Jinfang Zhi

Fabrication of Boron-Doped Diamond Nanorod Forest Electrodes and Their Application in Nonenzymatic Amperometric Glucose Biosensing

A boron-doped diamond nanorod forest (BDDNF) electrode has been fabricated by hot filament chemical vapor deposition (HFCVD) method. This BDDNF electrode exhibits very attractive electrochemical performance compared to conventional planar boron-doped diamond (BDD) electrodes, notably improved sensitivity and selectivity for biomolecule detection. The BDDNF electrode, with the possibility of fabricating a sensitive biosensor for glucose without any catalyst or mediators, shows good activity toward direct detection of glucose by simply putting the bare BDDNF electrode into the glucose solution. Furthermore, the marked selectivity of the BDDNF electrode is very favorable for the determination of glucose in the presence of ascorbic acid (AA) and uric acid (UA). The robust sensitive and selective responses of this nanostructure indicate the promise of this kind of diamond electrode for real applications.

The application of boron-doped diamond electrodes in amperometric biosensors

Boron-doped diamond (BDD) electrodes outperform conventional electrodes in terms of high stability, chemical inertness, wide potential window and low background current. Combining the superior properties of BDD electrodes with the merits of biosensors, such as specificity, sensitivity, and fast response, amperometric biosensors based on BDD electrodes have attracted the interests of many researchers. In this review, the latest advances of BDD electrodes with different surfaces including hydrogen-terminated, oxygen-terminated, metal nanoparticles-modified, amine-terminated, and carboxyl-terminated thin films, and microelectrodes, for the construction of various biosensors or the direct detection of biomolecules were demonstrated. The future trends of BDD electrodes in biosensing were also discussed.

Nanodiamond as the pH‐Responsive Vehicle for an Anticancer Drug

Cis-dichlorodiammineplatinum(II) (CDDP, cisplatin), a widely used anticancer drug, is successfully loaded onto nanodiamond (ND) by adsorption and complexation. The CDDP-ND composite is characterized by IR spectroscopy, atomic absorption spectroscopy, thermogravimetric analysis, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. CDDP is released from the composite in phosphate-buffered saline (PBS) of pH 6.0 at a rate higher than in PBS of pH 7.4. Therefore, it is predicted that the ND vehicle would deliver low concentrations of CDDP in the blood, but release much more drug after integration into the acidic cytoplasm, thereby reducing toxic side effects. The complexation between CDDP and the carboxyl groups on the ND surface is responsible for the pH-responsive release property. The drug released from the composite retains the same cytotoxicity as free CDDP against human cervical cancer cells.

Direct Electrochemistry and Electrocatalytic Activity of Cytochrome c Covalently Immobilized on a Boron-Doped Nanocrystalline Diamond Electrode

Cytochrome c (Cyt c) was covalently immobilized on a boron-doped nanocrystalline diamond (BDND) electrode via surface functionalization with undecylenic acid methyl ester and subsequent removal of the protecting ester groups to produce a carboxyl-terminated surface. Cyt c-modified BDND electrode exhibited a pair of quasi-reversible and well-defined redox peaks with a formal potential (E(0)) of 0.061 V (vs Ag/AgCl) in 0.1 M phosphate buffer solution (pH 7.0) and a surface-controlled process with a high electron transfer constant (ks) of 5.2 +/- 0.6 s(-1). The electrochemical properties of as-deposited and Cyt c-modified boron-doped microcrystalline diamond (BDMD) electrodes were also studied for comparison. Investigation of the electrocatalytic activity of the Cyt c-modified BDND electrode toward hydrogen peroxide (H2O2) revealed a rapid amperometric response (5 s). The linear range of response to H2O2 concentration was from 1 to 450 microM, and the detection limit was 0.7 microM at a signal-to-noise ratio of 3. The stability of the Cyt c-modified BDND electrode, in comparison with that of the BDMD and glassy carbon counterpart electrodes, was also evaluated.

Non-enzymatic glucose detection using as-prepared boron-doped diamond thin-film electrodes

Electrochemical oxidation of glucose in alkaline solution at as-prepared boron-doped microcrystalline diamond (BDMD) and nanocrystalline diamond (BDND) thin-film electrodes is investigated by cyclic voltammetry. The results demonstrate that glucose can be directly oxidized at as-prepared boron-doped diamond (BDD) thin-film electrodes and the curve of the negative scan traces onto the positive scan. The effect of sodium hydroxide concentration on the response of glucose is also studied in the range of 0.02-0.6 M and the optimum concentration of sodium hydroxide is found to be 0.1 M. The voltammetric signal of glucose and the mixture of ascorbic acid (AA) and uric acid (UA) can be observed well-separated at as-prepared BDD thin-film electrodes in 0.1 M sodium hydroxide solution. The peak current is proportional to the glucose concentration in the range 0.25-10 mM with a correlation coefficient of 0.9993 in the presence of AA and UA. Furthermore, the experiment results also show that the non-enzymatic glucose sensor based on as-prepared BDD thin-film electrodes has high sensitivity, good reproducibility and stability.

Fabrication of micropatterned ZnO/SiO2 core/shell nanorod arrays on a nanocrystalline diamond film and their application to DNA hybridization detection

Micropatterned ZnO/SiO2 core/shell nanorod arrays are successfully fabricated on nanocrystalline diamond (NCD) film surfaces, and their performance as a fluorescence signal enhancing platform for DNA hybridization detection is also investigated. The fabrication process, from oriented ZnO nanorod deposition, amine silanation, and attachment of a biofunctional cross-linking molecule to the covalent immobilization of probe oligonucleotides, is defined. X-Ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to characterize ZnO/SiO2 core/shell nanorods. The sequence complementary and stability of the DNA-modified surface are demonstrated in hybridization experiments. The use of ZnO/SiO2 nanorod arrays not only greatly enhances the fluorescence signal collected but also decreases the nonspecific adsorption effect of ZnO nanomaterials after carrying out the hybridization reaction.

Diamond Nanowires: Fabrication, Structure, Properties, and Applications

C(sp(3) )C-bonded diamond nanowires are wide band gap semiconductors that exhibit a combination of superior properties such as negative electron affinity, chemical inertness, high Youngs modulus, the highest hardness, and room-temperature thermal conductivity. The creation of 1D diamond nanowires with their giant surface-to-volume ratio enhancements makes it possible to control and enhance the fundamental properties of diamond. Although theoretical comparisons with carbon nanotubes have shown that diamond nanowires are energetically and mechanically viable structures, reproducibly synthesizing the crystalline diamond nanowires has remained challenging. We present a comprehensive, up-to-date review of diamond nanowires, including a discussion of their synthesis along with their structures, properties, and applications.

Low-temperature and one-step synthesis of rutile TiO2 aqueous sol by heterogeneous nucleation method

A phase-pure rutile TiO(2) aqueous sol has been prepared by heterogeneous nucleation method with an aqueous peroxotitanate solution as a precursor and SnCl(2) as rutile-phase crystalline growth promoter at a temperature as low as 100 °C in one-step process. TEM, XRD and UV-Vis spectra were used to characterize the rutile TiO(2) sol. The results reveal that a pure rutile phase TiO(2) aqueous sol with average particle sizes of around 20 nm has been synthesized, and a transparent film of rutile TiO(2) was also easily prepared by dip-coating method. Formation conditions and a possible mechanism of phase-controlling were investigated. The results show that the presence of the Sn content is essential for the formation of a pure rutile TiO(2) phase at low temperature, which involves a heterogeneous nucleation mechanism.

Large scale fabrication of highly monodispersed rattle-type TiO2@void@SiO2 spheres via synthesis-cum-organization process.

Architected nanostructures with interior space have attracted enormous attention due to both their esthetic beauty and their potential applications. It is a current dream to develop a template-free, one-pot and low-temperature synthetic routes for hetero-architecture in liquid media. In this manuscript, we develop a kind of template-free, low-temperature, and one-pot total synthetic strategy for synthesis of inorganic multi-component hetero-architecture. This synthetic strategy analogous to standard organic reactions used in total synthesis is an important breakthrough in inorganic chemical synthesis. We can achieve 1 kilogram (kg) yield of the TiO(2)@void@SiO(2) core-shell sphere one time by using this synthetic strategy, which may lead to practical applications of the sample. By embodying the new reaction and concept into future investigation, a more mature research field in synthetic architecture of nanomaterials can be anticipated.

Surface functionalization of cubic boron nitride films for biological sensing applications

Surface functionalization and modification scheme of cubic boron nitride (cBN) films deposited by chemical vapor deposition was demonstrated. A homogeneous layer of amino groups was bonded covalently on the B and/or N atoms of cBN surface via a photochemical reaction with allylamine. X-ray photoelectron spectroscopy was carried out to verify comprehensively each stage of the surface modification process. Gold nanoparticles (AuNPs) were self-assembled on the amine-terminated cBN surface, and a dense and well-distributed AuNPs monolayer was obtained. Modification of amine-terminated cBN films with amine-modified DNA probes presents an example of applications as DNA biosensors.