Characterization of a novel miniaturized burst-mode infrared laser system for IR-MALDESI mass spectrometry imaging

Abstract

Laser systems are widely used in mass spectrometry as sample probes and ionization sources. Mid-infrared lasers are particularly suitable for analysis of high water content samples such as animal and plant tissues, using water as a resonantly excited sacrificial matrix. Commercially available mid-IR lasers have historically been bulky and expensive due to cooling requirements. This work presents a novel air-cooled miniature mid-IR laser with adjustable burst-mode output and details an evaluation of its performance for mass spectrometry imaging. The miniature laser was found capable of generating sufficient energy for complete ablation of animal tissue in the context of an IR-MALDESI experiment with exogenously added ice matrix, yielding several hundred confident metabolite identifications. Graphical abstract The use of a novel miniature 2.94 μm burst-mode laser in IR-MALDESI allows for rapid and sensitive mass spectrometry imaging of a whole mouse.

Artemisinin Biosynthesis in Non-glandular Trichome Cells of Artemisia annua

“…In addition, laser dissection was performed to isolate leaf areas for mass spectrometry imaging. Samples were brought to the IR-MALDESI system, the principles and specificities of which have been enumerated in detail in previous reports (Robichaud et al, 2014;Bokhart and Muddiman, 2016;Ekel€ of et al, 2018). For these experiments, due to the biological importance of rapid analysis, the samples were analyzed from the stage at atmospheric temperature, and a 2.94 mm mid-IR laser was used to desorb the material (Ekel€ of et al, 2018).…”

“…Samples were brought to the IR-MALDESI system, the principles and specificities of which have been enumerated in detail in previous reports (Robichaud et al, 2014;Bokhart and Muddiman, 2016;Ekel€ of et al, 2018). For these experiments, due to the biological importance of rapid analysis, the samples were analyzed from the stage at atmospheric temperature, and a 2.94 mm mid-IR laser was used to desorb the material (Ekel€ of et al, 2018). The desorbed neutral plant material was ionized in an orthogonal electrospray plume (50% methanol with 1 mM acetic acid at 2 ml/min for negative mode and 50% methanol with 0.2% formic acid at 2 ml/min for positive mode).…”

METASPACE: A community-populated knowledge base of spatial metabolomes in health and disease

“…We illustrated how METASPACE facilitates metabolite annotation for imaging MS, reveals the state of the art of the imaging MS technology, enables large-scale analysis of spatial metabolomes, and supports drug development. METASPACE, although not yet published, was already used in several publications [37][38][39][40][41][42][43] and highlighted in numerous reviews that indicates the significance and uniqueness of this resource for the imaging MS field. With the current rate of growth of 1000 datasets a year, its molecular and biological coverage will soon increase enough to provide spatial metabolomics atlases for various tissues, organs, and organisms.…”

IR-MALDESI mass spectrometry imaging of underivatized neurotransmitters in brain tissue of rats exposed to tetrabromobisphenol A

“…The imaging source and experimental procedures have been described in its recent configuration previously [28]. A mid-IR (2.94 μm) laser from JGMA Associates (Burlington, MA, USA) was used for laser sampling in all experiments [37]. Tissue regions of interest were imaged at 200 μm spatial resolution, with each mass spectrum generated from a single burst of 10 pulses of 100 μJ at 10 kHz.…”