Single-cell imaging of AuNPs and AgNPs by near-field desorption ionization mass spectrometry
Nanoparticles (NPs) have prospective applications in the field of biomedicine and biotechnology. Considering that the therapeutic effect of NPs is closely related to their location inside cells, the study of the intracellular distribution of NPs in high spatial resolution is crucial. Herein, near-field desorption ionization mass spectrometry (NDI-MS) was applied to AuNP and AgNP imaging in single cells. A mean crater diameter of 310 nm on the cellular surface and single cell imaging with 250 nm pixel size were achieved. Some compounds originating from surface ligands or endogenous substances were simultaneously imaged with AuNPs. Additionally, the location of the AuNPs was compared with the images from confocal laser scanning microscopy (CLSM), which reaches a good agreement. NDI-MS shows a unique advantage of simultaneously imaging NPs and ligands at subcellular lateral resolution. It can be extended to other NP systems and thus used as a general method for the insightful exploration of the engineered NPs in biomedicine.