In-situ generation and global property profiling of metal nanoclusters by ultraviolet laser dissociation-mass spectrometry

Panda-UV Unlocks Deeper Protein Characterization with Internal Fragments in Ultraviolet Photodissociation Mass Spectrometry

Ultraviolet photodissociation (UVPD) mass spectrometry unlocks insights into the protein structure and sequence through fragmentation patterns. While N- and C-terminal fragments are traditionally relied upon, this work highlights the critical role of internal fragments in achieving near-complete sequencing of protein. Previous limitations of internal fragment utilization, owing to their abundance and potential for random matching, are addressed here with the development of Panda-UV, a novel software tool combining spectral calibration, and Pearson correlation coefficient scoring for confident fragment assignment. Panda-UV showcases its power through comprehensive benchmarks on three model proteins. The inclusion of internal fragments boosts identified fragment numbers by 26% and enhances average protein sequence coverage to a remarkable 93% for intact proteins, unlocking the hidden region of the largest protein carbonic anhydrase II in model proteins. Notably, an average of 65% of internal fragments can be identified in multiple replicates, demonstrating the high confidence of the fragments Panda-UV provided. Finally, the sequence coverages of mAb subunits can be increased up to 86% and the complementary determining regions (CDRs) are nearly completely sequenced in a single experiment. The source codes of Panda-UV are available at https://github.com/PHOENIXcenter/Panda-UV.

Molecular Structure Characterization of Micro/Nanoplastics by 193 nm Ultraviolet Photodissociation Mass Spectrometry

The degradation of macroplastics results in micro/nanoplastics (MNPs) in the natural environment, inducing high health risks worldwide. It remains challenging to characterize the accurate molecular structures of MNPs. Herein, we integrate 193 nm ultraviolet photodissociation (UVPD) with mass spectrometry to interrogate the molecular structures of poly(ethylene glycol) terephthalate and polyamide (PA) MNPs. The backbones of the MNP polymer can be efficiently dissociated by UVPD, producing rich types of fragment ions. Compared to high-energy collision dissociation (HCD), the structural informative fragment ions and corresponding sequence coverages obtained by UVPD were all improved 2.3 times on average, resulting in almost complete sequence coverage and precise structural interrogation of MNPs. We successfully determine the backbone connectivity differences of MNP analogues PA6, PA66, and PA610 by improving the average sequence coverage from 26.8% by HCD to 89.4% by UVPD. Our results highlight the potential of UVPD in characterizing and discriminating backbone connectivity and chain end structures of different types of MNPs.

Dynamic Metal Nanoclusters: A Review on Accurate Crystal Structures

Dynamic metal nanoclusters have garnered widespread attention due to their unique properties and potential applications in various fields. Researchers have been dedicated to developing new synthesis methods and strategies to control the morphologies, compositions, and structures of metal nanoclusters. Through optimized synthesis methods, it is possible to prepare clusters with precise sizes and shapes, providing a solid foundation for subsequent research. Accurate determination of their crystal structures is crucial for understanding their behavior and designing custom functional materials. Dynamic metal nanoclusters also demonstrate potential applications in catalysis and optoelectronics. By manipulating the sizes, compositions, and surface structures of the clusters, efficient catalysts and optoelectronic materials can be designed and synthesized for various chemical reactions and energy conversion processes. This review summarizes the research progress in the synthesis methods, crystal structure characterization, and potential applications of dynamic metal nanoclusters. Various nanoclusters composed of different metal elements are introduced, and their potential applications in catalysis, optics, electronics, and energy storage are discussed. Additionally, the important role of dynamic metal nanoclusters in materials science and nanotechnology is explored, along with an overview of the future directions and challenges in this field.

New Strategies on Green Synthesis of Dimethyl Carbonate from Carbon Dioxide and Methanol over Oxide Composites

Dimethyl carbonate is a generally used chemical substance which is environmentally sustainable in nature and used in a range of industrial applications as intermediate. Although various methods, including methanol phosgenation, transesterification and oxidative carbonylation of methanol, have been developed for large-scale industrial production of DMC, they are expensive, unsafe and use noxious raw materials. Green production of DMC from CO2 and methanol is the most appropriate and eco-friendly method. Numerous catalysts were studied and tested in this regard. The issues of low yield and difficulty in tests have not been resolved fundamentally, which is caused by the inherent problems of the synthetic pathway and limitations imposed by thermodynamics. Electron-assisted activation of CO2 and membrane reactors which can separate products in real-time giving a maximum yield of DMC are also being used in the quest to find more effective production method. In this review paper, we deeply addressed green production methods of DMC using Zr/Ce/Cu-based nanocomposites as catalysts. Moreover, the relationship between the structure and activity of catalysts, catalytic mechanisms, molecular activation and active sites identification of catalysts are also discussed.

Silver Nanostructured Substrates in LDI-MS of Low Molecular Weight Compounds

Mass spectrometric techniques can provide data on the composition of a studied sample, utilizing both targeted and untargeted approaches to solve various research problems. Analysis of compounds in the low mass range has practical implications in many areas of research and industry. Laser desorption ionization techniques are utilized for the analysis of molecules in a low mass region using low sample volume, providing high sensitivity with low chemical background. The fabrication of substrates based on nanostructures to assist ionization with well-controlled morphology may improve LDI-MS efficiency for silver nanoparticles with plasmonic properties. In this work, we report an approach for the preparation of silver nanostructured substrates applied as laser desorption ionization (LDI) plates, using the chemical vapor deposition (CVD) technique. Depending on the mass of used CVD precursor, the approach allowed the synthesis of LDI plates with tunable sensitivity for various low molecular weight compounds in both ion-positive and ion-negative modes. Reduced chemical background and sensitivity to small biomolecules of various classes (fatty acids, amino acids and water-soluble metabolites) at nanomolar and picomolar detection levels for lipids such as triacylglycerols, phosphatidylethanolamines and lyso-phosphatidylcholines represent an emerging perspective for applications of LDI-MS plates for the collection of molecular profiles and targeted analysis of low molecular weight compounds for various purposes.