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. Author manuscript; available in PMC: 2021 Mar 16.
Published in final edited form as: Angew Chem Int Ed Engl. 2020 Jan 24;59(12):4678–4683. doi: 10.1002/anie.201914120

Figure 1. Structural, spectral and photoacoustic characterization of PTX-MB.

Figure 1.

(a) Mass spectrum of HPLC purified sample of PTX-MB shows the molecular ion peak (m/z = 1249.79, C88H73N4O17S+). (b) The photoacoustic signal intensity (ʎexc = 640 nm) shows a linear relationship with concentration of PTX-MB (4.91×10−5 to 4.91×10−6 mil L−1 in PBS containing 20% v/v mice serum, R2 = 0.87). (c) The absorbance spectrum of PTX-MB (black square) and PTX-LMB (red circle) (7.3×10−5 M in PBS with 20% v/v mice serum) shows approximately 20-fold difference in absorbance at 640 nm. Inset in (c) shows photos of 7.3×10−5 M solutions of PTX-MB (blue) and PTX-LMB (faint blue). (d) The photoacoustic spectra shows an increase in photoacoustic intensity in the PTX-MB spectrum from 680 – 760 nm. (e) Photoacoustic imaging of PTX-MB and PTX-LMB solutions (7.3×10−5 M in PBS with 20% mice serum) shows a 6.88-fold increase of PTX-MB at 680 nm. The inset in (e) is the photoacoustic image of a phantom. (f) The illustration shows the redox switching between PTX-MB and PTX-LMB leading to photoacoustic signal. Scale bars = 2 mm.