Method for Quantification of Ribonucleotides and Deoxyribonucleotides in Human Cells Using (Trimethylsilyl)diazomethane Derivatization Followed by Liquid Chromatography-Tandem Mass Spectrometry.

Investigation into intracellular ribonucleotides (RNs) and deoxyribonucleotides (dRNs) is important for studies of the mechanism of many biological processes, such as RNA and DNA synthesis and DNA repair, as well as metabolic and therapeutic efficacy of nucleoside analogues. However, current methods are still unsatisfactory for determination of nucleotides in complex matrixes. Here we describe a novel method for the determination of RN and dRN pools in cells based on fast derivatization with (trimethylsilyl)diazomethane (TMSD) followed by quantification using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Derivatization was accomplished in 3 min, and each derivatized nucleotide not only had a sufficient retention on reversed-phase column by introduction of methyl groups but also exhibited a unique ion transition which consequently eliminated mutual interference in LC-MS/MS. Chromatographic separation was performed on a C18 column with a simple acetonitrile-water gradient elution system, which avoided contamination and ion suppression caused by ion-pairing reagents. The developed method was fully validated and applied to the analysis of RNs and dRNs in cell samples. Moreover, results demonstrated that the applicability of this method could be extended to nucleoside analogues and their metabolites and could facilitate many applications in future studies.

Anodic SnO2 porous nanostructures with rich grain boundaries for efficient CO2 electroreduction to formate.

Formic acid (HCOOH), the acidic form of formate, is an important hydrogen carrier which can be directly used in fuel cells. Development of earth-abundant element-based catalysts to convert carbon dioxide (CO2) into HCOOH or formate with high selectivity and high efficiency has been a vigorous research activity in recent years but remains an unsolved challenge. In this contribution, using one-step anodization, we prepare nanotubular SnO2 porous nanostructures with high surface area (90.1 m2 g-1), large porosity (0.74 cm3 g-1), and rich grain boundaries for electrochemical CO2 reduction (CO2RR). They exhibit stable 95% faradaic efficiency (FE) towards CO2RR and 73% FE for formate at -0.8 VRHE. The notable performance of such SnO2 nanostructures can be attributed to their unique structural and chemical properties, which provide active sites for CO2 adsorption and conversion, and easy access for CO2 to the active sites. The insights gained from the structure/property relationships might be beneficial for designing superior electrocatalysts for CO2 electroreduction into formate.

Assembling Highly Coordinated Pt Sites on Nanoporous Gold for Efficient Oxygen Electroreduction.

Pt with high coordination number (HCN) located in the defect surface sites is favorable for high oxygen reduction reaction activity. However, it is still a challenge to design and fabricate such a structure with a high density of Pt HCN sites at minimum Pt usage. Here, using nanoporous Au (NPG) that intrinsically possesses a higher proportion of HCN Au atoms over traditional nanoparticles, we epitaxially deposit Pt monolayer onto NPG to inherit the high-density HCN Pt sites. Among the NPG-Pt catalysts, the one with a smaller ligament size possesses a higher proportion of HCN Pt atoms, thus exhibiting a 5.2-fold specific activity and 18.7-fold mass activity enhancement than the commercial Pt/C catalyst. Moreover, depositing Au atoms on the NPG-Pt surface can further increase the HCN Pt surface exposure, which leads to a 6.9-fold specific activity and 19.1-fold mass activity increase as compared to Pt/C.

Atomic origins of high electrochemical CO2 reduction efficiency on nanoporous gold.

First principles calculations show that gold atoms with low generalized coordination numbers possess high activity for electroreduction of CO2 to CO. Atom-resolved three-dimensional reconstruction reveals that dealloyed nanoporous gold possesses such a favourable structure characteristic, which results in a faradaic efficiency as high as 94% for CO production.