Nanoscale Three-Dimensional Imaging of Drug Distributions in Single Cells via Laser Desorption Post-Ionization Mass Spectrometry

Abstract

Exploring the three-dimensional (3D) drug distribution within a single cell at nanoscale resolution with mass spectrometry imaging (MSI) techniques is crucial in cellular biology, yet it remains a great challenge due to limited lateral resolution, detection sensitivities, and reconstruction problems. Herein, a microlensed fiber laser desorption post-ionization time-of-flight mass spectrometer (MLF-LDPI-TOFMS) was developed for the 3D imaging of two anticancer drugs within single cells at a 500 × 500 × 500 nm3 voxel resolution. Nanoscale desorption was obtained with a microlensed fiber (MLF), and a 157 nm post-ionization laser was introduced to enhance the ionization yield. Furthermore, a new type of alignment method for 3D reconstruction was developed on the basis of our embedded uniform circular polystyrene microspheres (PMs). Our findings demonstrate that this 3D imaging technique has the potential to provide information about the 3D distributions of specific molecules at the nanoscale level.

Plasmonic Gold Nanoshell-Assisted Laser Desorption/Ionization Mass Spectrometry for Small-Biomolecule Analysis and Tissue Imaging

“…Mass spectrometry imaging (MSI) has emerged as a prevalent label-free technique that enables the spatial resolution of a large variety of analytes ranging from drugs, small biomolecules, and lipids to peptides and even proteins present in various complex samples, such as biological tissues and single cells. − Among the available techniques, matrix-assisted laser desorption/ionization (MALDI) has become one of the major techniques for MSI because of its excellent limit of detection (LOD), high salt tolerance, high throughput, and very small sample consumption since it was invented in the late 1980s. − Despite being widely adopted, the technique suffers from several inherent disadvantages that are associated with organic matrices, such as severe background interfering ions in the low mass region ( m / z < 700 Da), poor spot-to-spot reproducibility (i.e., “sweet spots”), and compromised ion yield toward small molecules in some cases. In addition, it remains a challenging issue to deposit a uniform layer of organic matrices onto tissue surfaces due to inhomogeneous and heterogeneous cocrystallization, resulting in deteriorated imaging resolution and potential image artifacts.…”

Nanometer Resolution Mass Spectro-Microtomography for In-Depth Anatomical Profiling of Single Cells

“…Compared to other laser-based MSI methods, the smaller diffraction limit (∼λ/2) of the VUV laser directly contributes to the improvement of spatial resolution. Moreover, since the ionization energy of most organic molecules is less than 10 eV, , the VUV laser has an appropriate photon energy (∼9.5 eV) to achieve high ionization efficiency. All in all, a single VUV laser pulse with suitable energy is sufficient to ablate the sample surface and obtain MS data with a good signal-to-noise ratio in situ .…”

Mapping Molecular Signatures in Plant Leaves, Flowers, and Fruits by a TiO2 Nanotube-Based Plasmonic Chip for Imprint Mass Spectrometry Imaging

“…Thus, this AuNP-hPDA-TDNT-based imprinting strategy will be introduced to other ambient ion sources (e.g., DESI, LA-ESI, and atmospheric MALDI) coupled to quadrupole-TOF or orbitrap for imprinting MSI analyses with higher molecular confidence. 18,63 Moreover, further efforts will be made to achieve plant single-cell MSI analysis with advanced near-field optics, 56,64,65 which is expected to decipher cell-specific synthesis and location in medicinal plants.…”

“…Of particular note, given that the potential interfering compounds that have the same nominal m/z value but varied retention time in chromatography and stem from different subregions of a plant might still exist. Thus, this AuNP-hPDA-TDNT-based imprinting strategy will be introduced to other ambient ion sources (e.g., DESI, LA-ESI, and atmospheric MALDI) coupled to quadrupole-TOF or orbitrap for imprinting MSI analyses with higher molecular confidence. , Moreover, further efforts will be made to achieve plant single-cell MSI analysis with advanced near-field optics, ,, which is expected to decipher cell-specific synthesis and location in medicinal plants.…”