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In order to realize the artificial photosynthetic devices splitting water to H2 and O2 (2H2O + hν → 2H2 + O2), it is desirable to utilize a wider wavelength range of light that extends to a lower energy region of solar spectrum. Here we report a triruthenium photosensitizer [Ru3(dmbpy)6(μ-HAT)]6+ (dmbpy = 4,4'-dimethyl-2,2'-bipyridine, HAT = 1,4,5,8,9,12-hexaazatriphenylene), which absorbs near-infrared light up to 800 nm based on its 1MLCT transition. Importantly, [Ru3(dmbpy)6(μ-HAT)]6+ is found to be the first example of a photosensitizer which can drive H2 evolution under the illumination of near-infrared light above 700 nm. The electrochemical and photochemical studies reveal that the reductive quenching within the ion-pair adducts of [Ru3(dmbpy)6(μ-HAT)]6+ and ascorbate anions affords a singly reduced form of [Ru3(dmbpy)6(μ-HAT)]6+, which is used as a reducing equivalent in the subsequent water reduction process.

This paper describes multiple ion-channel recordings through membrane proteins reconstituted in bilayer lipid membranes (BLMs) array. The BLMs array can be prepared by “Droplets Contacting Method” which forms BLMs at the interface of two lipid monolayers. Since this method does not require skilled techniques, it is highly reproducible and can be applied to automated system. We used a double well chip (DWC) for the droplets contacting method. We attempted to confine the BLMs forming areas with parylene micro-pore (parylene double well chip, PDWC) to augment the mechanical stability of BLMs. Subsequently, we arrayed the PDWC with electrodes for multiple recordings of channel proteins. We successfully demonstrated 14 channels simultaneous ion channel recordings through α-hemolysin.

This paper identifies the required configuration and orientation of α-glucosidase inhibitors, miglitol, α-1-C-butyl-DNJ, and α-1-C-butyl-LAB for binding to ntSI (isomaltase). Molecular dynamics (MD) calculations suggested that the flexibility around the keyhole of ntSI is lower than that of ctSI (sucrase). Furthermore, a molecular-docking study revealed that a specific binding orientation with a CH-π interaction (Trp370 and Phe648) is a requirement for achieving a strong affinity with ntSI. On the basis of these results, a new class of nortropane-type iminosugars, labystegines, hybrid iminosugars of LAB and calystegine, have been designed and synthesized efficiently from sugar-derived cyclic nitrones with intramolecular 1,3-dipolar cycloaddition or samarium iodide catalyzed reductive coupling reaction as the key step. Biological evaluation showed that our newly designed 3(S)-hydroxy labystegine (6a) inherited the selectivity against intestinal α-glucosidases from LAB, and its inhibition potency was 10 times better than that of miglitol. Labystegine, therefore, represents a promising new class of nortropane-type iminosugar for improving postprandial hyperglycemia.

© 2014 Elsevier Ltd. All rights reserved. We report the isolation and structural determination of fourteen iminosugars, containing five pyrrolizidines and five indolizidines, from Castanospermum australe. The structure of a new alkaloid was elucidated by spectroscopic methods as 6,8-diepi-castanospermine (13). Our side-by-side comparison between bicyclic and corresponding monocyclic iminosugars revealed that inhibition potency and spectrum against each enzyme are clearly changed by their core structures. Castanospermine (10) and 1-deoxynojirimycin (DNJ) have a common d-gluco configuration, and they showed the expected similar inhibition potency and spectrum. In sharp contrast, 6-epi-castanospermine (12) and 1-deoxymannojirimycin (manno-DNJ) both have the d-manno configuration but the α-mannosidase inhibition of 6-epi-castanospermine (12) was much better than that of manno-DNJ. 6,8-Diepi-castanospermine (13) could be regarded as a bicyclic derivative of talo-DNJ, but it showed a complete loss of α-galactosidase A inhibition. This behavior against α-galactosidase A is similar to that observed for 1-epi-australine (6) and altro-DMDP.

This paper describes a portable measurement system for current signals of an ion channel that is composed of a planar lipid bilayer. A stable and reproducible lipid bilayer is formed in outdoor environments by using a droplet contact method with a micropipette. Using this system, we demonstrated that the single-channel recording of a transmembrane protein (alpha-hemolysin) was achieved in the field at a high-altitude (∼3623 m). This system would be broadly applicable for obtaining environmental measurements using membrane proteins as a highly sensitive sensor.

This paper describes the rapid and repetitive formation of planar lipid bilayers via a mechanical droplet contact method for high-throughput ion channel analysis. In this method, first, an aqueous droplet delivered in a lipid-in-oil solution is mechanically divided into two small droplets. Second, the two small droplets contact each other, resulting in the lipid bilayer formation. Third, an ion channel is immediately reconstituted into the bilayer and the transmembrane current signals are measured. By repeating this procedure, massive data sets of the channel signals can be obtained. This method allowed us to perform statistical analysis of α-hemolysin conductance (n = 256 within 30 min) and channel inhibition experiments by contacting different types of the droplets in a short time frame.

Although ion channels are attractive targets for drug discovery, the systematic screening of ion channel-targeted drugs remains challenging. To facilitate automated single ion-channel recordings for the analysis of drug interactions with the intra- and extracellular domain, we have developed a parallel recording methodology using artificial cell membranes. The use of stable lipid bilayer formation in droplet chamber arrays facilitated automated, parallel, single-channel recording from reconstituted native and mutated ion channels. Using this system, several types of ion channels, including mutated forms, were characterised by determining the protein orientation. In addition, we provide evidence that both intra- and extracellular amyloid-beta fragments directly inhibit the channel open probability of the hBK channel. This automated methodology provides a high-throughput drug screening system for the targeting of ion channels and a data-intensive analysis technique for studying ion channel gating mechanisms.

This paper describes an investigation of drug effects for ion channels with recognizing the intra/extracellular directions. We have previously reported the ion channel recordings with bilayer lipid membranes (BLMs) which formed on a parylene micropore using droplets contact method. However, the low reconstitution probability of ion channels into BLMs has been a major issue. In this study, BLMs area and position are regulated with changing the numbers and positions of the parylene micropores. As a result, the simultaneous single channel recordings of K+ channel expressed in nerve system with BLM array were able to be achieved at the high probability.

This paper describes a method to form bilayer lipid membranes by splitting, sliding and contacting water droplets in oil containing lipid. A droplet surrounded by a lipid monolayer, which is easily formed by injecting an aqueous droplet into an organic solvent that contains lipids, is split and then, brought into contact each other. A bilayer lipid membrane is immediately formed at the interface of the split droplets. These processes are conducted on a micro device which we termed as split-and-contact device. The aqueous droplet with a lipid monolayer is split mechanically by either spinning or sliding motions of the device. We experimentally verified the effectiveness of the proposed split-and-contact device by using α-hemolysin and its blockers (single-stranded DNA and hepta-6-sulfato β-cyclodextrin). This device can be readily applicable to highly efficient biological sensor or drug discovery.

This paper describes a bilayer lipid membranes (BLMs) chip capable of solution exchange. In the previous report, we successfully reconstituted α-hemolysin (αHL) in BLMs using droplets contacting method with an array device. For drug screening, solution exchange is required to test the effect of inhibitors or promoters for proteins. In this study, we attempted to exchange the solution in a droplet using a microfluidic channel (Figure 1). We could successfully inject desired solution into the droplet forming BLMs and to withdraw the initial solution out of a droplet. The electrical signal of αHL with its some blockers which was injected later instead of the initial signal was successfully recorded. We consider that this method will enable more accurate and efficient drug screening system using artificially BLMs and reconstituted membrane protein.

This paper describes simultaneou us 16 channels ion-channel recordings through membrane proteins reconstituted in bilayer lipid membrannes (BLMs) as shown in Figure 1. Although multiple ion-channel recording is necessary for high-throughput screening (HTS) of drug [1], there are no reports of such systems as far as the authors are aware. We have developed several strategies to construct BLMs arrray for multiple ion-channel recording. The “droplets contacting method” which forms BLMs at the interface of two contacting droplets of lipid monolayers is one of the simplest and most efficient methods. Since it does not require skilled techniques, it is highly reproducible and can be applied to an automated system. [2]. In this study we particularly used a double well chip (DWC) (Figure 1a [3]) with parylene micro-pores in thedroplets contacting method. The parylene micro-pores confined the BLMs forming areas and subsequently, augmented the mechanical stability [4]. Using the droplets contacting method and parylene micro-pores, we succeeded in the multiple recording in 14 channels, which is the most multiple recording as far as we know. This method can be applied to fully automated membrane protein reconstitution for HTS system using a spotting robot [5].

This paper experimentally describes formation of lipid-coated droplet network and demonstrates a biological NAND logic gate using this network and DNA. Droplets which compose this network are comparted by bilayer lipid membranes (BLMs) and connected via biological nanopores of membrane proteins, which ssDNA passes through. In the geometry of the droplet network, four droplets were placed at the corners and the center of an equilateral triangle. Inputs corresponded to the DNA translocation via biological nanopores from the two droplets at the corners (#1 and 2 in Fig. 1) to the center (#3 in Fig. 1), which can be controlled by the applied electrical fields between the droplets. Output was determined by whether DNA translocation occurred through nanopores between the center (#3 in Fig. 1) and the other corner droplet (#4 in Fig. 1). We believe that this system enables direct connection between electrical systems and computing with biomolecules.

This paper describes microfluidic logic gates which use DNA and biological nanopores. Single-stranded DNA (ssDNA) can pass through αHL, a biological nanopore, incorporated in bilayer lipid membranes (BLMs), whereas double-stranded DNA (dsDNA) cannot. In this study, these passing and non-passing phenomena were applied as the binary system and logic gates. Two types of ssDNA were used as inputs, while the output was obtained by electrical signals across the nanopores, which recognizes whether ssDNA passed through the nanopores or not. NAND gate was successfully demonstrated by exploiting the mechanism. The proposed approach herein is significantly different from the conventional computation using DNA in the respect that electrical signals are directly obtained as the output, which drastically facilities the microfluidic system to connect to electrical systems for fast and accurate computing. In addition, it is not required to use fluorescence, enzyme or PCR in order to obtain outputs. We believe that this method leads to a rapid computing system using biomolecules.

This paper proposes a solution exchange of a droplet-based lipid bilayer system, in which the inner solution of a droplet is replaced for the purpose of efficient ion channel analyses. In our previous report, we successfully recorded the channel conductance of alpha-hemolysin in a bilayer lipid membrane using a droplet contact method that can create a spontaneous lipid bilayer at the interface of contacting droplets; this method is widely used as highly efficient method for preparing planar lipid membranes. When only pipetting droplets of the solution, this method is highly efficient for preparing lipid membranes. However, the drawback of droplet-based systems is their inability to exchange the solution within the droplets. To study the effect of inhibitors and promoters of ion channels in drug discovery, it would be beneficial to conduct a solution exchange of droplets to introduce membrane proteins and to apply or wash-out the chemicals. In this study, we propose a droplet contact method that allows for the solution exchange of droplets via microfluidic channels. We experimentally and numerically investigated the bilayer stability with respect to exchanging flow rates, and then demonstrated a binding assay of an alpha-hemolysin using one of its blockers. The solution exchange in this system was conducted in less than 20 s without rupturing the membrane. We believe that the proposed system will enhance the efficiency of ion channel analyses.