Comparison of C₆₀ and GCIB primary ion beams for the analysis of cancer cells and tumour sections

Abstract

aWe have implemented a gas cluster ion beam (GCIB) system developed by Ionoptika Ltd (Southampton, UK) with sufficient control to allow us to exploit the unique capabilities of our J105 instrument for imaging and depth profiling. The J105 allows us to use the GCIB as continuous primary ion beam, thereby overcoming the issues associated with pulsing these slow moving, mixed species beams. We have performed a direct comparison with C 60 ions on the same samples in the same instrument. The GCIB beams are more difficult to focus than the C 60 + ion beam, making single-cell imaging difficult, although spot sizes of 15-20 mm are readily obtainable for Ar 1000 and Ar 2000 , providing good resolution for larger area imaging on tissue section/biopsy samples. In this paper, we present results from the assessment of these new beams as primary ions for the analysis of 'real', complex biological systems. Initial spectra and those following increased primary ion bombardment were compared for in vitro cultured cells deposited on silicon and cryo-sectioned tumour samples originating in vivo.

Latest applications of 3D ToF-SIMS bio-imaging

“…47,48 Rabbani et al reported improved molecular ion signal levels from lipid and neuropeptide standard samples after continued bombardment with 20 kV Ar cluster beams. 49 Improved molecular signal levels compared with C 60 bombardment for lipid species in cell and tumor samples have been reported 50 and most recently Bich and co-workers showed persistent lipid signal when a depth profile was performed through a rat brain section that was sliced at 14 lm thickness and analyzed after freeze drying when the tissue thickness had been reduced to approximately 1.2 lm. 51 The implication is that these new beams will offer improved performance in a wide range of 3D biological imaging experiments.…”

Correlated imaging – a grand challenge in chemical analysis

“…74 Freeze-fracturing cells is one effective way to accomplish this, 75 and in-source manipulation methods offer effective alternatives. Polyatomic “cluster” primary ion beams such as C 60 or Ar 2000 excel at removing material while causing little sample damage, 76, 77 thus serving as effective etching tools to interrogate cell contents. 78 Similarly, orthogonal fast ion beam milling can shave off nanometer-scale layers of material between imaging scans.…”

Maximising the potential for bacterial phenotyping using time‐of‐flight secondary ion mass spectrometry with multivariate analysis and Tandem Mass Spectrometry

“…[6][7][8][9] Recently, gas cluster ion beams such as Ar n (n = 500-3000) have been introduced and have shown further benefits for organic analysis. [10,11] Multivariate analysis techniques have become popular in the analysis of ToF-SIMS data, and a variety of supervised and unsupervised methods have been employed for image and spectral analysis for classification, image contrast improvement and as a tool for data interpretation and reduction. [12][13][14][15] This study was aimed at optimising sample preparation and data pre-processing for bacterial analysis with ToF-SIMS and principal components analysis (PCA) to study small chemical differences ultimately in bacterial phenotypes.…”