Direct assay of Aplysia tissues and cells with laser desorption/ionization mass spectrometry on porous silicon

Desorption/ionization on porous silicon (DIOS) is a form of laser desorption mass spectrometry that allows for the direct mass analysis of a variety of analytes without the addition of organic matrix. Protocols are described for the direct analysis of exocrine tissue and single neurons using DIOS-MS. The atrial gland of Aplysia californica was blotted on to porous silicon and analyzed with DIOS-MS in the range m/z 1000-4000. The ability to culture invertebrate neurons directly on porous silicon is also presented. Isolated bag cells regenerated neuronal processes in culture on porous silicon. DIOS-MS allowed the direct detection of the peptides contained in individual cultured neurons indicating that with appropriate protocols, DIOS can be used with biological samples with considerable thickness.