Abstract: Boronic acid and its derivatives have a proven record as synthetic receptors and probes. It has also been known that when boronic acids bind sugars (e.g., glucose), there is a conductivity change (or impedance) . Binding constants between boronic acids and sugars are normally in the range of 0.1 mM to 1 mM . Therefore, properly designed synthetic receptors comprised of boronic acids may be used as the sensing element for glucose sensors and sorbitol sensors.
We tested the pH change as a result of interaction between phenylboronic acid (PBA, 0.25mM) and sorbitol at various concentrations. Results show that an approximately linear relationship was obtained. We then synthesized molecularly imprinted polymers (MIP) using sorbitol as the template.
The MIP showed high specific selectivity for sorbitol in a solution containing sorbitol, glucose and sucrose as determined by HPLC analysis. When we tested the pH change as a result of interaction between the MIP and sorbitol, results show an approximately linear relationship up to 1:1 ratio (0.1 mM). MIP specific for glucose was also prepared. Conductivity change upon binding of glucose with this MIP was also tested. Resutls show that there appears to be a linear relationship up to 1:1 ratio (0.1 mM).
In summary, preliminary results show that the MIPs are selective for their template molecules. Binding of their target molecules causes either a pH change or conductivity change that appear to be proportional to its concentration up to 1 to 1 ratio. These MIPs have potential to be used as receptors for glucose and sorbitol sensing.
Template and target information: glucose, sorbitol