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Updated: May 5, 2026

Three-dimensional Optical-resolution Photoacoustic Microscopy
Published on: May 3, 2011
Calcium Sensor for Photoacoustic Imaging
Sheryl Roberts, Markus Seeger, Yuanyuan Jiang
1CSSB, 22607 Hamburg and Institute for Biophysical Chemistry, Hannover Medical School , 30625 Hannover, Germany.
Abstract:
We introduce a selective and cell-permeable calcium sensor for photoacoustics (CaSPA), a versatile imaging technique that allows for fast volumetric mapping of photoabsorbing molecules with deep tissue penetration. To optimize for Ca2+-dependent photoacoustic signal changes, we synthesized a selective metallochromic sensor with high extinction coefficient, low quantum yield, and high photobleaching resistance. Micromolar concentrations of Ca2+ lead to a robust blueshift of the absorbance of CaSPA, which translated into an accompanying decrease of the peak photoacoustic signal. The acetoxymethyl esterified sensor variant was readily taken up by cells without toxic effects and thus allowed us for the first time to perform live imaging of Ca2+ fluxes in genetically unmodified cells and heart organoids as well as in zebrafish larval brain via combined fluorescence and photoacoustic imaging.
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