Comparison of time-gated surface-enhanced raman spectroscopy (TG-SERS) and classical SERS based monitoring of Escherichia coli cultivation samples

Martin Kögler, Andrea Paul, Emmanuel Anane, Mario Birkholz, Alex Bunker, Tapani Viitala, Michael Maiwald, Stefan Junne, Peter Neubauer*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)

Abstract

The application of Raman spectroscopy as a monitoring technique for bioprocesses is severely limited by a large background signal originating from fluorescing compounds in the culture media. Here, we compare time-gated Raman (TG-Raman)-, continuous wave NIR-process Raman (NIR-Raman), and continuous wave micro-Raman (micro-Raman) approaches in combination with surface enhanced Raman spectroscopy (SERS) for their potential to overcome this limit. For that purpose, we monitored metabolite concentrations of Escherichia coli bioreactor cultivations in cell-free supernatant samples. We investigated concentration transients of glucose, acetate, AMP, and cAMP at alternating substrate availability, from deficiency to excess. Raman and SERS signals were compared to off-line metabolite analysis of carbohydrates, carboxylic acids, and nucleotides. Results demonstrate that SERS, in almost all cases, led to a higher number of identifiable signals and better resolved spectra. Spectra derived from the TG-Raman were comparable to those of micro-Raman resulting in well-discernable Raman peaks, which allowed for the identification of a higher number of compounds. In contrast, NIR-Raman provided a superior performance for the quantitative evaluation of analytes, both with and without SERS nanoparticles when using multivariate data analysis.

Original languageEnglish
Pages (from-to)1533-1542
Number of pages10
JournalBiotechnology Progress
Volume34
Issue number6
DOIs
Publication statusPublished - 1 Nov 2018
Externally publishedYes
MoE publication typeA1 Journal article-refereed

Keywords

  • Escherichia coli
  • metabolite quantification
  • multivariate data analysis
  • surface-enhanced Raman spectroscopy (SERS)
  • time-gated Raman (TG-Raman)

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