Desorption and ionization mechanisms and signal enhancement in surface assisted laser desorption ionization mass spectrometry (SALDI-MS)

Surface assisted laser desorption ionization mass spectrometry (SALDI-MS) has been recognized as one of the prominent techniques in mass analysis of small molecules as well as large nonvolatile molecules since it bears many advantages compared to matrix assisted laser desorption ionization mass spectrometry. The use of SALDI-MS has been increasing for small molecules analysis with the development of new substrates materials for ionization such as porous silicons and nanomaterials. While most of researches about SALDI-MS are focusing on the development of new substrate materials, not much of works has been done for the verification of ionization mechanism of SALDI-MS. In this article, we reviewed the characteristics of SALDI-MS such as desorption/ionization mechanisms, signal enhancement by inorganic matrix, and recent trends on the development of new efficient matrix substrates. Among the reviewed ionization mechanisms, the laser ablation followed by generation of laser-induced plasma and shock wave is suggested to be more plausible mechanism in the desorption and ionization process of SALDI-MS, while other mechanisms are also recognized to contributes to the desorption and ionization process. Recent development of efficient substrate materials for SALDI-MS by adopting nanoparticles, nanomaterials, metal organic frameworks, and their combination was also reviewed.