carla newman oral presentation (OB3-Wed2-1-4)
Probing the distribution and effect of antibiotics in bacteria using the 3D OrbiSIMS
1 GSK - the university of Nottingham, 61 valerian way, SG5 4ET hitchin, United Kingdom
2 NPL, Hampton road, TW11 0LW London, United Kingdom
3 GSK, gunnerls wood road, SG1 2NY stevenage, United Kingdom
4 The university of Nottingham, wollaton road, NG8 1BB Nottingham, United Kingdom
Time-of-flight Secondary ion mass spectrometry (ToF-SIMS) is a powerful bioanalytical technique that has the ability to generate high spatial resolution images in which each pixel has a full mass spectrum associated with it. Despite this, the balance between spatial resolution and mass resolution can be hard to achieve and needs to be decided on a case by case basis. Bacterial analysis can be particularly challenging, as the size of the analyte necessitates the highest spatial resolution. This can significantly impact the quality and resolution of the mass spectra, which invalidates any accurate assignments of endogenous molecules.
The new 3D OrbiSIMS allows the acquisition of spectra with extremely high mass resolution (240000 at 200 m/z). The <1ppm mass accuracy of the Orbitrap analyser generates spectra that can then be used to formulate assignments of endogenous molecules such as metabolites and lipids. Furthermore, the MS/MS capability adds extra confidence to the assignments.
Bacillus Calmette-Guerin (BCG) was chosen for this study as it is extensively used as a tuberculosis model. Developing antibiotic resistance necessitates the need to find new efficacious molecules to treat this serious condition. The ability to image bacteria at high spatial resolution while simultaneously obtaining high mass resolution spectra can provide insight on bacteria at a molecular level. This is fundamental to not only determine the location of drug like molecules but also detect changes in endogenous molecules between compound treated and untreated bacteria.