Fullerene hollow microspheres prepared by bubble-templates as sensitive and selective electrocatalytic sensor for biomolecules

Supramolecular Engineering of Crystalline Fullerene Micro-/Nano-Architectures

Fullerenes are a molecular form of carbon allotrope and bear certain solubility, which allow the supramolecular assembly of fullerene molecules-also together with other complementary compound classes-via solution-based wet processes. By well-programmed organizing these building blocks and precisely modulating over the assembly process, supramolecularly assembled fullerene micro-/nano-architectures (FMNAs) are obtained. These FMNAs exhibit remarkably enhanced functions as well as tunable morphologies and dimensions at different size scales, leading to their applications in diverse fields. In this review, both traditional and newly developed assembly strategies are reviewed, with an emphasis on the morphological evolution mechanism of FMNAs. The discussion is then focused on how to precisely regulate the dimensions and morphologies to generate functional FMNAs through solvent engineering, co-crystallization, surfactant incorporation, or post-fabrication treatment. In addition to C₆₀ -based FMNAs, this review particularly focuses on recently fabricated FMNAs comprising higher fullerenes (e.g., C₇₀ ) and metallofullerenes. Meanwhile, an overview of the property modulation is presented and multidisciplinary applications of FMNAs in various fields are summarized, including sensors, optoelectronics, biomedicines, and energy. At the end, the prospects for future research, application opportunities, and challenges associated with FMNAs are proposed.

Hollow Spherical Fullerene obtained by Kinetically Controlled Liquid-Liquid Interfacial Precipitation

Nanomaterials with hollow structures are expected to exhibit new functionalities for materials engineering. Here we report the fabrication of fullerene (C 60 ) spheres having different hollow structures by using a kinetically controlled liquid-liquid interfacial precipitation (KC-LLIP) method. For this purpose, 1,2-ethylenediamine (EDA) was used as a covalent cross-linker of C 60 molecules to form C 60 -EDA shells, while in-situ generated EDA-sulfur (EDA-S) droplets were applied as 'yolks' being eliminated by washing following formation of the yolk-shell structure, leading to hollow structures. Porous spheres, string hollow spheres, hollow spheres, and open hollow spheres have been synthesized by controlling the kinetics of nucleation of C 60 -EDA and the template EDA-S growth. Isopropanol was used as an additive to control the discrepancy in growth rates of C 60 -EDA and EDA-S. This facile KC-LLIP preparation method is expected to facilitate the large-scale fabrication and application of structured C 60 spheres in materials science and technology.

Fullerene superlattices containing charge transfer complexes for an improved nonlinear optical performance

To improve the nonlinear optical (NLO) properties of fullerene C₆₀, chemical modifications are normally needed to construct a donor-π-acceptor (D-π-A) system, which requires tedious and time-consuming synthesis procedures. In addition, the conjugated structure of C₆₀ will inevitably be destroyed, which is disadvantageous for other applications. Here, we use solvent-based nanoarchitectonics to obtain highly ordered, three-dimensional (3D) C₆₀ supramolecular structures. For this purpose, a liquid-liquid interfacial precipitation (LLIP) method was employed using quinoline as the good solvent. Hollow polyhedra (HPH) and multilayer flowers (MFs) were obtained when methanol and ethanol were selected as the poor solvents, respectively. While quinoline failed to enter the HPH, it was found to be successfully intercalated with the MFs, which induced a transition of the C₆₀ organization from a pristine face-centered-cubic (fcc) phase to a hexagonal close packed (hcp) lattice. When embedded in a poly(methyl methacrylate) (PMMA) matrix, the HPH and MFs both show reverse saturable absorption (RSA) and optical limiting (OL) properties. The MFs-based film showed a third-order nonlinear absorption coefficient (β) of 1.25 × 10⁵ cm·GW^-1 and an optical limiting threshold (F_ol) of 0.00625 J·cm^-2. Comparatively, the HPH-based film exhibited a lower β value of 9.80 × 10⁴ cm GW^-1 and a higher F_ol value of 0.00834 J cm^-2. The better NLO performance of the MFs was mainly ascribed to the formation of the charge transfer complexes between quinoline and C₆₀, proven by UV-vis and electrochemical measurements. The fine tuning of the NLO properties of C₆₀ without chemical modification provides new opportunities for C₆₀ to be applied in nonlinear optics.

On demand synthesis of hollow fullerene nanostructures

Hollow nanostructures are widely used in chemistry, materials, bioscience, and medicine, but their fabrication remains a great challenge. In particular, there is no effective strategy for their assembly and interconnection. We bring pottery, the oldest and simplest method of fabricating hollow containers, into the nanoscale. By exploiting the liquid nature of the xylene template, fullerene hollow nanostructures of tailored shapes, such as bowls, bottles, and cucurbits, are readily synthesized. The liquid templates permit stepwise and versatile manipulation and hence, modular assembly of nodes and junctions leads to interconnected hollow systems. As a proof-of-concept, we create multi-compartment nano-containers, with different nanoparticles isolated in the separate pockets. This methodology expands the synthetic freedom for hollow nanostructures, building a bridge from isolated hollow units to interconnected hollow systems.

At nanoscale, it is synthetically very difficult to increase the structural complexity of hollow structures. Here, the authors use a stepwise liquid templating strategy to build, assemble, and interconnect fullerene hollow nanostructures, just like the synthetic freedom one could have with pottery.

Enantioselective analysis of D- and l- Serine on a layer-by-layer imprinted electrochemical sensor

The present work describes a new, simple, and easy method of generating acrylamide functionalised reduced graphene oxide-fullerene layer-by-layer assembled dual imprinted polymers to quantify D- and L-Serine at ultra trace level in aqueous and real samples. Herein, the pencil graphite electrode was initially spin coated with D-Serine imprinted acrylamide functionalized reduced graphene oxide. After 10 min thermal treatment (50 °C), this electrode was again modified with L-Serine imprinted acrylamide functionalized fullerene molecules. This bilayer assembly was finally made thermally stable by 60 °C exposure for 3 h. The proposed sensor showed better electronic properties with an improved synergism. We have compared this modified electrode with other modified pencil graphite electrodes like single layered acrylamide functionalised reduced graphene oxide or fullerene, single layered acrylamide functionalised reduced graphene oxide-fullerene composite and double layered acrylamide functionalised reduced graphene oxide or fullerene molecules, which yielded very inferior sensitivity due to possible agglomeration and decreased synergism. The chosen system demonstrated a very good analytical figures of merit with differential pulse anodic stripping voltammetry and cyclic voltammetry transduction, showing lower limits of detection (0.24 ng mL^-1, S/N = 3) for both isomers. The proposed sensor assures practical applications as disease biomarker, manifesting several diseases at very ultra-trace level.

New Approach for Porous Chitosan-Graphene Matrix Preparation through Enhanced Amidation for Synergic Detection of Dopamine and Uric Acid

Amide-functionalized materials have emerged as promising nonprecious catalysts for electrochemical sensing and catalysis. The covalent immobilization of chitosan (CS) onto graphene sheet (GS) (denoted as CS-GS) has been done via higher degree of amidation reaction to develop an electrochemical sensing matrix for simultaneous determination of dopamine (DA) and uric acid (UA). The enhanced amidation between CS and GS has not been reported previously. However, electrochemical results have revealed that the CS-GS enhances the electrocatalytic performance in terms of the oxidation potential and peak current due to the higher degree of amide functionalization compared to that of CS/GS, which has a lower amidation. Differential pulse voltammetry-based studies have indicated that the CS-GS matrix works at a lower detection limit (0.14 and 0.17 μM) (S/N = 3) and over a longer linear range (1-700 and 1-800 μM), with a comparatively higher sensitivity (2.5 and 2.0 μA μM^-1 cm^-2), for DA and UA, respectively. In addition, the CS-GS matrix demonstrates good selectivity toward the detection of DA and UA in the presence of a 10-fold higher concentration of AA and glucose. The as-prepared three-dimensional porous CS-GS also endows selective determination toward DA and UA in various real samples.

Selective growth of fullerene octahedra and flower-like particles by a liquid–liquid interfacial precipitation method for super-hydrophobic applications

Super-hydrophobic fullerene octahedron and flower-like microcrystals with a high water contact angle of 158.8° were prepared using anisole and IPA in a liquid–liquid interfacial precipitation method.

Facile Method toward Hierarchical Fullerene Architectures with Enhanced Hydrophobicity and Photoluminescence

A two-step self-assembly strategy has been developed for the preparation of fullerene hierarchical architectures. Typically, the precipitation method is utilized to synthesize the initial fullerene microstructures, and subsequently a drop-drying process is employed to facilitate the fullerene microstructures to self-assemble into the final hierarchical structures. Overall, this methodology is quite simple and feasible, which can be applied to prepare fullerene hierarchical structures with different morphological features, simply by choosing proper solvent. Moreover, the as-obtained C70 hierarchical structures have many superior properties over the original C70 microrods such as superhydrophobicity and unique photoluminescence behaviors, promising their applications as waterproof optoelectronics.

Vortex-aligned fullerene nanowhiskers as a scaffold for orienting cell growth

A versatile method for the rapid fabrication of aligned fullerene C60 nanowhiskers (C60NWs) at the air-water interface is presented. This method is based on the vortex motion of a subphase (water), which directs floating C60NWs to align on the water surface according to the direction of rotational flow. Aligned C60NWs could be transferred onto many different flat substrates, and, in this case, aligned C60NWs on glass substrates were employed as a scaffold for cell culture. Bone forming human osteoblast MG63 cells adhered well to the C60NWs, and their growth was found to be oriented with the axis of the aligned C60NWs. Cells grown on aligned C60NWs were more highly oriented with the axis of alignment than when grown on randomly oriented nanowhiskers. A study of cell proliferation on the C60NWs revealed their low toxicity, indicating their potential for use in biomedical applications.

One-step pyrolytic synthesis of nitrogen and sulfur dual-doped porous carbon with high catalytic activity and good accessibility to small biomolecules

As one of promising catalysts that contain high density of active sites, N doped carbons have been extensively researched, while the reports for N, S dual-doped carbon materials are far less exhaustive. Herein, devoid of activation process and template, N, S dual-doped porous carbon (N-S-PC) was prepared for the first time via one-step pyrolysis of sodium citrate and cysteine. Possessing unique porous structure and large pore volume as well as good accessibility, N-S-PC demonstrates significantly improved electrocatalytic activity toward oxidation of ascorbic acid (AA), dopamine (DA), and uric acid (UA). In the coexisting system, the peak potential separation between AA and DA is up to 251 mV, which is much larger than for most of the other carbons. On the basis of large potential separation and high current response, selective and sensitive simultaneous determination of AA, DA, and UA was successfully accomplished by differential pulse voltammetry, displaying a linear response from 50 to 2000 μM, from 0.1 to 50 μM, and from 0.1 to 50 μM with a detection limit (S/N = 3) of 0.78, 0.02, and 0.06 μM. This work highlights the importance of N, S dual doping and hierarchical porous carbons for efficient catalysis.

Interfacial Janus gold nanoclusters as excellent phase- and orientation-specific dopamine sensors

This investigation, following our recent report on the one-pot hemi-micellar interfacial synthesis of Janus gold nanoclusters and the inter-cluster electron coupling establishing insulator-metal transition in the oriented Janus monolayers [Langmuir, 2010, 26(17), 14047], was to fabricate modified electrodes for sensing dopamine, the neurotransmitter. With a detection limit in the sub-nanomolar range, the apparent electron transfer rate constants for dopamine detection signified an intricate Janus cluster 2D phase dependency. Surface pressure as a thermodynamic variable controlled the electronic communication between the clusters as a result of varied inter-cluster distance and size, ultimately reflecting on the sensitivity and detection limit for dopamine sensing. The non-covalent nature of the ligands on the core metal clusters facilitated the overall electro-catalytic oxidation of dopamine. The notable feature of this precise work was that it established a more effective phase- and orientation-specific Janus cluster sensing than those reported through patterned gold nanowire based sensors.