Qiyi Lu

Overoxidized polyimidazole/graphene oxide copolymer modified electrode for the simultaneous determination of ascorbic acid, dopamine, uric acid, guanine and adenine

In the present work, a novel strategy based on overoxidized polyimidazole (PImox) and graphene oxide (GO) copolymer modified electrode was proposed for the simultaneous determination of ascorbic acid (AA), dopamine (DA), uric acid (UA), guanine (G) and adenine (A). The copolymer was characterized by the scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). Due to the synergistic effects between PImox and GO, the proposed electrode exhibited excellent electrochemical catalytic activities and high selectivity and sensitivity toward the oxidation of AA, DA, UA, G and A. The peak separations between AA and DA, AA and UA, UA and G, and G and A were 140 mV, 200 mV, 380 mV and 300 mV, respectively. The linear response ranges for AA, DA, UA, G and A were 75-2275 μM, 12-278 μM, 3.6-249.6 μM, 3.3-103.3 μM and 9.6-215 μM, respectively, and corresponding detection limits were 18 μM, 0.63 μM, 0.59 μM, 0.48 μM and 1.28 μM.

A signal-on electrochemiluminescence biosensor for detecting Con A using phenoxy dextran-graphite-like carbon nitride as signal probe.

A novel signal-on electrochemiluminescence (ECL) biosensor for detecting concanavalin A (Con A) was fabricated with phenoxy dextran-graphite-like carbon nitride (DexP-g-C3N4) as signal probe. In this construction strategy, the nanocomposites of three-dimensional graphene and gold nanoparticles (3D-GR-AuNPs) were used as matrix for high loading of glucose oxidase (GOx), which served as recognition element for bounding Con A. Con A further interacted with DexP-g-C3N4 through a specific carbohydrate-Con A interaction to achieve a sandwiched scheme. With the increase of Con A incubated onto the electrode, the ECL signal resulted from DexP-g-C3N4 would enhance, thus achieving a signal-on ECL biosensor for Con A detection. Due to the integration of the virtues of 3D-GR-AuNPs and the excellent ECL performance of DexP-g-C3N4, the prepared biosensor exhibits a wide linear response range from 0.05 ng/mL to 100 ng/mL and a low detection limit of 17 pg/mL (S/N=3).

An electrogenerated chemiluminescence sensor based on gold nanoparticles@C60 hybrid for the determination of phenolic compounds

This paper described a novel strategy for the construction of an electrogenerated chemiluminescence (ECL) sensor based on gold nanoparticles@C60 (AuNPs@C60) hybrid for detecting phenolic compounds. First, C60 was functionalized with l-cysteine. Subsequently, with C60 as the core, gold nanoparticles (AuNPs) are synthesized and grown through an in situ reduction method in the presence of ascorbic acid (AA). The resulted flowerlike AuNPs@C60 nanoparticles were modified onto the glassy carbon electrode to achieve the sensor (AuNPs@C60/GCE). Here, l-cysteine not only can improve the biocompatibility and hydrophilicity of C60 but also can enhance the electrogenerated chemiluminescence (ECL) of peroxydisulfate system. Furthermore, both AuNPs and C60 are also beneficial to the ECL of the peroxydisulfate system. Due to the combination of l-cysteine, AuNPs and C60, the proposed ECL sensor exhibited an excellent analytical performance. Under an optimum condition, the ECL intensity increased linearly with phenolic compounds. The linear ranges of 6.2 × 10(-8)-1.2 × 10(-4)M, 5.0 × 10(-8)-1.1 × 10(-4)M and 5.0 × 10(-8)-1.1 × 10(-4)M were obtained for catechol (CC), hydroquinone (HQ) and p-cresol (PC), respectively, and the detection limits were 2.1 × 10(-8)M, 1.5 × 10(-8)M and 1.7 × 10(-8)M, respectively. The AuNPs@C60 hybrid might hold a new opportunity to develop an ECL sensor.

Electrochemical sensor based on overoxidized dopamine polymer and 3,4,9,10-perylenetetracarboxylic acid for simultaneous determination of ascorbic acid, dopamine, uric acid, xanthine and hypoxanthine

A novel electrode based on 3,4,9,10-perylenetetracarboxylic acid (PTCA) and overoxidized dopamine polymer (PDAox) was developed for the simultaneous determination of ascorbic acid (AA), dopamine (DA), uric acid (UA), xanthine (XN) and hypoxanthine (HXN). The developed sensors exhibited an excellent catalytic activity, high sensitivity and good selectivity toward the oxidation of AA, DA, UA, XN and HXN. Scanning electron microscopy (SEM), cyclic voltammetry (CV), different pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) were employed to characterize the sensor. The peak separations between AA–DA, DA–UA, UA–XN and XN–HXN were large, up to 0.15, 0.18, 0.37 and 0.4 V, respectively. The calibration curves for AA, DA, UA, XN and HXN were obtained in the ranges of 76 μM to 3.9 mM, 0.60 to 253 μM, 1.8 to 238 μM, 5.1 to 289 μM and 3.8 to 293 μM with detection limits (S/N = 3) of 25.3 μM, 0.20 μM, 0.60 μM, 1.7 μM and 1.3 μM, respectively. The integration of PDAox and PTCA in the sensor opens up a facile and promising method for the simultaneous determination of above five substances.

Electrochemiluminescence sensor for dopamine with a dual molecular recognition strategy based on graphite-like carbon nitride nanosheets/3,4,9,10-perylenetetracarboxylic acid hybrids

Graphite-like carbon nitride nanosheets/3,4,9,10-perylenetetracarboxylic acid hybrids (g-C3N4 NSs–PTCA) were synthesized via π–π conjugate action. Based on novel dual molecular specific recognition of oxyethyl groups to diol and carboxyl to amine groups, a signal-on electrochemiluminescence (ECL) sensor for dopamine (DA) was constructed utilizing g-C3N4 NSs–PTCA as asignal probe and K2S2O8 as a coreactant. Under the optimal conditions, the prepared ECL sensor presented a response to DA with a linear range from 6.0 pM to 30.0 nM. The detection limit (LOD) and limit of quantification (LOQ) of the sensor were 2.4 pM and 7.9 pM, respectively. The g-C3N4 NSs–PTCA signal probe coupling with a novel dual molecular recognition strategy would provide a promising ECL sensing platform for detecting DA sensitively and selectively.

Conjugated polymer dots/oxalate anodic electrochemiluminescence system and its application for detecting melamine

In this work, the anodic electrochemiluminescence (ECL) behavior of water-soluble poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO), is firstly studied with Na2C2O4 as a coreactant using cyclic voltammetry and ECL measurements. The possible anodic ECL mechanism of PFO–C2O42− system is proposed. Based on the fact that the melamine could efficiently quench the ECL signal of the PFO–C2O42− system, a new ECL sensing method for melamine was developed with a wide linear range from 9.0 × 10−11 to 1.1 × 10−8 M. Furthermore, the sensor exhibited high sensitivity and good stability. Due to the excellent ECL behavior, the PFO–C2O42− system could be a promising platform for constructing ECL sensors.

An electrogenerated chemiluminescent biosensor based on a g-C3N4–hemin nanocomposite and hollow gold nanoparticles for the detection of lactate

In this article, a new electrochemiluminescent (ECL) biosensor based on a g-C3N4–hemin nanocomposite and hollow gold nanoparticles (HGNPs) was constructed to detect lactate. Firstly, the g-C3N4 nanosheets were prepared through ultrasonication-assisted liquid exfoliation of bulk g-C3N4, which was obtained through polymerizing melamine under 600 °C. Then, the nanocomposites of g-C3N4 nanosheets and hemin were prepared to modify a glassy carbon electrode. Subsequently, HGNPs were self-assembled onto the electrode for adsorbing lactate oxidase to achieve a lactate biosensor. Due to the excellent catalytic effect of g-C3N4–hemin and HGNPs on the luminol/H2O2 ECL system, the as-prepared biosensor exhibited a good response performance to lactate with a linear range of 1.7 × 10−8 to 5.0 × 10−4 M and a detection limit of 5.5 × 10−9 M. In addition, the prepared ECL biosensor exhibited satisfying reproducibility and stability. The g-C3N4–hemin nanocomposite might have great potential application in a luminol/H2O2 ECL system.

Cathodic electrochemiluminescence behavior of an ammonolysis product of 3,4,9,10-perylenetetracarboxylic dianhydride in aqueous solution and its application for detecting dopamine

The cathodic electrochemiluminescence (ECL) behavior of the ammonolysis product of 3,4,9,10-perylenetetracarboxylic dianhydride (PTC–NH2) in aqueous solution with K2S2O8 as the co-reactant has been, for the first time reported, in this paper. The possible mechanisms have been investigated. Based on the fact that dopamine (DA) can efficiently quench the ECL intensity of PTC–NH2, DA was chosen as a template to investigate the application of PTC–NH2–S2O82− system in the sensor field. Under the optimal conditions, we achieved the detection of DA with the detection limit of 1.6 × 10−9 M. Due to the excellent ECL behavior, PTC–NH2 could be a new class of promising material for the construction of ECL sensors.

A solid-state electrochemiluminescent sensor based on C60/graphite-like carbon nitride nanosheet hybrids for detecting melamine

C60/graphite-like carbon nitride nanosheet (C60/g-C3N4 NS) hybrids were prepared by a simple π–π interaction, and used to construct a solid state electrochemiluminescence (ECL) sensor. Based on the fact that melamine could efficiently quench the ECL intensity of g-C3N4 NS, such a sensor achieved detection of melamine. The possible quenching mechanisms were discussed. Due to the combination of the excellent ECL behavior of g-C3N4 NS with the outstanding electronic conductivity of C60, the prepared sensor exhibited a response for melamine with a wide linear range of 5.0 × 10−13 to 2.7 × 10−11 M and 2.7 × 10−11 to 1.9 × 10−8 M. The detection limit was 1.3 × 10−13 M. In this work, the linear range of melamine was improved by six orders of magnitude and the detection limit as low as sub-picomolar. Such a construction strategy provided a simple, sensitive, low-cost and green detection method for melamine.