Dan Shan

Single-walled carbon nanotubes noncovalently functionalized by ruthenium(II) complex tagged with pyrene: electrochemical and electrogenerated chemiluminescence properties.

Ru being served: A pyrene-Ru/SWCNT nanohybrid was formed through noncovalent π-π stacking interactions (see figure). After oxidative treatment, the pyrene-Ru/SWCNT-functionalized Pt electrode achieved a highly reversible redox process and exhibited excellent electrogenerated chemiluminescence behavior.

Bioinspired polydopamine as the scaffold for the active AuNPs anchoring and the chemical simultaneously reduced graphene oxide: characterization and the enhanced biosensing application.

We report here an efficient approach to enhance the performance of biosensing platform based on graphene or graphene derivate. Initially, graphene oxides (GO) nanosheets were reduced and surface functionalized by one-step oxidative polymerization of dopamine in basic solution at environment friendly condition to obtain the polydopamine (Pdop) modified reduced graphene oxides (PDRGO). The bioinspired surface was further used as a support to anchor active gold nanoparticles (AuNPs). The morphology and structure of the as-prepared AuNPs/PDRGO nanocomposite were investigated by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR). Electrochemical studies demonstrate that the as-prepared AuNPs/PDRGO hybrid materials possess excellent electrochemical properties and electrocatalytic activity toward the oxidation of NADH at low potential (0.1 V vs. SCE) with the fast response (15s) and the broad linear range (5.0 × 10(-8)-4.2 × 10(-5)M). Thus, this AuNPs/PDRGO nanocomposite can be further used to fabricate a sensitive alcohol biosensor using alcohol dehydrogenase (ADH), by simply incorporating the specific enzyme within the composite matrix with the aid of chitosan (Chit).

TiO2 nanocrystals electrochemiluminescence quenching by biological enlarged nanogold particles and its application for biosensing

Electrochemiluminescence (ECL) of TiO(2) nanocrystals with different crystal styles modified fluorine-doped tin oxide (FTO) electrode was investigated in H(2)O(2) solution. The amorphous TiO(2) nanospheres were facilely synthesized by the hydrothermal and condensation method. Crystal TiO(2), namely anatase and rutile, were prepared by calcination of the amorphous TiO(2) nanospheres at 450 and 800°C, respectively. The transmission electron microscope (TEM) and electron diffraction pattern were used to characterize the obtained TiO(2) nanoparticles morphology and the corresponding crystal styles. The electrochemical and ECL behaviors were investigated by cyclic voltammetry. The ECL quenching was observed by introduction of gold nanoparticles. Based on the quenching effect, a sensitive glucose ECL biosensor as a model was fabricated by in-situ growing-up gold seeds in AuCl(4)(-) solution induced by biologically generated H(2)O(2). The linear range to detect glucose is from 5.0×10(-7)M to 4.0×10(-3)M with the limit of detection of 2.5×10(-7)M.

Sensitive electrochemical detection of NADH and ethanol at low potential based on pyrocatechol violet electrodeposited on single walled carbon nanotubes-modified pencil graphite electrode.

In this work, the electrodeposition of pyrocatechol violet (PCV) was initially investigated by the electrochemical surface plasmon resonance (ESPR) technique. Subsequently, PCV was used as redox-mediator and was electrodeposited on the surface of pencil graphite electrode (PGE) modified with single-wall carbon nanotubes (SWCNTs). Owing to the remarkable synergistic effect of SWCNTs and PCV, PGE/SWCNTs/PCV exhibited excellent electrocatalytic activity towards dihydronicotinamide adenine dinucleotide (NADH) oxidation at low potential (0.2V vs. SCE) with fast amperometric response (<10s), broad linear range (1.3-280 μM), good sensitivity (146.2 μA mM(-1)cm(-2)) and low detection limit (1.3 μM) at signal-to-noise ratio of 3. Thus, this PGE/SWCNTs/PCV could be further used to fabricate a sensitive and economic ethanol biosensor using alcohol dehydrogenase (ADH) via a glutaraldehyde/BSA cross-linking procedure.

Biosensing platform based on graphene oxide via self-assembly induced by synergic interactions

A novel self-assembled glucose biosensor based on graphene oxide (GO) was constructed by using 1-pyrenebutyric acid-N-hydroxysuccinimide ester (PANHS) as linking molecular. The stepwise self-assembly process was performed for PANHS anchoring in N,N-dimethylformamide (DMF) solvent and the further glucose oxidase (GOD) binding in aqueous solution, respectively. The molecular interactions and the morphologic properties were characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electronic microscopy (FESEM), and atomic force microscopy (AFM). In addition, the quantitative loadings of anchored PANHS and GOD were well elucidated by surface plasmon resonance (SPR) measurements. The obtained novel glucose sensor exhibited satisfactory analytical performance to glucose: wide linear range (4.0×10(-6) to 4.4×10(-3) M), fast response (10s), high sensitivity (40.5±0.4 mA M(-1) cm(-2)), and low detection limit (2 μM, S/N=3). Furthermore, the biosensor exhibited excellent long-term stability and satisfactory reproducibility.

Enhanced solid-state electrochemiluminescence of Ru(bpy)32+ immobilized on a laponite gel-state network and its glucose biosensing application

A novel laponite network thin film (denoted as laponitegel-film) was prepared by casting a laponite suspension with salt onto the surface of a glassy carbon electrode (GCE) to incorporate Ru(bpy)32+. The resultant Ru(bpy)32+-laponitegel-film/GCE presented significantly enhanced electrochemiluminescence (ECL) behavior. Thus, a glucose ECL biosensor was developed with a good performance.

Mass effect of redox reactions: A novel mode for surface plasmon resonance-based bioanalysis.

The pursuit of more specific and sensitive response is a perpetual goal for modern bioassays. This work proposed a novel label-free strategy about redox-related mass effect based on the surface plasmon resonance (SPR) technique for ultrasensitive determination of DNA. The protocol starts with the modification of SPR gilded disk with the capture DNA (cDNA). After the conjugation of immobilized cDNA with the target DNA (tDNA), the hybridization chain reaction was triggered by the introduction of mutual partial complementary primers to elongate the terminal into a nanoscale duplex. As it is reported that porphyrin could intercalate into the grooves of the double-stranded DNA (dsDNA) scaffold, multiple positive-charged Fe(III)meso-tetra(N-methyl-4-pyridyl) porphine (FeTMPyP) with symmetric structure were uptaken for in situ formation of porphyrin-dsDNA complex. Given FeTMPyP a highly efficient catalysis for the peroxide reduction, its presence as a biomimetic cofactor was validated via circular dichroism and UV-vis spectroscopy, demonstrating a tight binding as well as high catalytic activity and stability. Using 4-chloro-1-naphthol as a proton donor, the catalytic reduction of H2O2 would oxidize it into insoluble benzo-4-chloro-hexadienone, which simultaneously deposited on the heterogeneous interface, leading to a significant amplification in both SPR response and topological height profile. The signal increment was proportional to the concentration of tDNA, thus an ultrasensitive SPR-based DNA assay was developed with a linear range over four orders of magnitudes and a sub-femtomolar detection limit of 0.73 fM. The developed methodology exemplifies a different way of thinking about mass-sensing modes, extending conventional SPR-based DNA analysis to relevant biomedical applications.