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Embedding endohdedral metallofullerenes (EMFs) into electron donor-acceptor systems is still a challenging task owing to their limited quantities and their still largely unexplored chemical properties. In this study, we have performed a 1,3-dipolar cycloaddition reaction of a corrole-based precursor with Sc3 N@C80 to regioselectively form a [5,6]-adduct (1). The successful attachment of the corrole moiety was confirmed by mass spectrometry. In the electronic ground state, absorption spectra suggest sizeable electronic communications between the electron acceptor and the electron donor. Moreover, the addition pattern occurring at a [5,6]-bond junction is firmly proven by NMR spectroscopy and electrochemical investigations performed with 1. In the electronically excited state, which is probed in photophysical assays with 1, a fast electron-transfer yields the radical ion pair state consisting of the one-electron-reduced Sc3 N@C80 and of the one-electron-oxidized corrole upon its exclusive photoexcitation. As such, our results shed new light on the practical work utilizing EMFs as building blocks in photovoltaics.

Non-enzymatic glucose biofuel cells (GBFCs) has been renewed interest because of good long-term stability and adequate power density. Here we demonstrate the application of a three-dimensional (3D) nanocomposites electrode for implantable GBFCs with simple fabrication protocol, good performance (a high power density 2.3 mW cm −2 and an open circuit potential 0.70 V in physiological environment) and excellent stability. 3D flowerlike platinum (Pt) nanoparticle clusters are electrodeposited onto multiwalled carbon nanotubes (MWCNTs) by using an all-electrochemical protocol, which involves a key, second step of a potential pulse sequence. The potential widths can change the size and distance of the nuclei and clusters. The resulting 3D Pt morphology of a new type is found to exhibit significantly higher electrocatalytic activity and better stability than the dispersive morphology for glucose oxidation reaction (GOR) and oxygen reduction reaction (ORR). We also investigate the application (polarization test, biofuel cell performance and degradation behavior) of this process for the fabrication of both anode and cathode in GBFCs. This new procedure might give credence for construction of a new generation of GBFCs operating at mild conditions or boost the power outputs and make them suitable for diverse applications.

Sulfur-doped graphene quantum dots (S-GQDs) with stable blue-green fluorescence were synthesized by one-step electrolysis of graphite in sodium p-toluenesulfonate aqueous solution. Compared with GQDs, the S-GQDs drastically improved the electronic properties and surface chemical reactivities, which exhibited a sensitive response to Fe(3+). Therefore, the S-GQDs were used as an efficient fluorescent probe for highly selective detection of Fe(3+). Upon increasing of Fe(3+) concentration ranging from 0.01 to 0.70 μM, the fluorescence intensity of S-GQDs gradually decreased and reached a plateau at 0.90 μM. The difference in the fluorescence intensity of S-GQDs before and after adding Fe(3+) was proportional to the concentration of Fe(3+), and the calibration curve displayed linear regions over the range of 0-0.70 μM. The detection limit was 4.2 nM. Finally, this novel fluorescent probe was successfully applied to the direct analysis of Fe(3+) in human serum, which presents potential applications in clinical diagnosis and may open a new way to the design of effective fluorescence probes for other biologically related targets.

We demonstrate that boron-doping of graphene quantum dots (B-GQDs) give rise to rich fluorescence owing to their peculiar interaction with the surrounding media. A B-GQDs borax (Na2B4O7·10H2O) solution was shown to be highly fluorescent in green, and upon evaporation, formed bright green fluorescent crystals. However, removing the borax left behind only blue and yellow luminescent solutions. These intriguing findings are rationalized by the insight that B-GQDs associate in the absence of borax whereas they form dative valence bonds with the bridgehead O atoms of borax in the presence of borax. We further demonstrate the use of the B-GQDs, for example, in chemosensor for detecting Al3+ and biomarker for cellular imaging.

A full-electrochemical method is developed to deposit three dimension structure (3D) flowerlike platinum-ruthenium (PtRu) and platinum-ruthenium-nickel (PtRuNi) alloy nanoparticle clusters on multi-walled carbon nanotubes (MWCNTs) through a three-step process. The structure and elemental composition of the PtRu/MWCNTs and PtRuNi/MWCNTs catalysts are characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray polycrystalline diffraction (XRD), IRIS advantage inductively coupled plasma atomic emission spectroscopy (ICP-AES), and X-ray photoelectron spectroscopy (XPS). The presence of Pt(0), Ru(0), Ni(0), Ni(OH)2, NiOOH, RuO2 and NiO is deduced from XPS data. Electrocatalytic properties of the resulting PtRu/MWCNTs and PtRuNi/MWCNTs nanocomposites for oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) are investigated. Compared with the Pt/MWCNTs, PtNi/MWCNTs and PtRu/MWCNTs electrodes, an enhanced electrocatalytic activity and an appreciably improved resistance to CO poisoning are observed for the PtRuNi/MWCNTs electrode, which are attributed to the synergetic effect of bifunctional catalysis, three dimension structure, and oxygen functional groups which generated after electrochemical activation treatment on MWCNTs surface. The effect of electrodeposition conditions for the metal complexes on the composition and performance of the alloy nanoparticle clusters is also investigated. The optimized ratios for PtRu and PtRuNi alloy nanoparticle clusters are 8:2 and 8:1:1, respectively, in this experiment condition. The PtRuNi catalyst thus prepared exhibits excellent performance in the direct methanol fuel cells (DMFCs). The enhanced activity of the catalyst is surely throwing some light on the research and development of effective DMFCs catalysts.

The surface charge-tunable Fe3O4 nanoparticles with high dispersibility and high superparamagnetism are fabricated by a facile electrochemical method in acetonitrile solution. These nanoparticles can reversibly bind to graphene oxides, which could be recycled and continually used for high-efficient removal of dye pollutants from water.

Carbon quantum dots (CQDs) have emerged as promising materials for optoelectronic applications on account of carbon’s intrinsic merits of high stability, low cost and environment-friendliness. However, the CQDs usually give broad emission with full width at half maximum exceeding 80 nm, which fundamentally limit its display applications. We demonstrate multicolored narrow bandwidth emission (full width at half maximum of 29 to 30 nm) from triangular CQDs with a quantum yield up to 54 to 72%. Detailed structural and optical characterizations together with theoretical calculations revealed that the molecular purity and crystalline perfection of the triangular CQDs are key to the high color-purity. Moreover, multicolored light-emitting diodes based on these CQDs displayed good stability, high color-purity and high-performance with maximum luminance of 1882 to 4762 cd m-2 and current efficiency of 1.22 to 5.11 cd A-1. This work will set the stage for developing next-generation high-performance CQDs-based light-emitting diodes.

We report water-soluble, 3 nm uniform-sized graphene quantum dots (GQDs) with red emission prepared by electrochemical exfoliation of graphite in K2S2O8 solution. Such GQDs show a great potential as biological labels for cellular imaging.

Pt nanoflowers (NFs) with uniform size and high dispersion have been inserted between sheets of graphene through a three-step protocol consisting of ZnO nanoparticle (NP) expansion of graphite, electrochemical deposition of PtCl62−, and dissolution of the ZnO NPs. The key synthesis strategy employs ZnO NPs as the insertion to increase the graphite interlayer distance for insertion of PtCl62− but avoid the preparation of graphene oxides (GOs) and further reduction processes. The resulting Pt NF/graphene-layered composites are characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and Raman spectra. The results show that highly dispersed Pt NFs with a uniform size of 250 nm insert between the graphene sheets and exhibit significantly higher electrocatalytic activity and better stability for the oxidation of methanol compared to Pt NFs deposited on the surface of graphite and GOs. These attractive features are a result of the layered structure consisting of alternating highly dispersed Pt NFs with high surface area and graphene with high conductivity. Our work provides a new route for the preparation of Pt NF/graphene-layered composites, which are promising electrocatalysts for direct methanol fuel cells.

As advanced electrodes for direct alcohol fuel cells, graphene-Pd and graphene-Pt composites with a trace of SnO(2) have been successfully synthesized by a modified electroless plating technique. The surface of graphene oxide is first sensitized by Sn(2+) ions, and subsequently, Pd or Pt nanoparticles are deposited on the surface of graphene oxide. Finally, graphene oxide was reduced to graphene by further adding NaBH(4). Compared to other carbon-(e.g., Vulcan XC-72R) supported Pd and Pt, the resultant graphene-Pd and Pt composites exhibit better electrocatalytic activity and long-term stability toward alcohol electrooxidation. Additionally, a trace amount of SnO(2) formed around active catalysts may also be beneficial to the enhancement of electrochemical activity.

A novel template-assisted deposition and etching strategy is proposed in this paper for preparing IrO 2 nanotube arrays on ITO substrates, i.e., electrodepositing IrO 2 nanoparticles onto ZnO nanorod surfaces to produce IrO 2 -coated core–shell nanorod arrays, and followed by wet chemical etching the ZnO nanorods away to generate IrO 2 nanotube arrays. Well-aligned IrO 2 nanotube arrays with high purity and uniform size are produced by using this synthetic strategy. Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) are employed to examine the morphology, fine structure and composition of the IrO 2 nanotube arrays intensively. Furthermore, electrocatalytic water oxidization experiments are performed to assess the catalytic performance of the as-prepared IrO 2 nanotube arrays toward oxygen evolution reaction (OER). The IrO 2 nanotube arrays have been found to possess an excellent catalytic performance: high turnover frequency (3.3 s − 1 for TOF at 1.2 V versus Ag/AgCl), low oxygen evolution overpotential ( η = 0.15 V) and good catalytic stability (55% catalytic activity remaining after undergoing 400 times potential cycles).

Potassium ions play diverse roles in biological processes, and abnormal K(+) levels are the hallmarks of diseases. However, the potential clinical application of the developed DNA-based K(+) sensors remains a challenge due to the presence of Pb(2+) in blood samples. In this contribution, a novel colorimetric potassium sensing assay that functions in the presence of Pb(2+) is reported. This approach is based on conformational switching of a hairpin DNA structure to a G-quadruplex. Specifically, the hairpin DNA containing G-rich aptamer T30695 is exposed to successive amounts of Na(+), Pb(2+) and K(+). These cations induce formation of the corresponding metal-stabilized G-quadruplex, which acts as DNAzyme (with hemin as a cofactor) for the catalytic oxidation of ABTS by H(2)O(2). Importantly, studies presented here show that K(+) replaces Pb(2+) from the G-quadruplex to form K(+)-stabilized G-quadruplex, which differ in the catalytic behavior. With Pb(2+)-stabilized G-quadruplex as a probe, a highly sensitive and selective colorimetric detection of K(+) is achieved in the presence of Pb(2+) and excessive Na(+) (140 mM) with the detection limit of 1.9 nM. This system represents the first known DNAzyme-based colorimetric K(+) sensor, which works in the presence of Pb(2+). Finally, the sensor is successfully applied for K(+) detection in a real human serum sample containing Pb(2+).

Here, we first find that Na

Multicolor bandgap fluorescent carbon quantum dots (MCBF-CQDs) from blue to red with quantum yield up to 75% are synthesized using a solvothermal method. For the first time, monochrome electroluminescent light-emitting diodes (LEDs) with MCBF-CQDs directly as an active emission layer are fabricated. The maximum luminance of blue LEDs reaches 136 cd m-2 , which is the best performance for CQD-based monochrome electroluminescent LEDs.

We report on the synthesis of a composite made from iridium oxide and gold that has a flower-like morphology. The ratio of iridium oxide to gold can be controlled by altering the concentrations of the metal precursors or the pH of the solution containing the reductant citrate. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and laser confocal micro-Raman spectroscopy were applied to characterize the structures of the nanoflowers, and a mechanism of their formation was deduced. The nanoflowers display an electrocatalytic activity in an oxygen evolution reaction (OER) that is significantly enhanced compared to bare iridium oxide nanoparticles. The highest turnover frequency for the OER of the new nanoflowers is 10.9 s−1, which is almost one order of magnitude better than that of the respective nanoparticles. These attractive features are attributed to the high oxidation states of iridium in the nanoflowers which is caused by the transfer of electronic charge from metal oxides to gold, and also to the flower fractal structure which is thought to provide a much more accessible surface than suspensions of the respective nanoparticle.

A novel catalyst-free synthetic strategy for producing high-quality CdTe nanowires in solution is proposed. A special reaction condition is intentionally constructed in the reaction system to induce the formation of nanowires through oriented in situ assembly of tiny particles. To establish such special synthetic conditions in the CdTe system, not only are its typical features and possible solutions deeply analyzed, but also related factors, such as the ligand environment, injection and growth temperature, and Cd-to-Te precursor ratio, are systemically investigated. High-quality ultralong (up to 10 μm) and ultrathin (less than 10 nm) CdTe nanowires are produced in solution under optimal reaction conditions. Morphological, spectral, and compositional analyses are performed to examine the products formed at different reaction stages in order to clarify the formation mechanism of the CdTe nanowires. Furthermore, the transformation of the CdTe nanowires into CdTe/CdSe core–shell heterostructures is intensively explored, and the CdSe epitaxial growth process is specially tracked by morphological and spectral characterization techniques. Finally, CdTe nanowires coated with a continuous and dense CdSe shell are successfully fabricated by using a proper coating protocol.

Pd/Au hollow cone-like microstructures (HCMs) have been electrodeposited on indium tin oxide (ITO) using a two-step protocol, which involves the nucleation pulse and succedent constant potential reduction in the presence of metal precursors and polyvinylpyrrolidone (PVP). Scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscope (XPS) were used to characterize the Pd/Au HCMs. The electrochemical results (cyclic voltammetry and chronoamperometry) testify that the Pd/Au HCMs exhibit significantly higher electrocatalytic activity and stability for the oxidation of formic acid than that of Pd/Au solid microhemispheres (SMHs). These attractive features are attributable to the unique hollow structures of Pd/Au with much higher electrochemical active surface areas and the exposure of favorable planes. Our work points to a new path for the preparation of Pd/Au HCMs, which are promising as electrocatalysts in direct formic acid fuel cell (DFAFC).

Aqueous solutions of fluorescent ultrafine C60 nanoparticles have been successfully prepared by an electrochemical method, which involves reducing a C60 film to C603− anions in the presence of tetrabutylammonium (TBA+) cations in acetonitrile solution and transferring to water. The nanoparticles are highly emissive in the visible region. The structure of the fluorescent C60 nanoparticles was deduced as a ∼5 nm sphere with a solid core of aggregated C60 and an anionic shell of C603−, which renders the nanoparticles water soluble. The photostable and nontoxic C60 nanoparticles can easily penetrate into live cells, and are thus primed for a host of biomedical applications.

Bowl-like nanostructures of Pt/Pd bimetallic nanocrystals are prepared by employing Ag nanoparticles as a template and completely removing the residual Ag after the displacement. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations display that the thin walls of Pt/Pd nanobowls are composed of nanoparticles. X-ray diffraction (XRD) pattern demonstrates that Pt and Pd form the alloy in the nanobowls. The crystal structures of the nanobowls consist of [1 1 1], [2 0 0], [2 2 0] surfaces as revealed by both high-resolution TEM (HRTEM) and XRD results. The Pt/Pd nanobowls exhibit significant high electrocatalytic activities toward the methanol oxidation and oxygen reduction compared with the Pt/Pd nanospheres and Pt nanobowls.

A novel ligand tuning strategy for the synthesis and assembly of ZnTe nanocrystals is proposed in this paper: a specific ligand is selected to work with the reaction system to regulate (passivate or activate) the reactivity of zinc precursors, as well as the growth and the assembly of resulting nanocrystals in a coordinate way. By utilization of this strategy, high-quality ZnTe nanodots, branched-nanorods (including nanotetrapods), nanowires and microspheres are obtained. Furthermore, by using ZnTe microspheres as building blocks, ordered two-dimensional (2D) and three-dimensional (3D) arrays and well-defined hollow microspheres are fabricated. The size, morphology, and crystal structure of as-prepared ZnTe nanocrystals are well characterized. The underlying mechanisms for ligand-tuned synthesis and assembly of ZnTe nanocrystals are also intensively discussed. Finally, the shape-dependent optical, structural, and electrochemical properties of those ZnTe nanocrystals are systemically investigated; their ba...

Clinical translation of therapeutic peptides, particularly those that require penetration of the cell membrane or are cytolytic, is a major challenge. A novel approach based on a complementary mechanism, which has been widely used for guided synthesis of DNA or RNA nanoparticles, for de novo design of activatable protein nanoparticles (APNPs) for targeted delivery of therapeutic peptides is described. APNPs are formed through self-assembly of three independent polypeptides based on pairwise coiled-coil dimerization. They are capable of long circulation in the blood and can be engineered to target diseases. Peptides to be delivered are incorporated into APNPs and released into the disease microenvironment by locally enriched proteases. It is demonstrated that APNPs mediate efficient delivery of NR2B9c, a neuroprotective peptide that functions after cell penetration, and melittin, a cytolytic peptide that perturbs the lipid bilayer, for effective treatment of stroke and cancer, respectively. Due to their robust properties, simple design, and economic costs, APNPs have great potential to serve as a versatile platform for controlled delivery of therapeutic peptides.

Crystal orientation-ordered C60 nanorod bundles have been assembled, where each C60 nanorod maintains its individual shape and identity with unpolymerized bucky balls and all of the nanorods are vertically aligned with a high density. The key to this lies in the assembly of the C60 nanorod bundles from the nanoscopic to microscopic and macroscopic scale. The novel structure of C60 nanorod bundles leads to a high photoresponse, which is promising for applications in optical devices.

Electrochemical detection of dopamine (DA) in the presence of a large excess of ascorbic acid (AA) was investigated with a novel all-carbon nanocomposite film of C60-MWCNTs (C60-functionalized multi-walled carbon nanotubes) using a bare MWCNTs film as control. Although both films can selectively detect DA from AA by separating their oxidation potentials, the C60-MWCNTs film shows special selectivity and good sensitivity for detecting DA. On one hand, the C60-MWCNTs composite film shows a higher activity for DA oxidation with enhanced peak current. On the other hand, the C60-MWCNTs composite film effectively suppresses the oxidation of AA. Remarkably, it is found that the oxidation current of DA is over 2 times higher than that of AA even when the concentration of AA is about 3 to 4 orders of magnitude higher than that of DA. This offers a tremendous advantage for the simple and clean detection of DA free of the interfering AA signal in a real assay. Cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectrometry are used to characterize the C60-MWCNTs composite film. These novel properties are interpreted to arise from the facile electron transfer between C60 and MWCNTs in the C60-MWCNTs nanocomposite film.

The electrochemical behavior of trimetallic nitride clusterfullerene (Sc3N@C78) embedded in films of the cationic surfactant didodecyldimethylammonium bromide (DDAB) on glassy carbon (GC) electrodes in aqueous solution was investigated. Four pairs of reversible redox peaks were observed in the potential range between +0.6 and −0.9 V vs. SCE. Different to the electrochemistry of pristine Sc3N@C78 in organic solution, the first reduction is a one-electron rather than simultaneous two-electron process because of the strong binding between DDA+ and the monoanion of Sc3N@C78. The generated radial monoanion, dianion and trianion of Sc3N@C78 are stable during continuous potential cycling, while some chemical reactions take place when the third anion is further reduced in the films. The cyclic voltammograms of Sc3N@C78/DDAB films checked at different temperatures pointed to strong temperature dependence. The electrochemical processes were also measured in different electrolytes, which showed pronounced anionic dependence and no cathodic dependence on either the cation or anions present. A possible electron-transfer mechanism of a Sc3N@C78/DDAB film was presented.

A grapevine nanostructure based on single-walled carbon nanotubes (SWNTs) covalently functionalized with [60]fullerene (C60) has been synthesized and characterized in detail. Investigations into the ball-on-tube carbon nanostructure by ESR spectroscopy indicate a tendency for ground-state electron transfer from the SWNT to the C60 moieties. The cyclic-voltammetric response of the nanostructure film exhibits reversible multiple-step electrochemical reactions of the dispersed C60, which are strikingly similar to those of the C60 derivatives in solution, but with consistent negative shifts in the redox potential. This results from the covalent linkage of C60 to the surfaces of the SWNTs in the form of monomers and manifests the electronic interaction between the C60 and SWNT moieties.

Electrochemical behavior of Sc3N@C78 solution was investigated for the first time by cyclic voltammetry (CV) as well as differential pulse voltammetry (DPV). Reversible redox features of Sc3N@C78 were obtained in contrast to that of Dy3N@C78, for which the corresponding redox waves were very recently found to be irreversible. Toluene/MeCN and four other solvents have been identified, wherewith reversible redox waves can also be observed for Sc3N@C80 (Ih) at a normal potential scan rate, whereas o-dichlorobenzene (o-DCB) was found to give only irreversible redox behavior as concluded by other researchers. The redox properties of Sc3N@C78 and Sc3N@C80 (Ih) are comparatively discussed on the basis of their different electronic structures and interactions with the solvent molecules. Additionally, electrochemical energy gaps of both Sc3N@C78 and Sc3N@C80 (Ih) were obtained.

An electrochemical method was developed to deposit platinum (Pt) and nickel (Ni) nanoparticles on multi-walled carbon nanotubes (MWCNTs) through a three-step process. X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) show the alloy formation for Pt and Ni with a ratio of 1:1. The presence of Pt(0), Ni(0), Ni(OH)2, NiOOH and slight NiO was deduced from XPS data. Electrocatalytic properties of the resulting PtNi/MWCNT electrode for methanol oxidation reaction were investigated. Compared with Pt/MWCNT, an appreciably improved resistance to CO poisoning was observed for the PtNi/MWCNT electrode, which was interpreted by a mechanism based on the bifunctional catalysis. The successful preparation of PtNi/MWCNT nanocomposites opens a new path for an efficient dispersion of the promising electrocatalysts in the direct methanol fuel cells.

3D flowerlike Pt nanoparticle clusters are electrodeposited onto multiwalled carbon nanotubes (MWCNTs) by using a three-step protocol, which is all-electrochemical and involves a key, second step of a potential pulse sequence. This 3D fractal morphology is in marked contrast to the 2D uniform nanoparticle dispersion of MWCNTs, which is achieved when the second step adopts cyclic voltammetry instead of a potential-step method. The former is found to exhibit significantly higher electrocatalytic activity and better stability than the latter for oxidation of methanol. These attractive features are attributable to the unique 3D flowerlike structure of Pt nanoparticle clusters on MWCNTs with much higher electrochemically active surface areas. Our work points to a new path for the preparation of 3D Pt/MWCNT nanocomposites, which are promising as electrocatalysts in direct methanol fuel cells.

A turn-on orange-red fluorescent nanosensor based on rhodamine B derivative-functionalized graphene quantum dots (RBD-GQDs) has been successfully synthesized for Fe3+ detection with high sensitivity and selectivity. By connecting with GQDs, the water solubility, sensitivity, photostability, and biocompatibility of RBD are drastically improved. The most distinctive feature of the RBD-GQDs, which sets them apart from other previously reported fluorophores or GQDs, is that they with the detection limits as low as 0.02 μM are demonstrated as a Fe3+ turn-on fluorescent nanosensor in cancer stem cells. Fe3+ binding to such GQDs (RBD-GQDs-Fe3+) with orange-red fluorescence of 43% quantum yield were demonstrated to be the biomarkers for cancer stem cell imaging. Refereed/Peer-reviewed

Direct and rapid detection of 1-hydroxypyrene (1-OHP) is of great importance owing to its high carcinogenicity, teratogenicity and toxicity. In this study, a simple colorimetric assay for rapid determination of 1-OHP is reported, which is based on non-crosslinking aggregation of gold nanoparticles (Au NPs) induced by 1-OHP in the presence of formic acid (FA). Initially, Au NPs were synthesized with citrate as the capping agent and exhibited red color. Subsequently, the addition of FA did not cause aggregation of Au NPs, but a proton transfer process occurred from FA to carboxylic anions on the surface of Au NPs with a decreased zeta potential. The subsequent addition of 1-OHP resulted in a further decreased zeta potential and an intensely hydrophobic environment, which led to a strong and rapid non-crosslinking aggregation of Au NPs within 5 min with the color changing from red to violet blue. Based on this principle, sensitive and selective detection of 1-OHP was achieved. The detection limit was 3.3 nM. Finally, the colorimetric assay was successfully applied to detect 1-OHP in a urine sample. This strategy provides new insights into developing colorimetric methods for on-site and real-time detection of polycyclic aromatic hydrocarbons.

Monodispersed and ultrastable colloidal ZnS nanospheres (NPs) composed of tiny nanoparticles were successfully synthesized by using a limited ligand-induced in situ aggregation strategy. With such a strategy, the whole size as well as the particle size of those ZnS NPs could be tuned simultaneously by appropriately varying the reaction conditions. Three representative ZnS NP samples with different sphere sizes and particle sizes were thus obtained, which were all proven to possess rather large surface areas, robust structures and excellent colloidal stability. Furthermore, the photocatalytic activities of the as-prepared ZnS NPs toward the photodegradation of eosin B, methylene blue and their binary mixture were explored respectively. An interesting size-dependent degradation performance associated with the ZnS NPs was observed in all the photodegradation cases. Finally, their degradation mechanism was fully elucidated according to the control experiments under different atmospheres in combination with the related energy level information. We believe that the control strategy for tuning the fine and whole structures of spherical nanostructures in a synergistic manner together with the structure-dependent photodegradation performance revealed herein will definitely benefit the fabrication of highly efficient photocatalysts as well as the nanocomplexes with hierarchical architectures.

A microarray-format colorimetric biochip was constructed on plastic using two specially-designed DNA hairpin strands as binary probes and a binding-induced conformational switching strategy as the signal generation protocol. Coupled with single- or dual-color staining, we were able to simultaneously detect and quantitate the trace amounts of Pb(2+) and Hg(2+) in various real-world samples.

Platinum (Pt) nanoparticles were electrochemically deposited on multi-walled carbon nanotubes (MWCNTs) through a three-step process, including an electrochemical treatment of MWCNT, electro-oxidation of PtCl4 2− to Pt(IV) complex, and an electro-conversion of Pt(0) on MWCNT. The effect of formation conditions for Pt(IV) complexes on the Pt nanoparticals transformed was investigated. The structure and elemental composition of the resulting Pt/MWCNT electrode were characterized by transmission electron micrograph (TEM) and energy dispersive X-ray spectroscopy (EDX). The electrocatalytic properties of the resulting Pt/MWCNT electrode for methanol oxidation have been investigated. The high electrocatalytic activity and good stability of Pt/MWCNT electrode may be attributed to the high dispersion of platinum nanoparticles and the particular properties of the MWCNT supports.

The direct electrochemistry of hemoglobin (Hb) was studied in a novel all-carbon nanocomposite film of C(60)-MWCNT (MWCNT=multiple-walled carbon nanotube) and compared with that in bare MWCNT film. The heterogeneous electron-transfer rate constant k(s) of Hb/C(60)-MWCNT was determined to be 0.39 s(-1), which is more than one order of magnitude greater than that of Hb/MWCNT (0.03 s(-1)). The significantly accelerated electron-transfer kinetics are attributed to the mediator role played by C(60), which is finely dispersed on the MWCNT surfaces. The excellent stability of Hb/C(60)-MWCNT was established and its potential application towards the electrocatalytic reduction of O(2) was demonstrated.

The electrochemical behavior of a C 60 /MWCNT (multi-walled carbon nanotube) film cast on GC electrode in acetonitrile solution was investigated. Repeated cyclic voltammetric scans transformed the precursor to a C 60 –MWCNT composite film which exhibited reversible electron-transfer reactions and superpose the redox feature of the bare MWCNTs with monotonic charge injection over the whole potential range. This is in contrast to both C 60 film and peapods of C 60 inside carbon nanotubes but resembles the behavior of C 60 dissolved in organic solutions. The formation and structure of the C 60 –MWCNT composite films were studied by UV–Vis, FT-IR, and TEM.

The electrochemical behavior of metallofullerene (Dy@C82) in didodecyldimethylammonium bromide (DDAB) films deposited on glassy carbon, quartz crystal microbalance (QCM) gold crystals, and indium tin oxide (ITO) electrodes in aqueous solution was investigated in detail. Four pairs of reversible redox peaks were observed, and for the first time, these peaks were characterized by vis/NIR spectroscopy. Different from previous fullerene/cationic lipid modified electrodes, one oxidation and three reduction processes were observed. The stability of Dy@C82 and its ions in the film toward air was detected by measuring its cyclic voltammogram after holding the potentials for 10 s, followed by introducing 10 microL of air to the solution. Dy@C82 and its first three anions are stable toward air and water, while some chemical reactions take place when the third anion is further reduced in the film. Dy@C82+ is less stable than Dy@C82- toward water and air. The electrochemical processes were measured in different electrolytes, which showed pronounced anionic dependence on either its cation or anions. The electrochemical processes were also monitored using electrochemical quartz crystal microbalance (EQCM), and from the result a possible electron-transfer mechanism of a Dy@C82/DDAB electrode in aqueous solution was presented. It showed that the anions of Dy@C82 were bound to the DDA+ cation in the film, while the anions of electrolyte diffused into the film to compensate the positive charges when a cation of Dy@C82 was generated.

A new electrochemical route for the synthesis of a hybrid thin film of endohedral metallofullerene (Dy@C82 is used here) and polythiophene is presented, which exploits the unique, compatible redox properties of the couple. The electrochemical response of the resulting Dy@C82/polythiophene film resembles that of Dy@C82 in organic solvents except for the potential peak shifts, but is markedly different from that of a pure metallofullerene solid film. Both the polythiophene backbones and the Dy@C82 moieties appear to retain their individual electrochemical properties in the hybrid film. The film was characterized by UV–visible and Fourier transform infrared absorption spectroscopy, time-of-flight secondary ion mass spectrometry, and scanning electron microscopy. The data suggest that the Dy@C82 molecules have been uniformly dispersed in the polythiophene matrix, forming a compact film. The formation and the electrochemical response of the hybrid film have been systematically studied, refining the viable strategy for the encapsulation of metallofullerenes into conducting polymers.

We report on the recent progress on the preparation and characterization of functional endohedral metallofullerene films. In particular, the wet assembly methods including electrochemical deposition and solution casting have been used for film preparation. Preliminary results on the redox properties and sensor applications of these metallofullerence films are described.

The aqueous electrochemistry of Dy@C 82 films and membrane films of didodecyldimethylammonium bromide (DDAB) encapsulated with Dy@C 82 has been studied systematically. The redox responses of the Dy@C 82 films depend strongly on the supporting electrolytes. In the aqueous solution of tetrabutylammonium bromide, we obtained four cathodic waves at 0.040, −0.40, −1.04, and −1.35 V, and one oxidation wave at +0.31 V. For the membrane films of Dy@C 82 –DDAB film, however, the well-defined redox responses in water are relatively independent of the supporting electrolytes because of the encapsulation and fine dispersion of Dy@C 82 in the DDAB membrane. Reversible reduction and oxidation waves were obtained even in the pH 7.0 buffer solution containing KCl, which is associated with the charge balance of the DDAB ions with the ions of Dy@C 82 . It was found that Dy@C 82 in the DDAB membrane promotes the encapsulation of hemoglobin (Hb) and Hb can catalyze the reduction of Dy@C 82 . Significantly enhanced electrocatalytic reduction of O 2 by Hb in the presence of Dy@C 82 has also been demonstrated. Here Dy@C 82 acts an electron-transfer mediator, which points to the potential application of metallofullerenes in biochemical sensing.

Photoactive fulleropyrrolidine−perylenetetracarboxylic diimide−porphyrin triad (FPP) and its zinc analogue (ZnFPP) with expanded absorptions in the visible spectral region were synthesized. Steady absorption spectra and cyclic voltammetry (CV) measurement showed rather weak electronic interactions among the component chromophores in the ground state within the triads. Preliminary fluorescence measurements indicated the occurrence of a photoinduced electron-transfer process within the triads. These processes can be elicited either in the excited state of the perylenetetracarboxylic diimide chromophore or in the excited state of the porphyrin chromophore. The existence of photoinduced charge-separated states within triads in solution was confirmed by steady-state photolysis in the presence of methyl viologen (MV2+) as a sacrificed electron acceptor and 1-benzyl-1,4-dihydronicotinamide (BNAH) as a sacrificed electron donor. The photovoltaic devices have been fabricated on the basis of the triads and have sho...

We demonstrate a dramatic enhancement of the cathodic photocurrent of a photoelectrochemical (PEC) device based on the Langmuir–Blodgett (LB) film of poly(3-hexylthiophene) (P3HT) by doping with Dy@C 82 , which is attributed to the facile photoinduced electron transfer between P3HT and Dy@C 82 . The photocurrent efficiency of the P3HT/Dy@C 82 PEC device is found to be composition dependent, which is the highest when the molar ratio of P3HT:Dy@C 82 is 20:1. The optimal PEC performance is strongly correlated with the ordered molecular arrangements. A possible mechanism for the cathodic photocurrent generation is proposed and supported by the studies on the bilayer PEC device.

We have successfully constructed photoelectrochemical (PEC) cells based on the Langmuir−Blodgett (LB) films of poly(3-hexylthiophene) (P3HT) doped with Dy@C82. The composite structure is featured by the interaction between Dy@C82 and the thiophene building blocks of P3HT, which take an edge-on arrangement at the air/water interface. The usage of the P3HT−Dy@C82 composite LB films in photoelectrochemical (PEC) cells yields a dramatic enhancement of the cathodic photocurrent, with the power-conversion efficiency (ηe) and quantum yield (Φ) being up to 16-fold and 9-fold higher, respectively, than those of pure P3HT cells. This is attributed to the facile photoinduced electron transfer between P3HT and Dy@C82, which is also revealed by photoluminescence (PL) spectroscopic characterization. The optimum PEC performance is found to be correlated with an ordered film structure as revealed by AFM measurements. The effects of the electron acceptor, bias voltage, light intensity, and number of layers have been studi...

Solution-cast films of the major isomer of Dy@C(82) (Dy@C(82)(I)) have been studied by cyclic voltammetry (CV) in acetonitrile. The films are found to display pronounced and stable redox responses in solution. The reduction/reoxidation processes exhibit large splittings between the first two reduction and reoxidation waves. However, a pair of reversible oxidation and rereduction waves is observed after the reoxidation of a reduced film. The characteristics and the inter-relationship of these waves are uncovered by the CV technique, scanning electron microscopy (SEM), and UV/Vis-NIR spectra. A possible mechanism is proposed for the film electrode processes, which emphasizes the redox-induced structural reorganization of the metallofullerene film by the incorporation and expulsion of electrolyte ions into and out of the film. The influence of the counter ion diffusivity and the ion-pair stability on the electrochemical activity of the metallofullerene film has also been indicated.

Stable Langmuir−Blodgett films of the endohedral metallofullerene Dy@C82 mixed with metallophthalocyanine (MPc = copper tetra-tert-butylphthalocyanine (1) and M octakis(octyloxy)phthalocyanine, M =...

In this paper, the electrochemical and photophysical properties of two well-solubilized monofunctionalized methanofullerene derivatives (TDC60 and TC60) were investigated by cyclic voltammetry, UV−visible absorption, and fluorescence spectroscopic methods. These two methanofullerenes show almost the same electron acceptor properties. The MEH-PPV/methanofullerene blends were made, and it was found that the photoluminescence of MEH-PPV could be quenched more efficiently by TDC60. The two methanofullerenes were used to fabricate organic photovoltaic devices by taking MEH-PPV as the electron donor. Although the photovoltaic properties of the MEH-PPV/methanofullerene devices are better than those of the pristine MEH-PPV, the MEH-PPV/TDC60 device system shows even better performances. Considering the similarities of the structures as well as the electron acceptor abilities, the better performance of the MEH-PPV/TDC60 photovoltaic device should be due to the better compatibility of TDC60 with MEH-PPV, which was ...