Figure 2

Fluorescent ICG-pHLIP and dark quencher QC1-pHLIP have comparable optoacoustic intensities at the same concentration in tissue mimicking phantoms. (a) An optoacoustic imaging flow setup using soft-tissue mimicking phantoms (right) was used with the MSOT whole animal imaging setup (left). (b) Optoacoustic characterizations of ICG-pHLIP and QC1-pHLIP at varying concentrations (2 µM, 5 µM, 10 µM, 15 µM and 20 µM) in DMSO. Optoacoustic intensities at 680 nm were overlaid with the spectrally unmixed signals of ICG-pHLIP (green) or QC1-pHLIP (cyan). (c) The optoacoustic spectra (a.u.) of ICG-pHLIP (left) and QC1-pHLIP (right). (d) The UV/Vis absorbance spectra of ICG-pHLIP and QC1-pHLIP at 5 µM deviates from the optoacoustic spectra of ICG-pHLIP and QC1-pHLIP (e, middle) taken at the same concentrations (15 µM). (f, right) Classical least square (CLS) fit at varying concentrations of the two pHLIPs after multi-spectral unmixing with the spectra references shown in (e, middle).