東京薬科大学

Carbanions were widely regarded as unstable and highly reactive species. However, in fact, the first example of stable and isolable carbanion-containing salts was reported more than 120 years ago. Recent research of stable carbanions endowed a renewed context such as carbanionic “substituents” for tuning the physicochemical properties of organic materials. In addition, unique electronic and geometric structures of the anionic carbon atom enable to be used as ionic liquids, polymer materials, and electrolytes. This review summarises notable recent advances in stable carbanions, covering their synthetic methodologies, chemical bonding behaviour, coordination chemistry, and emerging applications. In particular, carbanions stabilised by cyano, fluorinated sulfonyl, and phosphonio groups are discussed.

We demonstrate that the refolding and activity recovery of aggregated proteins can be achieved simply and efficiently using two-phase systems of hydrophobic ionic liquids (ILs)/buffer. The high solubility of thermally aggregated concanavalin A (Con A) was observed in the hydrated tetra-n-octylammonium dihydrogen phosphate ([N8888][dhp]). Upon adding a buffer solution, the two-phase separation of the IL and buffer was confirmed, with the upper layer consisting of the IL phase and the lower layer consisting of the aqueous phase. Dissolved Con A was transferred to the buffer phase. Transfer efficiency of Con A into the buffer phase increased as the water content of the IL phase decreased, which was influenced by the buffer concentration and temperature. Con A transferred into the buffer phase exhibited a recovery of sugar chain-binding activity to levels comparable to that of native Con A.

Recently, α-mercuri-acetaldehyde (HgCH2CHO) and α-mercuri-acetic acid (HgCH2COOH) have been proposed as potential causative agents of Minamata disease. However, their toxicological profiles remain largely unknown. This study aimed to characterize the cytotoxicity, cellular uptake, and efflux mechanisms of these compounds in SH-SY5Y neuroblastoma cells and to compare these properties with those of methylmercury (MeHg). Cell viability was assessed after 24 hr of exposure to MeHg (1-10 µM), HgCH2CHO (10-50 µM), or HgCH2COOH (10-50 µM) using the CCK-8 assay. The roles of L-type amino acid transporter 1 (LAT1) and multidrug resistance-associated proteins (MRPs) were evaluated using the inhibitors JPH203 (1 µM) and MK571 (10 µM), respectively. Intracellular mercury accumulation was quantified after 24 hr of exposure to 3 µM of each compound using thermal decomposition-amalgamation atomic absorption spectrometry. All compounds exhibited dose-dependent cytotoxicity, with a relative toxicity order of MeHg (LC50: 6.4 µM) > HgCH2CHO (LC50: 14.6 µM) > HgCH2COOH (LC50: 39.2 µM). LAT1 inhibition had minimal effect on MeHg toxicity but slightly attenuated that of HgCH2CHO and HgCH2COOH. Conversely, MRP inhibition markedly enhanced MeHg toxicity, modestly increased that of HgCH2CHO, and slightly increased that of HgCH2COOH. Cellular mercury accumulation was consistent with cytotoxicity patterns, showing 10-20-fold lower levels for HgCH2CHO and HgCH2COOH than for MeHg. HgCH2CHO and HgCH2COOH were approximately 2-5-fold less cytotoxic than MeHg and exhibited substantially lower intracellular mercury levels. Our findings suggest that HgCH2CHO and HgCH2COOH are unlikely to have neurotoxic potential comparable to that of MeHg.

Sweat monitoring is gaining increasing attention as a key component of next-generation health technologies. In this study, we developed a compact and flexible wearable sensor based on microelectromechanical systems (MEMS) technology for real-time sweat rate measurement. The sensor detects thermal dissipation of a heat source due to sweat flow within a microchannel, allowing for non-invasive and continuous monitoring. It consists of a microheater and two temperature sensors placed symmetrically upstream and downstream along the microchannel wall. When sweat enters the channel, the convective flow causes a temperature difference between the two sensors, which varies according to the sweat rate. Numerical simulations using finite element analysis were conducted to optimize the sensor geometry, particularly the spacing between the heater and the temperature sensors. The device was fabricated by patterning Cr-Au electrodes onto a flexible polyimide substrate and forming a PDMS microchannel over the sensing area. During exercise experiments, the device was attached to the upper arm of a participant, and the sensor output was recorded wirelessly using a compact data acquisition system. The results showed a clear increase in sweat rate during exercise and a gradual decay during the post-exercise recovery phase. These results demonstrate that the developed device can reliably capture temporal changes in sweat rate, making it a promising candidate for wearable applications in personalized health monitoring and fitness tracking.

Small organisms such as water fleas and nematodes change their body stiffness in response to external stimuli and environmental alterations. Atomic force microscopy (AFM) is commonly used for stiffness measurement. However, the compression of the object by the cantilever is performed in the same direction as the observation, and this makes it difficult to observe the deformation of the object. Furthermore, the placement of the cantilever relative to the object is spatially quite limited and the driving distance is also very short: these limitations complicate measurements in organisms of various shapes and sizes. Here, we developed a new stiffness measurement technique using a cantilever attached to the tip of a micromanipulator, thereby overcoming these limitations of conventional AFM. During the compression of the object vertically downward, we observed the deformation from the side using a microscope tilted at 90°. The cantilever strain was monitored directly under the microscope rather than using the conventional optical reflection method. We used this approach to measure the stiffness of three small animal species, i.e., a tardigrade (Grevenius myrops), a nematode (Caenorhabditis elegans), and a water flea (Daphnia magna). We videotaped the compression of these organisms, and determined the strain distance of the object and cantilever from the images at different time points. A stress-strain curve was analyzed by plotting and Young's modulus was obtained as the curve's slope. Thus, Young's modulus data could be reliably obtained for varied organisms using the same device. This technology will facilitate measurements of stiffness of various small organisms.