Tissue Validation by DESI-MSI
A commercial DESI system (Prosolia, Indianapolis, U.S) was employed for
tissue imaging. N, N-dimethyl formamide-acetonitrile (1:1, v/v) was used
as the spray solvent with a flow rate at 1.0 μL/min and nebulizer gas
pressure at 1.6 MPa. The impact angle between sprayer and section
mounting stage was 56°. High voltage of +4.0 kV was provided by the mass
spectrometer and applied onto the sprayer to generate the electrospray
for desorbing and ionizing the components across the tumor cryosection
(12 μm). Target ion image reconstruction was achieved using Massimager
(Chemmind Technologies Co., Ltd, China).