Bioimaging of metals and biomolecules in mouse heart by laser ablation inductively coupled plasma mass spectrometry and secondary ion mass spectrometry

Bioimaging mass spectrometric techniques allow direct mapping of metal and biomolecule distributions with high spatial resolution in biological tissue. In this study laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) was used for imaging of transition metals (Fe, Cu, Zn, Mn, and Ti), alkali and alkaline-earth metals (Na, K, Mg, and Ca, respectively), and selected nonmetals (such as C, P, and S) in native cryosections of mouse heart. The metal and nonmetal images clearly illustrated the shape and the anatomy of the samples. Zinc and copper were inhomogeneously distributed with average concentrations of 26 and 11 μg g^-1, respectively. Titanium and manganese were detected at concentrations reaching 1 and 2 μg g^-1, respectively. The highest regional metal concentration of 360 μg g ^-1was observed for iron in blood present in the lumen of the aorta. Secondary ion mass spectrometry (SIMS) as an elemental and biomolecular mass spectrometric technique was employed for imaging of Na, K, and selected biomolecules (e.g., phosphocholine, choline, cholesterol) in adjacent sections. Here, two different bioimaging techniques, LA-ICPMS and SIMS, were combined for the first time, yielding novel information on both elemental and biomolecular distributions.