title: A portable Raman acoustic levitation spectroscopic system for the identification and environmental monitoring of algal cells.
abstract: We report the coupling of a portable Raman spectrometer to an acoustic levitation device to enable environmental monitoring and the potential taxonomic identification of microalgae. Spectra of living cells were recorded at 785 nm using a fiber-optic probe coupled to a portable Raman spectrometer. The spectra exhibit an excellent signal-to-noise ratio and clearly show bands from chlorophyll a and beta-carotene. Spectra of levitated photobleached microalgae clearly show a reduction in chlorophyll a concentration relative to beta-carotene after 10 min of exposure to a quartz halogen lamp. Spectra recorded from levitated nitrogen-limited cells also show a significant reduction in bands associated with chlorophyll a, as compared to nitrogen-replete cells. To investigate the diagnostic capability of the technique, four species of microalgae were analyzed. Good quality spectra of all four species were obtained showing varying ratios of beta-carotene to chlorophyll. The combination of an acoustic levitation device and a portable Raman spectrometer shows potential as a taxonomic and environmental monitoring tool with direct application to field studies in remote environments.
authors.affiliation: Centre for Biospectroscopy and School of Chemistry, Monash University, 3800 Victoria, Australia. bayden.wood@sci.monash.edu.au
authors.forename: Bayden R
authors.initials: BR
authors.lastname: Wood
authors.forename: Philip
authors.initials: P
authors.lastname: Heraud
authors.forename: Slobodanka
authors.initials: S
authors.lastname: Stojkovic
authors.forename: Danielle
authors.initials: D
authors.lastname: Morrison
authors.forename: John
authors.initials: J
authors.lastname: Beardall
authors.forename: Don
authors.initials: D
authors.lastname: McNaughton
mesh_terms: D000460:Chlorophyta / Q000737:chemistry* / Q000145:classification / Q000187:drug effects; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods*; D009584:Nitrogen / Q000494:pharmacology; D010674:Pheophytins / Q000737:chemistry; D013059:Spectrum Analysis, Raman / Q000295:instrumentation* / Q000379:methods*
chemical_list: D010674:Pheophytins; D009584:Nitrogen