Water-Dispersible Carbon Nano-Test Tubes as a Container for Concentrated DNA Molecules.

Invited for the cover of this issue are Takashi Kyotani, Tetsuji Itoh and co-workers at Tohoku University, Gunma University and AIST. The image depicts the synthesis of water-dispersible carbon nano-test tubes by using a template technique and the selective adsorption of DNA into the inner space of these test tubes. Read the full text of the article at 10.1002/chem.202301422.

Water-Dispersible Carbon Nano-Test Tubes as a Container for Concentrated DNA Molecules.

Water-dispersible carbon nano-test tubes (CNTTs) with an inner and outer diameter of about 25 and 35 nm, respectively, were prepared by the template technique and then their inner carbon surface was selectively oxidized to introduce carboxy groups. The adsorption behavior of DNA molecules on the oxidized CNTTs (Ox-CNTTs) was examined in the presence of Ca2+ cations. Many DNA molecules are attracted to the inner space of Ox-CNTTs based on the Ca2+ -mediated electrostatic interaction between DNA phosphate groups and carboxylate anions on the inner carbon surface. Moreover, the total net charge of the DNA adsorbed was found to be equal to the total charge of the carboxylate anions. This selective adsorption into the interior of Ox-CNTTs can be explained from the fact that the electrostatic interaction onto the inner concave surface is much stronger than that on the outer convex surface. On the other hand, the desorption of DNA easily occurs whenever Ca2+ cations are removed by washing with deionized water. Thus, each of Ox-CNTTs works well as a nano-container for a large amount of DNA molecules, thereby resulting in the occurrence of DNA enrichment in the nanospace.

Orientation Control of Trametes Laccases on a Carbon Electrode Surface to Understand the Orientation Effect on the Electrocatalytic Activity.

By using a carbon-coated anodic aluminum oxide (CAAO) film as a monolithic porous electrode for the immobilization of Trametes laccases (LACs), an attempt is made to control the orientation of LAC molecules toward the electrode surface simply by applying an electric potential to the CAAO film. Because the resulting film is characterized by a myriad of open, simple, and straight nanochannels with diameters as large as 40 nm, the O2 diffusion problem in pores is minimized, thereby making it possible to highlight the effect of such orientation on the electrocatalytic activity as a biocathode. It has been evidenced that LAC molecules are favorably oriented for a smooth electron transfer from the electrode when the LACs are immobilized with applying a positive voltage to the electrode, and such favorable orientation exhibits 3.7-times higher electrocatalytic activity than unfavorable orientation. Furthermore, the orientation mechanism has been rationally explained in terms of local surface chemistry on a LAC molecule.

Real Understanding of the Nitrogen-Doping Effect on the Electrochemical Performance of Carbon Materials by Using Carbon-Coated Mesoporous Silica as a Model Material.

The main aim of the present work is to precisely understand the sole effect of nitrogen doping on the electrochemical performance of porous carbon materials. To achieve this objective, the whole surface of mesoporous silica (SBA-15) was coated with a thin layer of carbon (about 0.4 nm) with and without N-doping by using acetonitrile and acetylene chemical vapor deposition, respectively. The resulting N-doped and nondoped carbon-coated silica samples have mesopore structures identical to those in the original SBA-15, and they are practically the same in terms of not only the pore size and pore structure but also the particle size distribution and particle morphology, with the exception of N-doping, which makes them unique model materials to extract the sole effect of nitrogen on the performances of electrochemical capacitors and electrocatalytic oxygen reduction. Moreover, the outstanding features of the carbon-coated silica samples allow even a quantitative understanding of the pseudocapacitance induced by nitrogen functionalities on the carbon surface in an acidic aqueous electrolyte.

Tim4 recognizes carbon nanotubes and mediates phagocytosis leading to granuloma formation.

Macrophage recognition and phagocytosis of crystals is critical for the associated fibrosis and cancer. Of note, multi-walled carbon nanotubes (MWCNTs), the highly representative products of nanotechnology, induce macrophage NLRP3 inflammasome activation and cause asbestosis-like pathogenesis. However, it remains largely unknown how macrophages efficiently recognize MWCNTs on their cell surfaces. Here, we identify by a targeted screening of phagocyte receptors the phosphatidylserine receptors T cell immunoglobulin mucin 4 (Tim4) and Tim1 as the pattern-recognition receptors for carbon crystals. Docking simulation studies reveal spatiotemporally stable interfaces between aromatic residues in the extracellular IgV domain of Tim4 and one-dimensional carbon crystals. Further, CRISPR-Cas9-mediated deletion of Tim4 and Tim1 reveals that Tim4, but not Tim1, critically contributes to the recognition of MWCNTs by peritoneal macrophages and to granuloma development in a mouse model of direct mesothelium exposure to MWCNTs. These results suggest that Tim4 recognizes MWCNTs through aromatic interactions and mediates phagocytosis leading to granulomas.

Size-Dependent Filling Behavior of UV-Curable Di(meth)acrylate Resins into Carbon-Coated Anodic Aluminum Oxide Pores of around 20 nm.

Ultraviolet (UV) nanoimprint lithography is a promising nanofabrication technology with cost efficiency and high throughput for sub-20 nm size semiconductor, data storage, and optical devices. To test formability of organic resist mask patterns, we investigated whether the type of polymerizable di(meth)acrylate monomer affected the fabrication of cured resin nanopillars by UV nanoimprinting using molds with pores of around 20 nm. We used carbon-coated, porous, anodic aluminum oxide (AAO) films prepared by electrochemical oxidation and thermal chemical vapor deposition as molds, because the pore diameter distribution in the range of 10-40 nm was suitable for combinatorial testing to investigate whether UV-curable resins comprising each monomer were filled into the mold recesses in UV nanoimprinting. Although the UV-curable resins, except for a bisphenol A-based one, detached from the molds without pull-out defects after radical photopolymerization under UV light, the number of cured resin nanopillars was independent of the viscosity of the monomer(s) in each resin. The number of resin nanopillars increased and their diameter decreased as the number of hydroxy groups in the aliphatic diacrylate monomers increased. It was concluded that the filling of the carbon-coated pores having diameters of around 20 nm with UV-curable resins was promoted by the presence of hydroxy groups in the aliphatic di(meth)acrylate monomers.

Blood compatibility and tissue responsiveness on simple and durable methylsiloxane coating.

This study was conducted to evaluate the blood compatibility and tissue responsiveness of methylsiloxane (MS)-coated inorganic (glass and metal) substrates both in vitro and in vivo. MS was prepared from methyltriethoxysilane (MTES) through hydrolysis of a sol-gel solution at 80 °C. The adhesive strength of the MS coating was evaluated by using a tear-off test, revealing that the MS strongly adhered to the surface of the inorganic substrates. Blood compatibility was evaluated by assessing platelet adhesion and blood plasma coagulation time. The platelet aggregation ratio of the MS-coated glass tube was reduced to 10%, which was much smaller than that of the coating-free glass tubes (99%) and conventional blood-compatible polystyrene (PS) tubes (18%). Coagulation time was measured by active partial thromboplastin time (APTT) test, which showed that MS coating is as inert as PS in activating blood coagulation factor XII. Tissue responsiveness to the bulk MS sample, evaluated by animal test, showed a desirable compatibility comparable to that of the control titanium sample. This study indicated that MS coating is readily available to convert inorganic materials to useful biomaterials that have suitable mechanical strength and are compatible with blood and tissue.

Bioactive titanate nanomesh layer on the Ti-based bulk metallic glass by hydrothermal-electrochemical technique.

Titanate nanomesh layers were fabricated on Ti-based bulk metallic glass (BMG) to induce bioactivity in the form of apatite-forming ability. Titanate nanomesh layers were prepared by hydrothermal-electrochemical treatment at 90 degrees C for 2 h, with an aqueous solution of NaOH as an electrolyte. A constant electric current of 0.5 mA cm(-2) was applied between the BMG substrate and a Pt electrode acting as the anode and cathode, respectively. A nanomesh layer, consisting of nanowires (approximately 20 nm in diameter) formed on the BMG. An immersion test in simulated body fluid for 12 days revealed that the titanate nanomesh layer on the BMG promoted the growth of bone-like hydroxyapatite.