Surface preparation strategies for improved parallelization and reproducible MALDI-TOF MS ligand binding assays.

Immunoassays are employed in academia and the healthcare and biotech industries for high-throughput, quantitative screens of biomolecules. We have developed monolayer-based immunoassays for MALDI-TOF MS. To improve parallelization, we adapted the workflow to photolithography-generated arrays. Our work shows Parylene-C coatings provide excellent "solvent pinning" for reagents and biofluids, enabling sensitive MS detection of immobilized components. With a unique MALDI-matrix crystallization technique we show routine interassay RSD <10% at picomolar concentrations and highlight platform compatibility for relative and label-free quantitation applications. Parylene-arrays provide high sample densities and promise screening throughputs exceeding 1000 samples/h with modern liquid-handlers and MALDI-TOF systems.