Multidimensional Analysis of Single Algal Cells by Integrating Microspectroscopy with Mass Spectrometry

Abstract

We demonstrate a facile label-free approach for performing multidimensional chemical analysis on individual single-cell organisms by combining optical, fluorescence, and Raman microspectroscopy with matrix-free laser desorption/ionization mass spectrometry (MS). Single unicellular algae are seeded on a bare stainless steel plate and analyzed microspectroscopically. This provides information on the content and distribution of photoactive species, such as β-carotene, as well as chlorophyll and other components of the photosynthetic apparatus. Exactly the same cells are then analyzed by mass spectrometry in the negative ion mode. Phospholipid species are readily ionized by laser desorption/ionization of intact cells, without the need for an auxiliary matrix. This not only facilitates sample preparation but also preserves high spatial resolution and high sensitivity. Using this method, we were able to study the content and arrangement of proplastids and photosystem components, as well as the amounts of various phospholipid species in individual algal cells. The methodology can be used in the fundamental biological studies on these unicellular organisms, which require information on the internal structure as well as the chemical composition of individual cells.

Online Analysis of Single Cyanobacteria and Algae Cells under Nitrogen-Limited Conditions Using Aerosol Time-of-Flight Mass Spectrometry

“…The identities of the majority of these peaks are unknown at this time, but a brief discussion of the peaks of interest is given here and in the Supporting Information. In the lower mass range (<200 m/z), there is evidence of metals ( 23 Na + and 40 Ca + ) and organic fragment ions ( 12 C + , 15 To demonstrate the wide applicability of the technique for the analysis of a broad range of cell types and cell sizes with relative ease, various cell strains were aerosolized and laser ablated in the ATOFMS. The cell name, type, their weighted average APS, and ATOFMS particle sizes are given in Table 1.…”

Correlated imaging – a grand challenge in chemical analysis

“…Images of individual algal cells provided information on the content and distribution of photosynthetic molecules and phospholipids. 66 Raman and mass spectrometric imaging have also been applied in environmental/geological research. CRM and SIMS images from the same sample at the same location were successfully acquired in a study of Akilia supracrustal rocks, allowing the presence and physical and molecular composition of apatite-based graphitic inclusions in the rocks to be confirmed.…”

Structural and Spatial Analysis of Carotenoids in a Single Cell Monitored by Raman Spectroscopy

“…In Chlamydomonas, due to known birefringence of its eye, the eyespot was measured with the polarized light, showing that pigment molecules are arranged with the long axis along the elongated direction of the eyespot and parallelly to the body axis [31]. Raman and fluorescence microspectroscopy, in addition to matrix-free laser desorption/ionization mass spectrometry were applied to the analysis of composition and distribution of photosynthetic apparatus components in a single cell of Euglena gracilis and Chlamydomonas reinhardtii [32]. high-spatial resolution ( ca.…”