Monostructured single-wall carbon nanotubes (SWCNTs) are important in both scientific research and electronic and biomedical applications; however, the bulk separation of SWCNTs into populations of single-chirality nanotubes remains challenging. Here we report a simple and effective method for the large-scale chirality separation of SWCNTs using a single-surfactant multicolumn gel chromatography method utilizing one surfactant and a series of vertically connected gel columns. This method is based on the structure-dependent interaction strength of SWCNTs with an allyl dextran-based gel. Overloading an SWCNT dispersion on the top column results in the adsorption sites of the column becoming fully occupied by the nanotubes that exhibit the strongest interaction with the gel. The unbound nanotubes flow through to the next column, and the nanotubes with the second strongest interaction with the gel are adsorbed in this stage. In this manner, 13 different (n, m) species were separated. Metallic SWCNTs were finally collected as unbound nanotubes because they exhibited the lowest interaction with the gel.

Endothelial dysfunction or activation elicited by oxidatively modified low-density lipoprotein (Ox-LDL) has been implicated in the pathogenesis of atherosclerosis, characterized by intimal thickening and lipid deposition in the arteries. Ox-LDL and its lipid constituents impair endothelial production of nitric oxide, and induce the endothelial expression of leukocyte adhesion molecules and smooth-muscle growth factors, which may be involved in atherogenesis. Vascular endothelial cells in culture and in vivo internalize and degrade Ox-LDL through a putative receptor-mediated pathway that does not involve macrophage scavenger receptors. Here we report the molecular cloning, using expression cloning strategy, of an Ox-LDL receptor from vascular endothelial cells. The cloned receptor is a membrane protein that belongs structurally to the C-type lectin family, and is expressed in vivo in vascular endothelium and vascular-rich organs.

Based on variation in nucleotide sequence within restricted regions in the putative C (core) gene of hepatitis C virus (HCV), four groups of HCV have been postulated in a panel of 44 HCV isolates. They were provisionally designated types I, II, III and IV. A method for typing HCV was developed, depending on the amplification of a C gene sequence by polymerase chain reaction using a universal primer (sense) and a mixture of four type-specific primers (antisense). HCV types were determined by the size of the products specific to each of them. Type II was found in HCV samples from 131 (82%) of 159 blood donors, more often than in those from 48 (60%) of 80 patients with non-A, non-B (NANB) liver disease in Japan (P< 0-01). In 11 haemophiliacs who had received imported coagulation factor concentrates, type I was found in five, as against type II in four. Double infection with two different HCV types was found in two patients with chronic NANB liver disease (types I and II; II and III) and two haemophiliacs (types I and II; I and III). HCV types were identical in mother and baby in each of two examples of perinatal transmission, and were also identical in donor and recipient in a case of accidental needle exposure.

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In Japan, fulminant hepatitis B is closely associated with HBV strains that do not produce HBeAg because of mutations in the precore region, which affect translation of HBeAg, or because of mutations in the core promoter, which affect transcription of the HBeAg coding region.

We have developed a novel separation method of metallic and semiconducting single-wall carbon nanotubes (SWCNTs) using agarose gel electrophoresis. When the SWCNTs were isolated with sodium dodecyl sulfate (SDS) and embedded in agarose gel, only the metallic SWCNTs separated from the starting gel by an electric field. After 20 min, almost all SWCNTs applied to gel electrophoresis were separated into two fractions, containing $95% semiconducting and $70% metallic nanotubes. The difference in the response to the electric field between metallic and semiconducting SWCNTs can be explained by the higher affinity of semiconducting SWCNTs to agarose than to SDS. # S ingle-wall carbon nanotubes (SWCNTs) have attracted a great deal of attention towards versatile applications, especially in the field of electronics, such as field effect transistors (FETs). 1,2) However, asproduced SWCNTs always contain both metallic and semiconducting SWCNTs, which is one of the most crucial problems preventing useful application of SWCNTs. There are several reports on the separation of metallic and semiconducting SWCNTs (MS separation) by dielectrophoresis, 3) amine extraction, 4) polymer wrapping, 5,6) selective oxidation, 7) and density-gradient ultracentrifugation; 8,9) however, problems in yield, purity, cost, etc. for industrial production of metallic and semiconducting SWCNTs are present in these methods. 10) Here, we report a novel separation method of metallic and semiconducting SWCNTs by agarose gel electrophoresis (AGE) that has high scalability for industrial application.Various SWCNTs synthesized by laser vaporization (LV1, 1:2 AE 0:1 nm in diameter; LV2, 1:4 AE 0:1 nm), high-pressure carbon monoxide processing (HiPco, R500, Carbon Nanotechnology, 1:0 AE 0:3 nm), and arc discharge (electric arc, APJ, Meijou Nano Carbon, 1:4 AE 0:1 nm) were used in this study. LV1 and LV2 SWCNTs were synthesized by conventional laser-oven technique and were highly purified as previously reported. 11) The growth temperatures were 1050 C for LV1-and 1250 C for LV2-SWCNTs. HiPco and arc SWCNTs were used without any purification steps. An SWCNT-dispersed solution was prepared as follows. SWCNTs were dispersed in 2% sodium dodecyl sulfate (SDS; 99%, Sigma-Aldrich) at 0.3 mg/ml and sonicated using a tip-type ultrasonic homogenizer (Taitec VP-30S) for 5.7 h at a duty cycle of 70% (total on-time: 4 h). In the case of arc SWCNTs, the sonication time was prolonged to 22.9 h (total on time: 16 h). The solution was centrifuged to remove bundles and impurities (16;100 Â g for 15 h at 25 C), and the resulting supernatant was collected as an SWCNT dispersion, where SWCNTs were coated with the surfactant.Agarose was chosen for the matrix of gel electrophoresis because agarose gel has been used for the separation of DNA which is almost the same size as SWCNTs. In the case of DNA, they are separated by a difference of length, where a network of the gel functions as a molecular sieve at the separation step and fixes the separated objects after the separation. 12) ...

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We have developed a novel method to separate metallic and semiconducting single-wall carbon nanotubes (SWCNTs) with high purities using agarose gel. When an SWCNTs/sodium dodecyl sulfate (SDS) dispersion was applied to a column containing agarose gel beads, semiconducting SWCNTs were trapped by the beads, while metallic SWCNTs passed through the column. After the semiconducting SWCNTs adsorbed to the beads were eluted with sodium deoxycholate solution, the column could be used for repeated separation. Because this continuous, repeatable separation method is applicable to a low-cost, large-scale process, it should enable the industrial production of metallic and semiconducting SWCNTs.