Boron‐Containing Probes for Non‐optical High‐Resolution Imaging of Biological Samples

Light on by boron: Tagging cellular proteins with carboranes enables their visualization with non‐optical techniques such as nanoSIMS. Flexible protocols for the incorporation of the tags in a specific manner are shown. By combining the synthesis of carborane derivatives with biotechnological tools, high densities of the probes could be obtained inside cells, enabling relatively easy labeling and detection.

Abstract

Boron has been employed in materials science as a marker for imaging specific structures by electron energy loss spectroscopy (EELS) or secondary ion mass spectrometry (SIMS). It has a strong potential in biological analyses as well; however, the specific coupling of a sufficient number of boron atoms to a biological structure has proven challenging. Herein, we synthesize tags containing closo‐1,2‐dicarbadodecaborane, coupled to soluble peptides, which were integrated in specific proteins by click chemistry in mammalian cells and were also coupled to nanobodies for use in immunocytochemistry experiments. The tags were fully functional in biological samples, as demonstrated by nanoSIMS imaging of cell cultures. The boron signal revealed the protein of interest, while other SIMS channels were used for imaging different positive ions, such as the cellular metal ions. This allows, for the first time, the simultaneous imaging of such ions with a protein of interest and will enable new biological applications in the SIMS field.

from A via a.sfakia on Inoreader http://bit.ly/2sn4uFL