A radiate microstructure MALDI chip for sample concentration and detection.

Although matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) analysis is an important tool for analyzing and characterizing biomolecules of varying complexity, the sensitivity of MALDI-TOFMS is dependent on proper preparation of the sample, a process that is oftentimes problematic and requires considerable expertise. In this study, we have developed a radiate microstructure chip on which samples can be concentrated for analysis by MALDI-TOFMS. The sample/matrix mixture was deposited onto the central space of the well on the chip and allowed to dry. Microscopic analysis confirmed that the applied samples were confined to the central zone. Sample spots focused on the chip were much smaller than those on an unmodified plate with the same total volume. Optimizing processes of several preparation factors were also performed to ensure matrix homogeneity in our chip. Analysis of the samples with MALDI-TOFMS showed that the signals from samples on our chip were significantly greater than those on the unmodified plate. The feasibility of using this chip to detect peptides and phosphopeptides was also demonstrated.