Quantification of phosphorus in single cells using synchrotron X-ray fluorescence

Journal Article · 15 May 2010 · Journal of Synchrotron Radiation

DOI: https://doi.org/10.1107/s0909049510014020 · OSTI ID:1625693

Núñez-Milland, Daliángelis R. ^[1]; Baines, Stephen B. ^[2]; Vogt, Stefan ^[3]; Twining, Benjamin S. ^[4]

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1. Univ. of South Carolina, Columbia, SC (United States). Dept. of Chemistry and Biochemistry; DOE/OSTI
2. Stony Brook Univ., NY (United States). Dept. of Ecology and Evolution
3. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source. Experimental Facilities Division
4. Univ. of South Carolina, Columbia, SC (United States). Dept. of Chemistry and Biochemistry

Phosphorus is required for numerous cellular compounds and as a result can serve as a useful proxy for total cell biomass in studies of cell elemental composition. Single-cell analysis by synchrotron X-ray fluorescence (SXRF) enables quantitative and qualitative analyses of cell elemental composition with high elemental sensitivity. Element standards are required to convert measured X-ray fluorescence intensities into element concentrations, but few appropriate standards are available, particularly for the biologically important element P. Empirical P conversion factors derived from other elements contained in certified thin-film standards were used to quantify P in the model diatom Thalassiosira pseudonana, and the measured cell quotas were compared with those measured in bulk by spectrophotometry. The mean cellular P quotas quantified with SXRF for cells on Au, Ni and nylon grids using this approach were not significantly different from each other or from those measured spectrophotometrically. Inter-cell variability typical of cell populations was observed. Additionally, the grid substrates were compared for their suitability to P quantification based on the potential for spectral interferences with P. Nylon grids were found to have the lowest background concentrations and limits of detection for P, while background concentrations in Ni and Au grids were 1.8- and 6.3-fold higher. The advantages and disadvantages of each grid type for elemental analysis of individual phytoplankton cells are discussed.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1625693
• Journal Information: Journal of Synchrotron Radiation, Journal Name: Journal of Synchrotron Radiation Journal Issue: 4 Vol. 17; ISSN 0909-0495; ISSN JSYRES
• Publisher: International Union of CrystallographyCopyright Statement
• Country of Publication: United States
• Language: English