Fig. 1.

Fluorescence responses of AF488-iRGDK-dab (10 μM) to (a) various concentrations of DTT (0–640 μM) under the excessive trypsin condition (10 μg/mL) in PBS (pH 7.4), and (b) various concentrations of trypsin (0–10 μg/mL) under the excessive DTT condition (640 μM) in PBS (pH 7.4). The fluorescence spectra were obtained after mixing at 37 °C for 1 h (ex/em = 488/515 nm). (c) Quenching stability of AF488-iRGDK-dab (10 μM) at various pH (4.4–12) and human serum solution. Quenching efficiencies were estimated based on the fluorescence intensity of AF488-iRGDK-dab after mixing at 37 °C for 2 h (ex/em = 488/515 nm).