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

Boron has been occasionally employed as a marker for specific structures in imaging technologies such as electron energy loss spectroscopy (EELS) or secondary ion mass spectrometry (SIMS), in material science. It has a strong potential as a marker in biological analyses as well. However, coupling sufficient boron atoms to a biological structure in a specific fashion has proven challenging. Here we solved this problem by generating tags containing closo‐1,2‐dicarbadodecaborane (ortho‐carborane), coupled to soluble peptides by solid‐phase synthesis. The carborane tags were integrated in specific proteins by click chemistry in mammalian cells, and were also coupled to nanobodies, to be used in immunocytochemistry experiments. They 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, as the cellular metal ions. Our work allows, for the first time, the simultaneous imaging of such ions together with a protein of interest, and will therefore enable new biological applications in the SIMS field.

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