Instrument-free enrichment and detection of phosphopeptides using paper-based Phos-PAD.

The facile detection of phosphopeptides is important for clinical screening and phosphoproteomic research. This work develops an instrument-free, cost-effective, convenient paper-based method for quantitative analysis of phosphorylated peptides. With a novel portable device, Phos-PAD, this method can achieve selective enrichment and colorimetric detection of phosphopeptides within 15 min TiO nanoparticle-based chemisorption and tetrabromophenol blue-based colorimetric assay were integrated into the single paper-based analytical device.