Subcellular localization of boron in cultured melanoma cells by electron energy-loss spectroscopy of freeze-dried cryosections.

Boron neutron capture therapy (BNCT) is based on the ability of the non-radioactive isotope 10B to capture thermal neutrons and to disintegrate instantaneously. This reaction opens a way to selectively destroy tumour cells after specific uptake of 10B. In this paper, a method based on electron energy-loss spectroscopy is presented for detecting and quantifying boron in freeze-dried cryosections of human melanoma cells. A practical detection limit of around 6 mmol kg-1 in 0.1- micro m2 areas is estimated using specimens prepared from standard boron solutions. Preliminary results of boron mapping in the spectrum-imaging acquisition mode reveal boron penetration and probably spot-like accumulation within melanoma cells when exposed to culture medium containing sodium borocaptate.