Gas cluster ion beam-secondary ion mass spectrometry (GCIB-SIMS) has shown the full potential of mapping intact lipids in biological systems with better than 10 μm lateral resolution. This study investigated further the capability of GCIB-SIMS in imaging high-mass signals from intact cardiolipin (CL) and gangliosides in normal brain and the effect of a controlled cortical impact model (CCI) of traumatic brain injury (TBI) on their distribution. A combination of enzymatic and chemical treatments was employed to suppress the signals from the most abundant phospholipids (phosphatidylcholine (PC) and phosphatidylethanolamine (PE)) and enhance the signals from the low-abundance CLs and gangliosides to allow their GCIB-SIMS detection at 8 and 16 μm spatial resolution. Brain CLs have not been observed previously using other contemporary imaging mass spectrometry techniques at better than 50 μm spatial resolution. High-resolution images of naive and injured brain tissue facilitated the comparison of CL species across three multicell layers in the CA1, CA3, and DG regions of the hippocampus. GCIB-SIMS also reliably mapped losses of oxidizable polyunsaturated CL species (but not the oxidation-resistant saturated and monounsaturated gangliosides) to regions including the CA1 and CA3 of the hippocampus after CCI. This work extends the detection range for SIMS measurements of intact lipids to above m/z 2000, bridging the mass range gap compared with MALDI. Further advances in high-resolution SIMS of CLs, with the potential for single cell or supra-cellular imaging, will be essential for the understanding of CL’s functional and structural organization in normal and injured brain.

The epidemiology suggests different risk factor patterns for BE and CE. Classification of BE and CE is difficult due to the nonspecific coding.

The feasibility of the use of piezoelectric drop-on-demand inkjet printing to prepare test materials for trace explosive analysis is demonstrated. RDX (1,3,5-trinitro-1,3,5 triazcyclohexane) was formulated into inkjet printable solutions and jetted onto substrates suitable for calibration of the ion mobility spectrometry (IMS) instruments currently deployed worldwide for contraband screening. Gravimetric analysis, gas chromatography/mass spectrometry (GC/MS), and ultraviolet-visible (UV-vis) absorption spectroscopy were used to verify inkjet printer solution concentrations and the quantity of explosive dispensed onto test materials. Reproducibility of the inkjet printing process for mass deposition of the explosive RDX (1,3,5-trinitro-1,3,5 triazcyclohexane) was determined to be better than 2% for a single day of printing and better than 3% day-to-day.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is an emerging technique for the characterization of biological systems. With the development of novel ion sources such as cluster ion beams, ionization efficiency has been increased, allowing for greater amounts of information to be obtained from the sample of interest. This enables the plotting of the distribution of chemical compounds against position with submicrometer resolution, yielding a chemical map of the material. In addition, by combining imaging with molecular depth profiling, a complete 3-dimensional rendering of the object is possible. The study of single biological cells presents significant challenges due to the fundamental complexity associated with any biological material. Sample preparation is of critical importance in controlling this complexity, owing to the fragile nature of biological cells and to the need to characterize them in their native state, free of chemical or physical changes. Here, we describe the four most widely used sample preparation methods for cellular imaging using ToF-SIMS, and provide guidance for data collection and analysis procedures.