ICP-MS for Multiplexed Protein Determination in Extracellular Vesicles from APP/PS1 Mice Blood Serum–Application to a Zn Supplementation Pilot Study

Neurodegenerative diseases represent a significant challenge due to their complex etiology, late diagnosis, and lack of effective treatments. Extracellular vesicles (EVs) have emerged as promising carriers of disease biomarkers, especially proteins, but their low abundance in biological fluids complicates their detection. Here, we present a novel strategy for the multiplexed quantitative determination of EV-associated proteins in blood serum from APP/PS1 transgenic mice, a model of Alzheimer's disease. The method combines inductively coupled plasma-time-of-flight mass spectrometry (ICP-ToFMS) with competitive immunoassays using metal nanocluster-labeled (AuNCs, PtNCs, IrNCs) antibodies targeting Alpha-Actinin 1 (ACTN), Galectin-3-binding protein (LG3BP), and Moesin (MSN). EVs were isolated using an optimized ultracentrifugation protocol to reduce the level of serum protein contamination. Proteomic screening identified target proteins with a known relevance to neurodegeneration, and the developed assay achieved detection limits in the low femtomolar range. The approach was applied to a pilot study on Zn supplementation in 16-month-old APP/PS1 mice, revealing sex-dependent and genotype-specific differences in protein expression but sex-independent patterns in regulatory mechanisms (especially for MSN and LG3BP). Among the studied markers, MSN levels showed statistically significant differences with Zn treatment in male homozygous mice. This work demonstrates the potential of ICP-MS for sensitive and multiplexed biomarker quantification in EVs, supporting its use in neurodegenerative research and supplementation studies.