Mass sensitive imaging of bacterial biofilm composition using a water-gas cluster ion beam and novel neutral atom microscope.

Session

Mass Spectrometry Imaging Across Length Scales in Life and Physical Sciences - Providing Atomic and Molecular Information

Authors

Nick von Jeinsen (3, 1), Naoko Sano (1), Kate McHardy (1), Fauzy Nasher (2), David Ward (3, 1)

Affiliations

1. Ionoptika Ltd.
2. London School of Health and Tropical Medicine
3. University of Cambridge

Keywords

Biofilm

GCIB

J105

SIMS

Abstract text

Here we present recent work related to the study of biofilms; Microbial communities embedded in a 3D extracellular matrix. The matrix is composed of a complex array of extracellular polymeric substances that contribute to the unique attributes of biofilm lifestyle. Samples of bacteria and the biofilms they evolve are prepared and the growth arrested after a set period, with the resulting sample analysed with two distinct imaging techniques. We present data from water cluster secondary ion [SIMS] which offers a mass and depth resolution to aid understanding of the spatial composition of the biofilm by visualising the 3D structures within. In addition, we present the first images of bacteria using a new completely surface sensitive neutral beam microscopy technique (SHeM) which Ionoptika is commercially developing.

One of the key benefits of water cluster SIMS is its ability to achieve high depth resolution due to the low kinetic energy of the water clusters, which allows for the analysis of surface and subsurface structures with a high degree of precision [1]. The use of water clusters as the primary ion source minimises sample damage and fragmentation of high m/z species which are common issues with other ion beams [2,3]. Water cluster SIMS was used in Ionoptika’s J105 system with a beam spot size of 1.5um.

The results here show species consistent with biofilms [4] and tracing masses though the sample in 3D, allows the differentiation between known surface features, for example, biofilm components, fixative residue, growth medium and substrate. While the sample is destructively ablated by the ion beam, a 3D image is created. The novel SHeM imaging method is uniquely surface sensitive and is essentially entirely non-damaging and allows us to reveal new information about the areas of the substrate without need for coating and allowing, for example intermediate imaging to be performed followed by continuing surface processes on the same region of the sample.

Despite the work being at an early stage, a significant step forward has been made in delivering new methods for the study of a highly topical bio-samples that are of a wide interest and application. A combination of techniques employed such as those demonstrated here provide a multi-messenger approach which allows for an analysis where the sum of the parts is greater than the components.

References

[1] Tian, Hua, et al. "Multiomics imaging using high-energy water gas cluster ion beam secondary ion mass spectrometry [(H2O) n-GCIB-SIMS] of frozen-hydrated cells and tissue." Analytical Chemistry 93.22 (2021): 7808-7814.

[2] Yokoyama, Yuta, et al. "Peptide fragmentation and surface structural analysis by means of ToF-SIMS using large cluster ion sources." Analytical chemistry 88.7 (2016): 3592-3597.

[3] Muramoto, Shin, et al. "ToF-SIMS analysis of adsorbed proteins: principal component analysis of the primary ion species effect on the protein fragmentation patterns." The Journal of Physical Chemistry C 115.49 (2011): 24247-24255.

[4] Azeredo, Joana, et al. "Critical review on biofilm methods." Critical reviews in microbiology 43.3 (2017): 313-351.