Opportunities in optical and electrical single-cell technologies to study microbial ecosystems

Abstract

New techniques are revolutionizing single-cell research, allowing us to study microbes at unprecedented scales and in unparalleled depth. This review highlights the state-of-the-art technologies in single-cell analysis in microbial ecology applications, with particular attention to both optical tools, i.e., specialized use of flow cytometry and Raman spectroscopy and emerging electrical techniques. The objectives of this review include showcasing the diversity of single-cell optical approaches for studying microbiological phenomena, highlighting successful applications in understanding microbial systems, discussing emerging techniques, and encouraging the combination of established and novel approaches to address research questions. The review aims to answer key questions such as how single-cell approaches have advanced our understanding of individual and interacting cells, how they have been used to study uncultured microbes, which new analysis tools will become widespread, and how they contribute to our knowledge of ecological interactions.

Raman cell sorting for single-cell research

“…A cell is the fundamental functional unit of life on earth, and the traditional study of cell populations often ignores the uniqueness of single cells ( Eldar and Elowitz, 2010 ; Spiller et al, 2010 ). In cell populations, even among different single cells with identical genomic information, there is remarkable phenotypic divergence, termed “cellular functional heterogeneity.” This cellular heterogeneity emerges as a significant feature of cell populations ( Ocasio et al, 2019 ; Mermans et al, 2023 ). Investigating the mechanisms at the single-cell level contributes to our understanding of cell differentiation and development ( Lo Celso et al, 2009 ; Sun et al, 2021 ), gene expression characteristics, and cellular features ( Cai et al, 2006 ; Zenobi, 2013 ).…”

“…In recent years, Raman cell sorting has gradually become a research hot spot in the field of single-cell sorting. As an emerging cell sorting method, single-cell Raman spectroscopy is usually coupled with cell manipulation and separation techniques to construct an integrated detection and sorting system ( Song et al, 2016 ; Mermans et al, 2023 ). This paper introduces various existing Raman cell sorting techniques, such as Raman-activated microfluidic sorting (RAMS) ( McIlvenna et al, 2016 ), Raman-tweezer cell sorting (RTCS) ( Lee et al, 2019 ), Raman-activated droplet cell sorting (RADS) ( Wang et al, 2017 ), and Raman-activated cell ejection (RACE) ( Jing et al, 2018 ), and describes their respective advantages and disadvantages.…”

Full-electric microfluidic platform to capture, analyze and selectively release single cells

“…Two categories of electrical devices for single-cell analysis currently being researched show a high potential: impedance flow cytometry (IFC) and complementary metal-oxide-semiconductor micro electrode arrays (CMOS MEAs). 5 Both techniques have a high throughput and are label-free. In IFC systems, the electrical impedance of cells is measured as they flow through a microfluidic channel.…”