Graphene, emerging as a true 2-dimensional material, has received increasing attention due to its unique physicochemical properties (high surface area, excellent conductivity, high mechanical strength, and ease of functionalization and mass production). This article selectively reviews recent advances in graphene-based electrochemical sensors and biosensors. In particular, graphene for direct electrochemistry of enzyme, its electrocatalytic activity toward small biomolecules (hydrogen peroxide, NADH, dopamine, etc.), and graphenebased enzyme biosensors have been summarized in more detail; Graphene-based DNA sensing and environmental analysis have been discussed. Future perspectives in this rapidly developing field are also discussed.

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Graphene Based Electrochemical Sensors and Biosensors: A Review

Graphene oxide: preparation, functionalization, and electrochemical applications.

https://www.princeton.edu/~cml/assets/pdf/pu_09_XXkang.pdf

Glucose oxidase-graphene-chitosan modified electrode for direct electrochemistry and glucose sensing

A ZnO photocatalyst was hybridized with graphite-like C3N4via a monolayer-dispersed method. After hybridization with C3N4, the photocurrent of ZnO was enhanced by 5 times under UV irradiation and a photocurrent under visible light irradiation was observed. The photocatalytic activity of C3N4/ZnO under UV irradiation was increased by 3.5 times, the visible light photocatalytic activity was generated and the photocorrosion of ZnO was suppressed completely after ZnO was hybridized with C3N4. The enhancement in performance and photocorrosion inhibition under UV irradiation was induced by the high separation efficiency of photoinduced holes from ZnO to the HOMO of C3N4. Under visible light irradiation, the electron excited from the HOMO to the LUMO of C3N4 could directly inject into the CB of ZnO, making C3N4/ZnO present visible light photocatalytic activity. The optimum synergetic effect of C3N4/ZnO was found at a weight ratio of 3%, which corresponded to a monolayer dispersion of C3N4 on the surface of ZnO.

Enhancement of photocurrent and photocatalytic activity of ZnO hybridized with graphite-like C3N4

Review: Carbon nanotube based electrochemical sensors for biomolecules.

Direct electrochemistry of glucose oxidase and biosensing for glucose based on boron-doped carbon nanotubes modified electrode

A simple and ultrasensitive label-free electrochemical impedimetric aptasensor for thrombin based on the cascaded signal amplification was reported. The sandwich system of aptamer/thrombin/aptamer-functionalized Au nanoparticles (Apt-AuNPs) was fabricated as the sensing platform. The change of the interfacial feature of the electrode was characterized by electrochemical impedance analysis with the redox probe [Fe(CN)6]3−/4−. For improving detection sensitivity, the three-level cascaded impedimetric signal amplification was developed: (1) Apt-AuNPs as the first-level signal enhancer; (2) the steric-hindrance between the enlarged Apt-AuNPs as the second-level signal amplification; (3) the electrostatic-repulsion between sodium dodecylsulfate (SDS) stabilized Apt-AuNPs and the redox probe [Fe(CN)6]3−/4− as the third-level signal amplification. Enlargement of Apt-AuNPs integrated with negatively charged surfactant (SDS) capping could not only improve the detection sensitivity of the impedimetric aptasensor fo...

Impedimetric Aptasensor with Femtomolar Sensitivity Based on the Enlargement of Surface-Charged Gold Nanoparticles

A sensitive and stable biosensor based on the direct electrochemistry of glucose oxidase assembled layer-by-layer at the multiwall carbon nanotube-modified electrode.

In this paper, a bifunctional electrochemical biosensor for highly sensitive detection of small molecule (adenosine) or protein (lysozyme) was developed. Two aptamer units for adenosine and lysozyme were immobilized on the gold electrode by the formation of DNA/DNA duplex. The detection of adenosine or lysozyme could be carried out by virtue of switching structures of aptamers from DNA/DNA duplex to DNA/target complex. The change of the interfacial feature of the electrode was characterized by cyclic voltammertic (CV) response of surface-bound [Ru(NH3)6]3+. On the other hand, DNA functionalized Au nanoparticles (DNA-AuNPs) were used to enhance the sensitivity of the aptasensor because DNA-AuNPs modified interface could load more [Ru(NH3)6]3+ cations. Thus, the assembly of two aptamer-contained DNA strands integrated with the DNA−AuNPs amplification not only improves the sensitivity of the electrochemical aptasensor but also presents a simple and general model for bifunctional aptasensor. The proposed apta...

Sensitive Bifunctional Aptamer-Based Electrochemical Biosensor for Small Molecules and Protein

In this work, the dual signal-tagged hairpin structured DNA (dhDNA)-based ratiometric probe was developed by the combination of ferrocene-labeled signal probe (Fc-sP) and methylene blue-modified inner reference probe (MB-rP) in one hairpin-structured DNA. On the basis of this, a high-performance ratiometric electrochemical method was proposed for biomarker detection. In contrast to the conventional ratiometric electrochemical probe, this dhDNA ratiometric probe integrated sP and rP into one structure, which ensured the completely same modification condition and the interdependence of sP and rP on one sensing interface. As a result, the dhDNA ratiometric probe possesses a stronger ability to eliminate the disturbance of environmental change, which was proven by the fact that the changes of the surface roughness and pH value had no significant effects on the reproducibility and stability of the sensor. Moreover, in the proposed strategy, the initial ratio responses of Fc-sP to MB-rP ((IFc-sP/IMB-rP)0) are c...

Chunyan Deng

Papers

Direct electrochemistry of glucose oxidase and biosensing for glucose based on boron-doped carbon nanotubes modified electrode

Impedimetric Aptasensor with Femtomolar Sensitivity Based on the Enlargement of Surface-Charged Gold Nanoparticles

A sensitive and stable biosensor based on the direct electrochemistry of glucose oxidase assembled layer-by-layer at the multiwall carbon nanotube-modified electrode.

Sensitive Bifunctional Aptamer-Based Electrochemical Biosensor for Small Molecules and Protein

High-Performance Ratiometric Electrochemical Method Based on the Combination of Signal Probe and Inner Reference Probe in One Hairpin-Structured DNA