Direct Conversion of Low-Concentration CO2 into N-Aryl and N-Alkyl Carbamic Acid Esters Using Tetramethyl Orthosilicate with Amidines as a CO2 Capture Agent and a Catalyst.

Herein, we report the direct conversion of low-concentration CO2 (15 vol %), equivalent to the CO2 concentration in the exhaust gas from a thermal power station, into carbamic acid esters (CAEs), which are precursors for pharmaceuticals, agrochemicals, and isocyanates. The reaction was performed using Si(OMe)4 as a nonmetallic regenerable reagent and 1,8-diazabicyclo[5.4.0]undec-7-ene as a CO2 capture agent and catalyst. This reaction system does not require the addition of metal complex catalysts or metal salt additives and is therefore simpler than our previously reported reaction system involving Ti(OR)4 and a Zn(II) catalyst. A variety of N-aryl, N-alkyl, and bis CAEs (precursors of polyurethane raw materials) were obtained in moderate to high yields (45-77% for 6 examples, 84-89% for 7 examples). In addition, bis CAEs were successfully synthesized from simulated exhaust gas containing impurities such as SO2, NO2, and CO or on a gram scale. We believe that this method can eliminate the use of toxic phosgene as the raw material for isocyanate production and mitigate CO2 emissions.

Affinity capillary electrophoresis with magnetic beads for multiplex quantitative analysis of bacterial 16S rRNA.

We have developed a novel method for microbial community analysis of bacterial 16S rRNAs based on affinity capillary electrophoresis using 16S rRNA-conjugated magnetic beads. We called this method magnetic beads affinity capillary electrophoresis (MB-ACE) which can be used for sequential and quantitative analysis of 16S rRNA. In this method, RNA extracted from a microbial community is biotin-modified and mixed with streptavidin-modified paramagnetic beads. This mixture is then injected into a capillary and localized in the middle of the capillary using a magnet held adjacent to the capillary. Subsequently, a fluorescent-labeled probe to detect the target 16S rRNA is injected into the capillary, and voltage is applied. The probe trapped on the RNA is dissociated by formamide and detected at its anodic end by measuring the fluorescence. Next, another fluorescent probe is injected, and thus the target 16S rRNA in the sample is quantified one by one. MB-ACE was used for the quantification of the 16S rRNAs of Escherichia coli and Pseudomonas putida in samples that were prepared by mixing RNA extracted from activated sludge and 16S rRNAs prepared by in vitro transcription. The two types of 16S rRNAs were quantified, indicating that MB-ACE can be used for sequential quantitative analysis of bacterial 16S rRNAs.

Affinity capillary electrophoresis with a DNA-nanoparticle conjugate as a new tool for genotyping.

We have developed a novel method for genotyping based on free solution affinity capillary electrophoresis. We prepared DNA-nanoparticle conjugates by mixing biotin-modified DNA and NeutrAvidin-modified polystyrene nanoparticles; this mixture was then injected into a capillary. Subsequently, we injected the fluorescent-labeled sample DNAs into the capillary, applied the voltage, increased its temperature after 7 min, and detected the fluorescence at its anodic end. This novel method was applied for genotyping human c-K-ras, and the three genotypes were definitely distinguishable with high reproducibility. This method can be easily automated, and it is useful for high-throughput gene mutation analysis.