Figure 3.
Phenylalanine-detecting E-AB sensor is rapid, quantitative, and specific. (A) The sensor responds with a time constant of less than 1 min at physiological (i.e., above 120 μM) concentrations. (B) The sensor achieves clinically relevant specificity. e.g., when it is tested against either tyrosine or a mix of five amino acids (glutamine, histidine, proline, arginine, and alanine), it does not produce a detectable signal change until the concentration rises above 10 μM. In contrast, the sensor does cross-react with tryptophan. Given, however, the physiological levels of this amino acid and the 1:1000 dilution, we employ no interference from tryptophan is expected.