Mass Spectrometry and Cryogenic Electron Microscopy Illuminate Molecular-Level Mechanisms of the Oxidative and Structural Damage to Lipid Membranes by Radical-Bearing Graphene Oxide.

Biomedical applications of graphene in tumor and bacterial treatment have become cutting-edge fields due to its unique physical and chemical properties. However, a mechanistic understanding of the interactions and reactions between graphene-based material and biological systems such as lipid membranes remains elusive, especially at the molecular level. By using the unique field-induced droplet ionization mass spectrometry and cryogenic electron microscopy methodologies, we reveal the oxidation products of monolayer lipid membranes at the air-water interface and the change in the morphology of bilayer lipid membranes in an aqueous solution caused by the incorporation of graphene oxide bearing π-conjugated carbon radicals [hydrated graphene oxide (hGO)].

Investigation of the Acid-Mediated Photosensitized Reactions of Amphiphilic α-Keto Acids at the Air-Water Interface Using Field-Induced Droplet Ionization Mass Spectrometry.

The photochemistry of α-keto acids has been of great interest due to its implications in atmospheric and prebiotic chemistries. α-Keto acids with long alkyl chains are amphiphilic in nature, and they tend to partition at the air-water interface of atmospheric water droplets and add to the complexity of the chemistries therein. The air-water interface is a unique environment that plays a vital role in overall atmospheric processes.

Probe-Free Direct Identification of Type I and Type II Photosensitized Oxidation Using Field-Induced Droplet Ionization Mass Spectrometry.

While Type I and Type II photosensitizers are often carefully tailored to achieve their respective advantages in treating different cancers, the identifications of the Type I and II mechanisms as such, the key reaction intermediates, and the consequent oxidation products of the substrates have never been easy. Using our unique home-built field-induced droplet ionization mass spectrometry (FIDI-MS) method that selectively samples molecules at the air-water interface, here we show the facile determination of both Type I and II mechanisms of a poster-child photosensitizer, temoporfin, without the addition of any probes. The unstable doublet radical resulting from the hydrogen abstraction by the triplet temoporfin through the Type I mechanism is captured, manifesting the in situ advantage of FIDI-MS.

Beyond lipid peroxidation: Distinct mechanisms observed for POPC and POPG oxidation initiated by UV-enhanced Fenton reactions at the air-water interface.

Fenton or Fenton-like reactions are ubiquitous in nature, and the hydroxyl radicals (·OH) generated in these reactions are accountable for a plethora of oxidation processes both in the environment and in vivo. Among these oxidation reactions, lipid oxidation initiated by ·OH radicals has long been oversimplified as a peroxidation mechanism, but in reality, it is a highly complicated process that can result in a large variety of products. Using the unique field-induced droplet ionization mass spectrometry (FIDI-MS) methodology that is capable of selective sampling of amphiphilic molecules that reside at the air-water interface, here, we show distinct mechanisms from the ultraviolet (UV)-enhanced Fenton oxidations of two phospholipids, POPC and POPG, even though these two lipids possess the same functional groups that are vulnerable to ·OH attack.

Boron-Made N : Realization of a B≡B Triple Bond in the B Al Cluster.

Until now, all B≡B triple bonds have been achieved by adopting two ligands in the L→B≡B←L manner. Herein, we report an alternative route of designing the B≡B bonds based on the assumption that by acquiring two extra electrons, an element with the atomic number Z can have properties similar to those of the element with the atomic number Z+2. Specifically, we show that due to the electron donation from Al to B, the negatively charged B≡B kernel in the B Al cluster mimics a triple N≡N bond.

Mass Spectrometric Study of Acoustically Levitated Droplets Illuminates Molecular-Level Mechanism of Photodynamic Therapy for Cancer involving Lipid Oxidation.

Even though the general mechanism of photodynamic cancer therapy is known, the details and consequences of the reactions between the photosensitizer-generated singlet oxygen and substrate molecules remain elusive at the molecular level. Using temoporfin as the photosensitizer, here we combine field-induced droplet ionization mass spectrometry and acoustic levitation techniques to study the "wall-less" oxidation reactions of 18:1 cardiolipin and 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (POPG) mediated by singlet oxygen at the air-water interface of levitated water droplets. For both cardiolipin and POPG, every unsaturated oleyl chain is oxidized to an allyl hydroperoxide, which surprisingly is immune to further oxidation.

Intramolecular electron-induced proton transfer and its correlation with excited-state intramolecular proton transfer.

Electron-induced proton transfer depicts the proton motion coupled with the attachment of a low-energy electron to a molecule, which helps to understand copious fundamental chemical processes. Intramolecular electron-induced proton transfer is a similar process that occurs within a single molecule. To date, there is only one known intramolecular example, to the best of our knowledge.

Realization of an Al≡Al Triple Bond in the Gas-Phase Na Al Cluster via Double Electronic Transmutation.

The discovery of homodinuclear multiple bonds composed of Group 13 elements represents one of the most challenging frontiers in modern chemistry. A classical triple bond such as N≡N and HC≡CH contains one σ bond and two π bonds constructed from the p orbitals perpendicular to the σ bond. However, the traditional textbook triple bond between two Al atoms has remained elusive.

Low-Cost K Fe(CN) as a High-Voltage Cathode for Potassium-Ion Batteries.

Potassium-ion batteries (KIBs) are of interest for large-scale electrical energy storage, owing to the abundance of K resources and potential high energy density. Low-cost cathodes with high performance are crucial for KIBs. Herein, K Fe(CN) is shown to be a low-cost and high-voltage cathode for KIBs.

A Porous Network of Bismuth Used as the Anode Material for High-Energy-Density Potassium-Ion Batteries.

Potassium-ion batteries (KIBs) are plagued by a lack of materials for reversible accommodation of the large-sized K ion. Herein we present, the Bi anode in combination with the dimethoxyethane-(DME) based electrolyte to deliver a remarkable capacity of ca. 400 mAh g and long cycle stability with three distinct two-phase reactions of Bi↔ KBi ↔K Bi ↔K Bi.