Selective Fishing for Peptides with Antibody-Immobilized Acrylate Monoliths, Coupled Online with NanoLC-MS.

An online microfluidics-mass spectrometry platform was developed for determining proteotypic peptides from in-solution digested samples. Accelerated and selective sample cleanup was achieved by integrating proteotypic epitope peptide immunoextraction with nano liquid chromatography-tandem mass spectrometry (online IE-nanoLC-MS/MS). Ten individually prepared 180 μm inner diameter capillaries with ethylene glycol dimethacrylate- co-vinyl azlactone (EDMA- co-VDM) monoliths were immobilized with anti-protein antibodies that are used in routine immunoassays of the intact small cell lung cancer biomarker ProGRP. The resulting AB columns provided linearity correlation coefficients of 0.96-0.99 for protein amounts and concentrations of 10 pg to 5 ng and 0.5-250 ng/mL, respectively. The columns/platform gave relative peak area RSDs below 15%. The IE-nanoLC-MS/MS platform provided a limit of detection (LOD) of 520 pg/mL of ProGRP in human serum. The approach was applicable for other matrixes and proteins, i.e., primary glioblastoma cells and endogenous αV integrin chain. Thus, EDMA- co-VDM monoliths immobilized with antibodies are suited for automated peptide capture in microfluidic formats.