title: Laser desorption/ionization mediated by bionanostructures from microalgae.
abstract: BACKGROUND
  Organic matrices are the state-of-the-art ionization mediators in Laser Desorption/Ionization Mass Spectrometry (LDI-MS). Despite improvements in understanding matrix chemistry, interfering matrix-related signals complicate the analysis. Surface-assisted LDI techniques like desorption/ionization on silicon (DIOS) or nanostructure initiator mass spectrometry (NIMS) provide promising alternatives but rely often on elaborate materials.
  
  
  METHODS
  We introduce nanopatterned biomineralized cell walls of microalgae as easily accessible biological surfaces that support the ionization of embedded molecules in LDI-MS. Microalgae cell walls were cleaned through oxidation and washing before pipetting on a stainless-steel matrix-assisted laser desorption/ionization (MALDI) target. Added molecules were efficiently ionized in positive and negative ionization mode in common MALDI sources. The method was rigorously validated by comparison with established MALDI experiments.
  
  
  RESULTS
  Ionization of PEG600, D-sphingosine and raffinose was successfully mediated by nanostructured cell wall preparations from two different microalgae. Without any change in protocol, steric acid could be detected in the negative ionization mode. Ionization is also supported by commercially available celite, a material containing mineralized diatom cell walls. Characteristic ingredients of fresh coffee were detected in LDI-MS after pipetting it on celite without further sample preparation. Caffeine and saccharose were detected in positive and characteristic fatty acids in negative ionization mode. Detection limits were comparable to established MALDI experiments.
  
  
  CONCLUSIONS
  Bionanostructure-enhanced ionization allows the analysis of a diverse selection of analytes including polymers, sugars, amino alcohols, and organic acids without interfering matrix signals. We also show that celite, a commercially available porous material containing mineralized algal bionanostructures, supports LDI-MS.
authors.affiliation: Institute for Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Lessingstraße 8, 07743, Jena, Germany.
authors.forename: Tino
authors.initials: T
authors.lastname: Jaschinski
authors.forename: Aleš
authors.initials: A
authors.lastname: Svatoš
authors.forename: Georg
authors.initials: G
authors.lastname: Pohnert
mesh_terms: D002110:Caffeine / Q000032:analysis; D002473:Cell Wall / Q000737:chemistry; D003069:Coffee / Q000737:chemistry; D007692:Diatomaceous Earth / Q000737:chemistry; D017377:Diatoms / Q000737:chemistry; D004141:Dinoflagellida / Q000737:chemistry; D031321:Hydrocharitaceae / Q000737:chemistry / Q000166:cytology; D057230:Limit of Detection; D058086:Microalgae / Q000737:chemistry* / Q000166:cytology; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D011801:Quinic Acid / Q000032:analysis; D011887:Raffinose / Q000032:analysis; D015203:Reproducibility of Results; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000295:instrumentation* / Q000379:methods*; D013110:Sphingosine / Q000032:analysis
chemical_list: D003069:Coffee; D011801:Quinic Acid; D002110:Caffeine; D011092:Polyethylene Glycols; D007692:Diatomaceous Earth; D011887:Raffinose; D013110:Sphingosine