Samples were prepared in 1 mL Eppendorf tubes using equal volumes of 1-octanol and HEPES buffer (50mM HEPES, 100 mM NaCl, pH 7.4) or HEPES buffer containing BSA (0.25 mM). An aliquot of ICB or ICG (10 µM) was pipetted into the 1-octanol layer, and the biphasic mixture was vigorously shaken for 15 seconds, then centrifuged at 1000 g for 2 minutes to cleanly separate the two phases. A 250 µL aliquot from each phase was transferred to a 96-well plate, and the absorbance at 780 nm for ICG or 680 nm for ICB was recorded. LogP was determined using the formula P = log(Aoctanol/Abuffer) where Aoctanol = absorbance of dye in octanol phase and Abuffer = absorbance of dye in buffer phase at the relevant wavelength. All measurements were performed in triplicate.