Christoph Fahrni

Georgia Institute of Technology - US

Detecting trace metals within the complex chemical environment of biological systems requires highly sensitive microanalytical techniques. To this end, our research focuses on developing analytical probes and detection schemes for visualizing and quantifying biological trace metals with an emphasis on elucidating the role of zinc in cell division and embryonic development.

Fluorescence-based detection methods rank among the most widely used approaches for quantifying trace metals in biology. To take advantage of the increased depth-penetration, reduced autofluorescence background, and intrinsic 3D imaging capabilities offered by two-photon excitation fluorescence microscopy (TPEM), we developed a family of Zn(II)-selective emission-ratiometric probes tailored explicitly to the photophysical requirements of this technique. Moreover, we employ synchrotron X-ray fluorescence microscopy and microtomography to quantify the distribution of zinc and other trace elements at the single-cell level and in developing zebrafish embryos. While fluorescent probes can report on the dynamics of exchangeable zinc pools in live cells, X-ray fluorescence-based methods capture the total cellular zinc content within fixed specimens, thus providing complementary insights into the nature of biological zinc. More recently, we also embarked on identifying the cellular speciation of protein-bound zinc based on liquid chromatography interfaced with inductively coupled mass spectrometry (ICP-MS) and proteomics analysis.