Biocompatible and optically stable hydrophobic fluorescent carbon dots for isolation and imaging of lipid rafts in model membrane

Lateral heterogeneity in cell membranes features a variety of compositions that influence their inherent properties. One such biophysical variation is the formation of a membrane or lipid raft, which plays important roles in many cellular processes. The lipid rafts on the cell membrane are mostly identified by specific dyes and heavy metal quantum dots, which have their own drawbacks, such as cytotoxicity, photostability, and incompatibility. To this end, we synthesized special, hydrophobic, fluorescent, photostable, and non-cytotoxic carbon dots (CDs) by solvent-free thermal treatment using non-cytotoxic materials and incorporated into the lipid bilayers of giant unilamellar vesicles (GUVs) made from 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and dipalmitoylphosphatidylcholine (DPPC) lipids. A 2:2:1 mixture of DOPC, DPPC, and cholesterol (Chol) develops lipid rafts on the membrane by phase separation. The photophysical properties of the CDs get modulated on incorporation into the lipid rafts that identifies the membrane heterogeneity. The main attempt in this work is to develop a new, simple, cost-effective, and bio-friendly lipid raft marker, which can be used in biological applications, alongside other conventional raft markers, with more advantages.

Nickel-phenanthroline Complex Supported on Mesoporous Carbon as a Catalyst for Carboxylation under CO2 Atmosphere

Carbon dioxide is a highly potential renewable C1 source for synthesis of fine chemicals. Utilization of CO2 in carboxylation reactions requires catalysts, such as: nickel complex for CO2 activation. However, the use of homogeneous catalysts in the reaction is still less efficient due to the difficulty of separating the product and catalyst from reaction mixture. Therefore, it is necessary to heterogenize the nickel complex in a solid support such as mesoporous carbon. In this report, mesoporous carbon (MC) prepared from phloroglucinol and formaldehyde through soft template method was used as a solid support for Ni-phenanthroline complex (Ni-phen). The catalyst was characterized by Fourier Transform Infra Red (FT-IR), X-Ray Diffraction (XRD), Scanning Electron Microscope - Energy Dispersive X-Ray (SEM-EDX), and Surface Area Analyzer (SAA). The result of SAA characterization showed that the pore diameter of MC was 6.7 nm and Ni-phen/MC was 5.1 nm which indicates that the materials have meso-size pores. Ni-phen/MC material was then used as a heterogeneous catalyst in the carboxylation reaction of phenylacetylene under an ambient CO2 pressure. The reactions were carried out in several variations of conditions such as temperature, time and catalyst types. Based on the results of the reaction, the best conditions were obtained at 25 °C for 8 h of reaction time using Ni-phen/MC catalyst.  Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

A Nano-Rattle SnO2@carbon Composite Anode Material for High-Energy Li-ion Batteries by Melt Diffusion Impregnation

The huge volume expansion in Sn-based alloy anode materials (up to 360%) leads to a dramatic mechanical stress and breaking of particles, resulting in the loss of conductivity and thereby capacity fading. To overcome this issue, SnO₂@C nano-rattle composites based on <10 nm SnO₂ nanoparticles in and on porous amorphous carbon spheres were synthesized using a silica template and tin melting diffusion method. Such SnO₂@C nano-rattle composite electrodes provided two electrochemical processes: a partially reversible process of the SnO₂ reduction to metallic Sn at 0.8 V vs. Li⁺/Li and a reversible process of alloying/dealloying of Li_xSn_y at 0.5 V vs. Li⁺/Li. Good performance could be achieved by controlling the particle sizes of SnO₂ and carbon, the pore size of carbon, and the distribution of SnO₂ nanoparticles on the carbon shells. Finally, the areal capacity of SnO₂@C prepared by the melt diffusion process was increased due to the higher loading of SnO₂ nanoparticles into the hollow carbon spheres, as compared with Sn impregnation by a reducing agent.

Nanocatalysts for Electrocatalytic Oxidation of Ethanol

The use of ethanol as a fuel in direct alcohol fuel cells depends not only on its ease of production from renewable sources, but also on overcoming the challenges of storage and transportation. In an ethanol-based fuel cell, highly active electrocatalysts are required to break the C-C bond in ethanol for its complete oxidation at lower overpotentials, with the aim of increasing the cell performance, ethanol conversion rates, and fuel efficiency. In recent decades, the development of wet-chemistry methods has stimulated research into catalyst design, reactivity tailoring, and mechanistic investigations, and thus, created great opportunities to achieve efficient oxidation of ethanol. In this Minireview, the nanomaterials tested as electrocatalysts for the ethanol oxidation reaction in acid or alkaline environments are summarized. The focus is mainly on nanomaterials synthesized by using wet-chemistry methods, with particular attention on the relationship between the chemical and physical characteristics of the catalysts, for example, catalyst composition, morphology, structure, degree of alloying, presence of oxides or supports, and their activity for ethanol electro-oxidation. As potential alternatives to noble metals, non-noble-metal catalysts for ethanol oxidation are also briefly reviewed. Insights into further enhancing the catalytic performance through the design of efficient electrocatalysts are also provided.

The Enhanced Catalytic Performance and Stability of Ordered Mesoporous Carbon Supported Nano-Gold with High Structural Integrity for Glycerol Oxidation

Ordered mesoporous carbon (OMC) supported gold nanoparticles of size 3-4 nm having uniform dispersion were synthesized by sol-immobilization method. OMCs such as CMK-3 and NCCR-56 with high surface area and uniform pore size were obtained, respectively, using ordered mesoporous silicas such as SBA-15 and IITM-56 as hard templates, respectively. The resulting OMC supported monodispersed nano-gold, i. e., Au/CMK-3 and Au/NCCR-56, exhibited excellent performance as mild-oxidizing catalysts for oxidation of glycerol with high hydrothermal stability. Further, unlike activated carbon supported nano-gold catalysts (Au/AC), the OMC supported nano-gold catalysts, i. e., Au/CMK-3 and Au/NCCR-56, show no aggregation of active species even after recycling. Thus, in the case of Au/CMK-3 and Au/NCCR-56, both the fresh and regenerated catalysts showed excellent performane for the chosen reaction owing to an enhanced textural integrity of the catalysts and that with remarkable selectivity towards glyceric acid. The significance of the OMC supports in maintaining the dispersion of gold nanoparticles is explicit from this study, and that the activity of Au/AC catalyst is considerably decreased (∼50 %) upon recycling as a result of agglomeration of the active gold nanoparticles over the disordered amorphous carbon matrix.

Three-dimensional iron sulfide-carbon interlocked graphene composites for high-performance sodium-ion storage

Three-dimensional (3D) carbon-wrapped iron sulfide interlocked graphene (Fe7S8@C-G) composites for high-performance sodium-ion storage are designed and produced through electrostatic interactions and subsequent sulfurization. The iron-based metal-organic frameworks (MOFs, MIL-88-Fe) interact with graphene oxide sheets to form 3D networks, and carbon-wrapped iron sulfide (Fe7S8@C) nanoparticles with high individual-particle conductivity are prepared following a sulfurization process, surrounded by interlocked graphene sheets to enhance the interparticle conductivity. The prepared Fe7S8@C-G composites exhibit not only improved individual-particle and interparticle conductivity to shorten electron/ion diffusion pathways, but also enhanced structural stability to prevent the aggregation of active materials and buffer large volume changes during sodiation/desodiation. As a sodium-ion storage material, the Fe7S8@C-G composites exhibit a reversible capacity of 449 mA h g-1 at 500 mA g-1 after 150 cycles and a retention capacity of 306 mA h g-1 under a current density of 2000 mA g-1. The crucial factors related to the structural changes and stability during cycles have been further investigated. These results demonstrate that the high-performance sodium-ion storage properties are mainly attributed to the uniquely designed three-dimensional configuration.

Metal-Nitrogen-doped Porous Carbons Derived from Metal-Containing Ionic Liquids for Oxygen Reduction Reaction

This study describes a self-doping and additive-free strategy for the synthesis of metal-nitrogen-doped porous carbon materials (CMs) via carbonizing well-tailored precursors, metal-containing ionic liquids (M-ILs). The organic skeleton in M-ILs serves as both carbon and nitrogen sources, while metal ions acts as porogen and metallic dopants. A high nitrogen content, appropriate content of metallic species and hierarchical porosity synergistically endow the resultant CMs (MIBA-M-T) as effective electrocatalysts for the oxygen reduction reaction (ORR). MIBA-Fe-900 with a high specific surface area of 1567 m²  g^-1 exhibits an activity similar to that of Pt/C catalyst, a higher tolerance to methanol than Pt/C, and long-term durability. This work supplies a simple and convenient route for the preparation of metal-containing carbon electrocatalysts.

One pot synthesis of CeO2 nanoparticles on a carbon surface for the practical determination of paracetamol content in real samples

Sucrose derived carbon decorated with CeO₂ nanoparticles (CeO₂–C) was prepared using a one pot synthesis and used for the electrochemical sensing of paracetamol.

Mesoporous hollow carbons on graphene and their electrochemical properties

We synthesized mesoporous hollow carbon on a graphene surface (MHCG). When applied into supercapacitor electrode, MHCG electrode exhibited outstanding maintenance of energy density above 30 W h kg⁻¹ even under 1 kW kg⁻¹ power density.

Multiwalled carbon nanotubes coated with a thin carbon layer for use as composite electrodes in supercapacitors

A sucrose-derived thin carbon layer (CS) is coated onto the surface of multiwalled carbon nanotubes (MWCNTs). The resulting composite electrode (CSN) has a larger capacitance than that of the MWCNTs and the CS.