBA:glucose:iDIOL competition, as the device will function through a mass-
sensitive signal transduction interface. In addition, the system components were
synthesized with favorable aqueous solubility and stability characteristics. Each
component was designed to include optimal structural motifs for the most favorable
glucose sensitivity and selectivity. Faced with the challenge of sensing a range of
physiologically relevant glucose concentrations in a complex matrix of potentially
competing analytes, we developed a competitive binding model to expedite screen-
ing of our system components. Coordinated identification of DBA:iDIOL pairs that
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