Next-Generation Infrared Matrix-Assisted Laser Desorption Electrospray Ionization Source for Mass Spectrometry Imaging and High-Throughput Screening

Abstract

Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) is a hybrid, ambient ionization source that combines the advantages of electrospray ionization and matrix-assisted laser desorption/ionization, making it a versatile tool for both highthroughput screening (HTS) and mass spectrometry imaging (MSI) studies. To expand the capabilities of the IR-MALDESI source, an entirely new architecture was designed to overcome the key limitations of the previous source. This next-generation (NextGen) IR-MALDESI source features a vertically mounted IR-laser, a planar translation stage with computerized sample height control, an aluminum enclosure, and a novel mass spectrometer interface plate. The NextGen IR-MALDESI source has improved user-friendliness, improved overall versatility, and can be coupled to numerous Orbitrap mass spectrometers to accommodate more research laboratories. In this work, we highlight the benefits of the NextGen IR-MALDESI source as an improved platform for MSI and direct analysis. We also optimize the NextGen MALDESI source component geometries to increase target ion abundances over a wide m/z range. Finally, documentation is provided for each NextGen IR-MALDESI part so that it can be replicated and incorporated into any lab space.

Improved spatial resolution of infrared matrix‐assisted laser desorption electrospray ionization mass spectrometry imaging using a reflective objective

“…The IR‐MALDESI source has previously been described in great detail 12,13 . This work was completed on the novel NextGen IR‐MALDESI source coupled to an Orbitrap Exploris 240 (Thermo Fisher Scientific) 27 . A key design element of the IR‐MALDESI source is a vertically‐mounted JGMA 2970 nm mid‐IR laser (JGM Associates, Inc.) that allows for higher laser energy efficiency.…”

“… 12 , 13 This work was completed on the novel NextGen IR‐MALDESI source coupled to an Orbitrap Exploris 240 (Thermo Fisher Scientific). 27 A key design element of the IR‐MALDESI source is a vertically‐mounted JGMA 2970 nm mid‐IR laser (JGM Associates, Inc.) that allows for higher laser energy efficiency. A down tube contains a beam expander system composed of two CaF 2 lenses ( f = −75 mm and +250 mm).…”

Developing transmission mode for infrared matrix‐assisted laser desorption electrospray ionization mass spectrometry imaging

“…Preliminary tm‐IR‐MALDESI experiments included stilts constructed from molded plastic building blocks (data not shown). The present work focuses on tm‐IR‐MALDESI performed on the novel NextGen source 13 . A transmission mode slide holder was customized for the NextGen source in the Precision Engineering Consortium at North Carolina State University.…”

“…The present work focuses on tm-IR-MALDESI performed on the novel NextGen source. 13 A transmission mode slide holder was customized for the NextGen source in the Precision Engineering Consortium at North Carolina State University. An aluminum block was cut to shape a single arm that extends past the sample stage and above the MS inlet.…”

Transforming a Mid-infrared Laser Profile from Gaussian to a Top-Hat with a Diffractive Optical Element for Mass Spectrometry Imaging

“…The customized IR-MALDESI source, named Next-Gen IR-MALDESI, was coupled to an Exploris 240 (Thermo Fisher Scientific, Bremen, Germany) for all the experiments presented here. 22 The optical train described above is used to deliver and focus the laser beam on the sample surface for ablation, and the ablated plume is then postionized by orthogonal electrospray. Samples are placed on a 3D-translation stage (Newport, Irvine, CA, USA) with an embedded Peltier cooler component (TE Technology, Traverse City, MI, USA).…”