A Barcoding Strategy for Pooled Single-Cell LA-ICP-TOFMS Analysis of Metal-Containing Therapeutics

Laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOFMS) enables the quantitative imaging of metal-based therapeutics with cellular resolution. Despite its analytical power, systematic screening of metal-containing anticancer agents remains limited by the substantial time, cost, and labor required for cell handling, staining, and analysis. Here, we present a barcoding strategy that allows us to pool multiple experiments together and analyze them simultaneously. Our labeling approach combines wheat germ agglutinin (WGA) with lanthanide-labeled anti-WGA barcodes, enabling robust discrimination of experimental conditions. Following LA-ICP-TOFMS measurement, pooled data sets can be processed using MeXpose, a data processing pipeline for single cells, to accurately assign each cell to its original barcode, i.e., experiment. In this study, we applied this novel strategy to investigate the uptake of BOLD-100 and oxaliplatin in HCT116 wild-type (WT) and oxaliplatin-resistant (OxR) colorectal cancer cells using different drug concentrations. Pooling 10 experiments into a single analytical run allowed us to reduce consumable use (mainly argon for the ICP and antibody usage if stained), measurement time, and downstream processing while increasing data consistency. Barcoding-enabled single-cell analysis confirmed a substantial reduction in oxaliplatin uptake in oxaliplatin-resistant HCT116 cells compared with the WT cell line, whereas BOLD-100 uptake was affected to a much lesser extent. These results demonstrate the utility of this strategy for the efficient and scalable assessment of metal-based therapeutics.