Multiplexed imaging of nanoparticles in tissues using laser desorption/ionization mass spectrometry

Imaging of nanomaterials in biological tissues provides vital information for the development of nanotherapeutics and diagnostics. Multiplexed imaging of different nanoparticles (NPs) greatly reduces costs, the need to use multiple animals, and increases the biodistribution information that can enhance diagnostic applications and accelerate the screening of potential therapeutics. Various approaches have been developed for imaging NPs; however, the readout of existing imaging techniques relies on specific properties of the core material or surface ligands, and these techniques are limited because of the relatively small number of NPs that can be simultaneously measured in a single experiment. Here, we demonstrate the use of laser desorption/ionization mass spectrometry (LDI-MS) in an imaging format to investigate surface chemistry dictated intraorgan distribution of NPs. This new LDI-MS imaging method enables multiplexed imaging of NPs with potentially unlimited readouts and without additional labeling of the NPs. It provides the capability to detect and image attomole levels of NPs with almost no interferences from biomolecules. Using this new imaging approach, we find that the intraorgan distributions of same-sized NPs are directly linked to their surface chemistry.