title: Quantification of antibiotic in biofilm-inhibiting multilayers by 7.87 eV laser desorption postionization MS imaging.
abstract: The potential of laser desorption postionization mass spectrometry (LDPI-MS) imaging for small molecule quantification is demonstrated here. The N-methylpiperazine acetamide (MPA) of ampicillin was adsorbed into polyelectrolyte multilayer surface coatings composed of chitosan and alginate, both high molecular weight biopolymers. These MPA-ampicillin spiked multilayers were then shown to inhibit the growth of  Enterococcus faecalis  biofilms that play a role in early stage infection of implanted medical devices. Finally, LDPI-MS imaging using 7.87 eV single-photon ionization was found to detect MPA-ampicillin within the multilayers before and after biofilm growth with limits of quantification and detection of 0.6 and 0.3 nmol, respectively. The capabilities of LDPI-MS imaging for small molecule quantification are compared to those of MALDI-MS. Furthermore, these results indicate that 7.87 eV LDPI-MS imaging should be applicable to quantification of a range of small molecular species on a variety of complex organic and biological surfaces. Finally, while MS imaging for quantification was demonstrated here using LDPI, it is a generally useful strategy that can be applied to other methods.
authors.affiliation: Department of Chemistry, MC 111, University of Illinois at Chicago, Chicago, Illinois 60607, United States.
authors.forename: Melvin
authors.initials: M
authors.lastname: Blaze M T
authors.forename: Artem
authors.initials: A
authors.lastname: Akhmetov
authors.forename: Berdan
authors.initials: B
authors.lastname: Aydin
authors.forename: Praneeth D
authors.initials: PD
authors.lastname: Edirisinghe
authors.forename: Gulsah
authors.initials: G
authors.lastname: Uygur
authors.forename: Luke
authors.initials: L
authors.lastname: Hanley
mesh_terms: D000081:Acetamides / Q000737:chemistry; D000327:Adsorption; D000667:Ampicillin / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D013293:Enterococcus faecalis / Q000187:drug effects / Q000502:physiology; D007834:Lasers; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D057054:Molecular Imaging / Q000379:methods*
chemical_list: D000081:Acetamides; D000900:Anti-Bacterial Agents; D000667:Ampicillin