Mass Spectrometry Imaging Reveals That Gold Nanomaterial Surface Chemistry Affects Transport and Excretion in Mice over Time.

Nanoparticles (NPs) are versatile tools in various applications, particularly in the biomedical fields. To understand their behavior within biological systems, it is crucial to measure their distributions , especially as they interact with the immune system and excretory organs, to ensure their efficacy, safety, and clearance. Here, we demonstrate the unique capabilities of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) imaging for revealing the temporal redistribution of gold NPs (AuNPs) in key excretory organs. The quantitative and suborgan specific information available in LA-ICP-MS measurements indicate that positive AuNPs are more rapidly excreted through the hepatobiliary system of the liver than AuNPs having other surface charges. Using multielement image segmentation methods, we find that positive and zwitterionic AuNPs transition from the marginal zone of the spleen to the red pulp over time, indicating uptake by red pulp macrophages. In contrast, negative AuNPs redistribute more slowly, indicating different interactions with the immune system. Comparisons of high-resolution LA-ICP-MS images and fluorescence microscopy images on the same tissue sections reveal that positive AuNPs are excreted through the glomeruli of the kidney more effectively than are AuNPs with other charges. Overall, we demonstrate the power of LA-ICP-MS imaging for providing detailed information about AuNP fate at the suborgan level, which affords new insight into the interplay between surface chemistry and excretion pathways.