One-Second Synthesis
A high-throughput DESI workflow uses charged microdroplets as reaction vessels, enabling synthesis and analysis at roughly one reaction per second.
A high-throughput DESI mass spectrometry system turns charged microdroplets into reaction vessels, allowing compounds to be synthesized and analyzed at roughly one reaction per second.
Developed by Graham Cooks’ group at Purdue University, the system arranges thousands of small reaction spots on high-density slides and uses a robotic arm to move samples between stages of the process. A charged solvent spray desorbs molecules directly from each spot for MS analysis, avoiding much of the cleaning and purification that slows conventional workflows.
“Mass spectrometry is conventionally viewed as a purely analytical tool, but we have been able to use it to not only rapidly screen materials but also to perform novel chemical reactions,” said Cooks in Purdue University’s press release. The platform switches between analysis and synthesis by changing the distance between the sample and instrument inlet, giving the charged droplets longer to travel and react before entering the mass spectrometer.
A study from earlier this year demonstrated the platform’s synthetic capability across six classes of nitrogen-, sulfur-, and oxygen-containing heterocycles. Transformations that can require heat, catalysts, added acid or base, and hours in bulk solution proceeded under ambient conditions within milliseconds. Tandem MS, NMR, and infrared spectroscopy confirmed the products, which generally required no further purification.
The automated screen extended that chemistry across hundreds of reaction combinations while using only small amounts of reagents, and the same microdroplet approach was adapted for site-selective peptide modification. Together, those demonstrations emphasized the platform’s ability to survey broader chemical space using less material and fewer processing steps.
“Our system requires fewer resources to do the same amount of work,” said Nicolás Morato. “Using microdroplet chemistry, we’ve eliminated the need for heat, catalysts, and other harsh conditions or materials.”
Chiral Mass Spec With a Twist
By combining spin and orbital angular momentum, femtosecond laser pulses improved gas-phase chiral discrimination by up to fourfold.
A new approach combines twisted laser beams with mass spectrometry to improve chiral discrimination by up to fourfold, without chemical derivatization or prior separation.
The researchers used femtosecond laser pulses carrying both spin angular momentum, associated with circular polarization, and orbital angular momentum, produced by a helical or “twisted” wavefront. The structured light ionized and fragmented the two enantiomers of camphor, with the resulting ions measured by time-of-flight mass spectrometry.
Circular polarization alone produced only weak differences between the enantiomers. When combined with orbital angular momentum, however, the contrast in total ion and fragment yields rose substantially, reaching values of around 0.4 under optimized conditions. Reversing the camphor enantiomer also reversed the direction of the ion-yield asymmetry, supporting the conclusion that the response reflected molecular handedness rather than an instrumental effect.
The degree of discrimination depended strongly on the laser conditions. Longer pulses produced a clearer chiral response than the shortest 25-femtosecond pulses, while increasing the laser intensity eventually reduced the contrast, consistent with saturation of the ionization process. Changing the orbital angular momentum charge from ±1 to ±2 also reversed the direction of the asymmetry, further linking the effect to the structure of the light.
The authors attribute the enhancement to interference between electric dipole and electric quadrupole interactions, with the combined spin and orbital properties of the beam creating a stronger enantioselective response than either alone. They describe the reversal observed between the two camphor enantiomers as “compelling evidence of the enantiospecificity of our method.”
While the approach remains an early demonstration using gas-phase camphor, it suggests that structured light could strengthen chiral mass spectrometry without requiring chiral reagents, derivatization, or prior separation.
Interactomics at Industrial Scale
HIP-MS combines ALFA-tagged bait expression, on-plate nanobody capture, and rapid LC-MS to scale interactome profiling to 9,200 pulldowns per week.
Affinity-enrichment mass spectrometry has long been constrained by labor-intensive sample preparation, large input requirements, and relatively slow LC-MS acquisition. A new workflow from Matthias Mann’s group at the Max Planck Institute of Biochemistry is designed to address all three bottlenecks at once.
High-throughput interactome profiling by mass spectrometry, or HIP-MS, combines transient expression of ALFA-tagged bait proteins with on-plate nanobody capture, automated washing, and direct tryptic digestion in 384-well plates. The system can prepare around 9,200 pulldowns per week, with LC-MS acquisition reaching up to 500 samples per day.
The gain in speed did not appear to come at the expense of the core biological signal. Across 25 bait proteins from different cellular compartments, interaction strengths measured with the 500-sample-per-day method closely matched those obtained with a fivefold longer gradient. The shorter method preserved the core interactome while producing fewer low-intensity, unannotated hits, giving a median precision of 60 percent across the benchmark panel.
Miniaturization also sharply reduced the amount of material required for each pulldown. The workflow recovered most of the endoplasmic reticulum membrane complex from only 10 micrograms of lysate and still detected core components at much lower inputs, cutting sample requirements by as much as 4,000-fold compared with recent large-scale interaction screens.
The team then applied HIP-MS to time-resolved biology, following endogenous TNFR1 signaling over minutes and mapping rapamycin-induced changes across several stages of autophagy. Together, those demonstrations suggest that HIP-MS offers more than faster interactome collection, allowing many baits, perturbations, and time points to be compared within the same experimental batch.
The findings are reported in a preprint and have not yet undergone peer review.
Narrowing the Native MS Envelope
Isotope depletion sharpens native mass spectra and improves top-down characterization without altering the structure of stable protein complexes.
Researchers at Maastricht University have reduced the spectral complexity of large proteins by depleting heavier carbon and nitrogen isotopes, improving mass measurement and top-down characterization without altering protein structure.
Led by Ron Heeren, the team expressed two Mycobacterium tuberculosis protein assemblies with increased proportions of carbon-12 and nitrogen-14. Native mass spectrometry of the EsxAB heterodimer and bacterioferritin B produced narrower isotope distributions and stronger monoisotopic peaks than the same proteins expressed at natural isotopic abundance.
For the smaller proteins, isotope depletion reduced the width of the isotope distributions by around 40 to 60 percent. Signal-to-noise at the monoisotopic peak increased across EsxA, EsxB, and EsxAB, while the bacterioferritin B monomer also showed a narrower envelope and stronger signal. The approach was then extended to an approximately 498-kilodalton, 24-subunit bacterioferritin complex, the largest isotope-depleted protein assembly yet examined under native conditions.
The cleaner spectra also improved native top-down analysis. High-energy collision dissociation increased sequence coverage from roughly 63 to 85 percent for EsxB and from 58 to 90 percent for bacterioferritin B, allowing more complete characterization of the intact proteins.
To test whether isotope depletion affected higher-order structure, the researchers compared natural-abundance and isotope-depleted bacterioferritin using single-particle cryo-electron microscopy. Both reconstructions reached 1.8-ångström resolution and showed near-identical atomic structures, with no measurable structural bias introduced by the isotope-depleted expression conditions.
The authors say further work should test whether the same structural compatibility holds for less stable or less symmetric protein complexes, while exploring the benefits of isotope depletion across larger native assemblies.
(Mass) Spectacular and Strange
A Game of Two Profiles
With the FIFA World Cup now underway, most attention is naturally focused on what happens on the pitch. A new study, however, shifts the analysis from passes and goals to blood and hormones, tracking how elite players’ steroid profiles respond to training.
Researchers measured 26 steroids in samples collected immediately before and after training from 27 elite male players at an Italian Serie A club. The targeted liquid chromatography-tandem mass spectrometry panel covered glucocorticoids, androgens, and related metabolites relevant to antidoping monitoring.
The response depended strongly on training load. High-load sessions produced the clearest increases in glucocorticoids and unconjugated androgens, while low-load training caused little acute change. The testosterone-to-androstenedione ratio also fell after moderate- and high-load sessions, and players reporting greater exertion showed larger cortisol-related responses.
The study’s immediate post-training sampling falls outside standard Athlete Biological Passport conditions, which require a delay after exercise. Nevertheless, the findings suggest that knowing how hard and how recently an athlete exercised could help put unexpected steroid changes into perspective.
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