Corrigendum to "Advancing mass spectrometry-based chemical imaging: A noncontact continuous flow surface probe in mass spectrometry for enhanced signal detection and spatial resolution" [Talanta 273 (2024) 125858].

In the statement "This innovative MS imaging system can be directly applied to real tissue systems and other plant samples to visualize the molecular level distributions." "innovative" should be read as "important".

Advancing mass spectrometry-based chemical imaging: A noncontact continuous flow surface probe in mass spectrometry for enhanced signal detection and spatial resolution.

A new method has been developed for mass spectrometric imaging of small molecules and proteins on tissue or in thinly sliced materials. A laser desorption Venturi electrospray ionization-mass spectrometer was developed for molecular imaging. This method combines laser desorption (LD) and electrospray ionization (ESI) systems before a mass spectrometer (MS).

High-performance peptide and disulfide mapping by direct injection of intact proteins using on-line coupled UV-liquid chromatography microdroplet mass spectrometry (UVLC-MMS).

Microdroplet mass spectrometry (MMS), achieving ultra-fast enzyme digestion in the ionization source, holds great promises for innovating protein analysis. Here, in-depth protein characterization is demonstrated by direct injection of intact protein mixtures via on-line coupling MMS with capillary C4 liquid chromatography (LC) containing UV windows (UVLC-MMS) through an enzyme introduction tee. We showed complete sets of peptides of individual proteins (hemoglobin, bovine serum albumin, and ribonuclease A) in a mixture could be obtained in one injection.

Simultaneous detection of positively and negatively charged microparticles by ion trap mass spectrometry.

This study describes the simultaneous detection of positively and negatively charged microparticles by ion trap mass spectrometry (IT-MS) as a novel analytical measurement technique. The instrument was configured with a feeding capillary for particle introduction, an ion trap, and a charge detector that responds to both ions simultaneously. Positively and negatively charged particles are generated by the triboelectric effect inside the capillary entrance of the instrument.

Revisiting Disulfide-Yne and Disulfide-Diazonium Reactions for Potential Direct Modification of Disulfide Bonds in Proteins.

To find their potential use in protein research, direct addition of a disulfide compound to alkyne (namely disulfide-yne reaction) and S-arylation with arenediazonium salt (namely disulfide-diazonium reaction) were investigated in aqueous or protic solutions. The reaction of dimethyl disulfide with 5-hexynol performed best under 300 nm irradiation in the presence of sodium acetate to afford 5,6-bis(methylthio)-5-hexenol in 60% yield. Without the prior reduction of a disulfide bond to thiols, the disulfide-yne reactions have the advantage of 100% atom economy.

Harnessing natural-product-inspired combinatorial chemistry and computation-guided synthesis to develop -glycan modulators as anticancer agents.

Modulation of -glycosylation using human Golgi α-mannosidase II (α-hGMII) inhibitors is a potential anticancer approach, but the clinical utility of current α-hGMII inhibitors is limited by their co-inhibition of human lysosomal α-mannosidase (α-hLM), resulting in abnormal storage of oligomannoses. We describe the synthesis and screening of a small library of novel bicyclic iminosugar-based scaffolds, prepared natural product-inspired combinatorial chemistry (NPICC), which resulted in the identification of a primary α-hGMII inhibitor with 13.5-fold selectivity over α-hLM.

Portable particle mass spectrometer.

Particle pollutants in air have been confirmed to damage human health. The PM10 concentration is an important parameter for air quality determination. In this study, a portable quadrupole ion trap mass spectrometer (QIT-MS) was developed and used to quantitate microparticles and particulate standards.

Nanodiamond Solid-Phase Extraction and Triton X-114 Cloud Point Separation for Robust Fractionation and Shotgun Proteomics Analysis of the Human Serum Proteome.

Human serum is one of the most attractive specimens in biomarker research. However, its overcomplicated properties have hindered the analysis of low-abundance proteins by conventional mass spectrometry techniques. This work proposes an innovative strategy for utilizing nanodiamonds (NDs) in combination with Triton X-114 protein extraction to fractionate the crude serum to six pH-tuned fractions, simplifying the overall proteome and facilitating protein profiling with high efficiency.

Development of a focused high-energy macromolecular ion beam.

In this work, we report the development of a focused macromolecular ion beam with kinetic energy of up to 110 keV. The system consists of a quadrupole ion trap (QIT), einzel lens and linear accelerator (LINAC). Based on the combination of matrix-assisted laser desorption ionization (MALDI) and quadrupole ion trapping (QIT), ions were desorbed from the surface and trapped with an ion trap to form biomolecular ion packets.

Comprehensive Workflow for Mapping Disulfide Linkages Including Free Thiols and Error Checking by On-Line UV-Induced Precolumn Reduction and Spiked Control.

Mapping highly complicated disulfide linkages and free thiols via liquid chromatography-tandem mass spectrometry (LC-MS) is challenging because of the difficulties in optimizing sample preparation to acquire critical MS data and detecting mispairings. Herein, we report a highly efficient and comprehensive workflow using an on-line UV-induced precolumn reduction tandem mass spectrometry (UV-LC-MS) coupled with two-stage data analysis and spiked control. UV-LC-MS features a gradient run of acetonitrile containing a tunable percentage of photoinitiators (acetone/alcohol) that drives the sample to the MS through a UV-flow cell and reverse phase column to separate UV-induced products for subsequent fragmentation via low energy collision-induced dissociation.

Enhancement of fucosylated N-glycan isomer separation with an ultrahigh column temperature in porous graphitic carbon liquid chromatography-mass spectrometry.

Due to the heterogeneous and isomeric nature of glycans, the development of an advanced separation of distinct glycan isomers is essential for glycan research and application. In this study, we utilized porous graphite carbon (PGC) chromatography for the separation of isomeric oligosaccharides without reduction or chemical derivatization at 190 °C in a custom-built heating oven. Furthermore, the fine structures of glycan isomers could be identified by using ultrahigh temperature PGC liquid chromatography mass spectrometry (UHT-PGC-LCMS).

A portable multiple ionization source biological mass spectrometer.

In the past, matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI), used for large biomolecule detection, were usually installed in two separate mass spectrometers. In this study, they were equipped in the same mass spectrometer. This portable biological mass spectrometer has multiple ionization capabilities in the same mass spectrometer and shares the same mass analyzer and detector.

A quadrupole ion trap mass spectrometer for dry microparticle analysis.

In this work, we report a new design of a charge detection quadrupole ion trap mass spectrometer (QIT-MS) for the analysis of micro-sized dry inorganic and bioparticles including red blood cells (RBCs) and different sizes of MCF-7 breast cancer cells. The developed method is one of the fastest methods to measure the mass of micro-sized particles. This system allows the online analysis of various micro-sized particles up to 1 × 10 Da.

Biomolecular Clusters Distribution up to Mega Dalton Region Using MALDI-Quadrupole Ion Trap Mass Spectrometer.

We present the first report on complete cluster distributions of cytochrome c (molecular weight of 12.4 kDa) and bovine serum albumin ((BSA), molecular weight of 66.4 kDa) with mass-to-charge ratio (/) reaching 350,000 and 1,400,000, respectively, by matrix-assisted laser desorption/ionization (MALDI).

ESI-MS measurements for the equilibrium constants of copper(II)-insulin complexes.

Trace elements regulate many biological reactions in the body. Copper(II) is known as one of trace elements and capable of binding to proteins. Insulin is a blood glucose-lowering peptide hormone and it is secreted by the pancreatic β-cells.

ESI MS for Microsized Bioparticles.

An ESI ion trap mass spectrometer was designed for high-throughput and rapid mass analysis of large bioparticles. Mass calibration of the instrument was performed using commercially available polystyrene (PS) microparticles with a size comparable to cancer cells. Different sizes of MCF-7 breast cancer cells (8 to 15 μm) were used in this study.

Substrate Preference and Interplay of Fucosyltransferase 8 and N-Acetylglucosaminyltransferases.

The core fucosylation of N-glycans on glycoproteins is catalyzed by fucosyltransferase 8 (FUT8) in mammalian cells and is involved in various biological functions, such as protein function, cancer progression, and postnatal development. The substrate specificity of FUT8 toward bi-antennary N-glycans has been reported, but it is unclear with regard to tri-antennary and tetra-antennary glycans. Here, we examined the specificity and activity of human FUT8 toward tri- and tetra-antennary N-glycans in the forms of glycopeptides.

Quantifying Na(I)-insulin and K(I)-insulin non-covalent complexes by ESI-MS method and calculation of their equilibrium constants.

In this study, the dissociation and formation equilibrium constants of Na(I)-insulin and K(I)-insulin complexes have been calculated after the quantifying them on ESI mass spectrometer. The ESI-MS spectra of the complexes were measured by using the solvents as 50% MeOH in water and 100% water. The effect of pH on the Na(I)-insulin and K(I)-insulin complex formation were examined.

Macromolecular ion accelerator mass spectrometer.

We present a newly developed macromolecular ion accelerator mass spectrometer that combines a dual-ion-trap device and a macromolecular ion accelerator (MIA) to achieve the capability of analyzing samples with a mixture of large biomolecules. MIA greatly increases detection efficiency. The dual ion trap includes a quadrupole ion trap (QIT) and a linear ion trap (LIT) in tandem.

Kelvin spray ionization.

A novel self-powered dual spray ionization source has been developed for applications in mass spectrometry. This new source does not use any power supply and produces both positive and negative ions simultaneously. The idea behind this ionization source comes from the Kelvin water dropper.

Biomolecular dual-ion-trap mass analyzer.

We developed the first dual-ion-trap mass analyzer which can detect ions with a high mass-to-charge ratio (m/z > 6000). The first ion trap is a quadrupole ion trap (QIT), which was operated by step scanning of the trapping frequency for a sample containing mixtures of biomolecules. The second ion trap, linear ion trap (LIT), was utilized to capture selected ions ejected out of the QIT so that all ions from the QIT can be examined one by one.