Since the early 70s electrochemistry has been used as a powerful analytical technique for monitoring electroactive species in living organisms. In particular, after extremely rapid evolution of new micro and nanotechnology it has been established as an invaluable technique ranging from experiments in vivo to measurement of exocytosis during communication between cells under in vitro conditions. This review highlights recent advances in the development of electrochemical sensors for selective sensing of one of the most important neurotransmitters—dopamine. Dopamine is an electroactive catecholamine neurotransmitter, abundant in the mammalian central nervous system, affecting both cognitive and behavioral functions of living organisms. We have not attempted to cover a large time-span nor to be comprehensive in presenting the vast literature devoted to electrochemical dopamine sensing. Instead, we have focused on the last five years, describing recent progress as well as showing some problems and directions for future development.

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New trends in the electrochemical sensing of dopamine.

Square wave voltammetry (SWV) has been widely used in the development of electrochemical sensors and biosensors in recent years due to its high selectivity and sensitivity. It is of great interest and importance to rapidly and sensitively detect disease-related biomarkers, environmental pollutants (e.g., heavy metals and other chemical contaminants), which are severely detrimental to human and animal life and the environment as a whole. Further, efficacious sensing is required for the detection of food resident contaminants (e.g., bacteria, viruses and parasites) and for the verification of the therapeutic ingredients of dietary supplements. Enzyme kinetics is another interesting domain that employs SWV as an effective analytical tool for the mechanistic study of enzyme reactions. The aim of this paper is to provide a comprehensive review of the electrochemical SWV method and its significant applications in sensing and biosensing spanning various fields such as diagnosis, environmental and food analysis and enzyme kinetics. The development of novel and improved electrode surfaces and nanomaterials introduces the possibility of sensors and biosensors that will exhibit even higher sensitivity, with SWV serving as an ideal methodology for its optimization. Concurrent with a better understanding of electrochemistry and life sciences, sensors and biosensors based on SWV have the potential to serve as next generation point-of-care diagnostic devices, as well as highly sensitive and selective detectors for food/environmental monitoring and enzyme studies.

Electrochemical sensing and biosensing based on square wave voltammetry

Nanostructured SERS-electrochemical biosensors for testing of anticancer drug interactions with DNA.

In this work, a novel fluorescence resonance energy transfer (FRET)-based ratiometric fluorescent probe, carbon dots-gold nanoclusters hybrid (CDots-AuNCs), was fabricated for selective, sensitive and reliable sensing of dopamine (DA). This FRET probe is comprised of a two-fluorophore, where carbon dots (CDots) serve as the energy donor and gold nanoclusters (AuNCs) as the acceptor, with dual emission peaks at 420 nm and 610 nm under a single excitation wavelength of 380 nm. The addition of DA to this probe solution resulted in the fluorescence at 610 nm quenching, while the blue fluorescence at 420 nm recovering. By monitoring the change of ratiometric fluorescent intensity at 420 and 610 nm, the DA could be detected with the range from 5 to 180 nM and a limit of detection around 2.9 nM. Finally, the developed sensing method was successfully applied to DA determination in serum samples with satisfactory recoveries in the range of 95%–105%.

Highly sensitive and selective dual-emission ratiometric fluorescence detection of dopamine based on carbon dots-gold nanoclusters hybrid

This review represents a comprehensive attempt to summarize and discuss various sensing applications of iron oxide nanoparticles (NPs), which have attracted a great deal of attention over recent years because of their easy preparation, biocompatibility, nontoxicity, and broad range of biomedical applications. We review the application potential of nanomagnetite based amperometic sensors possessing an intrinsic enzyme mimetic activity similar to that found in natural peroxidases. In addition, we discuss the properties and applications of enzymatic sensors exploiting glucose oxidase, tyrosinase, and other enzymes for sensing a variety of important biomedical species. Among iron oxide-based nanocomposites, we highlight the use of Fe3O4@Au hybrids for designing new electrochemical aptasensors with unique versatility for binding diverse targets, including proteins and peptides. Similarly, sensing applications of composites of iron oxide NPs with graphene derivatives and carbon nanotubes are reviewed. A large p...

Nanocrystalline Iron Oxides, Composites, and Related Materials as a Platform for Electrochemical, Magnetic, and Chemical Biosensors

A tyrosinase biosensor based on Fe3O4-chitosan nanocomposite has been developed for the amperometric detection of dopamine by the biocatalytically liberated dopaquinone at −0.25V vs. saturated calomel electrode. The obtained bio-nanoparticles, which were attached to the surface of a glassy carbon electrode (GCE), showed excellent electrochemical characteristics and at the same time acted as mediator to transfer electrons between the enzyme and the electrode. Under optimal conditions, the biosensor showed broad linear response of 2.0×10 −8 to 7.5×10 −5 mol L −1 , with the low detection limit of 6.0×10 −9 mol L −1 and the high sensitivity of 46 μA/mM for the determination of dopamine in the presence of ascorbic acid. Such tyrosinase biosensor exhibits great promise for rapid, simple and cost-effective analysis of dopamine in the samples. This immobilization approach effectively improved the stability of the electron transfer mediator and is promising for construction of biosensor and bioelectronic devices.

http://www.nwpii.com/ajbms/papers/AJBMS_2010_3_10.pdf

Detection of Dopamine Based on Tyrosinase-Fe3O4 Nanoparticles-chitosan Nanocomposite Biosensor

Oxidative DNA damage is one of the most critical factors implicated in carcinogenesis and other disorders. Sensitive and reliable detection of oxidative DNA damage remains a significant challenge. In this work, a sensitive electrochemical biosensor based on a double stranded DNA immobilized on a xanthine oxidase (XOD)-modified glassy carbon electrode (denoted as DNA–XOD/GCE) has been developed to explore the rapid detection of DNA damage. Co(bpy)33+ was used as a redox indicator to monitor DNA damage induced by hydroxyl radical ( OH), which is a reactive oxygen species generated by a XOD-catalyzed Fenton reaction in xanthine/FeSO4 system. The produced OH was validated by UV–vis spectroscopy. The electrochemical behavior of the underlying electrodes was characterized by square wave voltammetry and electrochemical impedance spectroscopy. Optimization of the concentrations of FeSO4 and XA, and the incubation time in terms of DNA damage was explored. Moreover, the protection of DNA from damage by antioxidants, such as ascorbic acid, aloe-emodin, and rutin was investigated. The conclusions demonstrate that the proposed electrochemical method is expected to be of use in further application for DNA damage studies.

An electrochemical biosensor for the rapid detection of DNA damage induced by xanthine oxidase-catalyzed Fenton reaction

We report on a biosensor for the electrochemical detection of the damage of DNA and of antioxidant protecting DNA. The biosensor was constructed by co-immobilization of DNA and glucose oxidase (GOx) on a glassy carbon electrode. Under aerobic conditions, GOx catalyzes the oxidation of glucose, and the hydrogen peroxide produced reacts with ferrous ions in a Fenton-type reaction to generate hydroxy radical. This was validated by UV–vis spectroscopy. The hydroxy radical can cause serious oxidative damage to DNA, and this can be detected by square wave voltammetry of the electroactive indicator Co(bpy)
 3
 3+
 . The effects of pH value, incubation time, and the concentration of glucose and ferrous ion were optimized. The effects of the antioxidants ascorbic acid and aloe emodin on DNA damage were also investigated within the concentration range from 0.05 to 200 μM. This work provides an in-vitro model system to mimic the processes in oxidative DNA damage by a simple electrochemical approach.

Electrochemical detection of in situ DNA damage induced by enzyme-catalyzed Fenton reaction. Part I: in phosphate buffer solution

A hydrophobic room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), was applied as nonaqueous solvent for the generation of hydroxy radical (•OH) through glucose oxidase-catalyzed Fenton reaction. The enzyme catalyzes the oxidation of glucose, and the produced H2O2 further reacts with transition metal ions, generating hydroxyl radicals. They attacked DNA and led its damage. This was detected by square wave voltammetry (SWV) of the electroactive indicator Co(bpy)
 3
 3+
 . It bound more strongly to intact DNA, and the SWV peak currents decreased at the potential of 0.064 V when DNA was damaged. The experimental results testified that the antioxidants, ascorbic acid, aloe-emodin and rutin, inhibited oxidative DNA damage by hydroxyl radicals. The method is promising for rapid, sensitive, and inexpensive detection of DNA damage.

Yang Chen

Papers

Detection of Dopamine Based on Tyrosinase-Fe3O4 Nanoparticles-chitosan Nanocomposite Biosensor

An electrochemical biosensor for the rapid detection of DNA damage induced by xanthine oxidase-catalyzed Fenton reaction

Electrochemical detection of in situ DNA damage induced by enzyme-catalyzed Fenton reaction. Part I: in phosphate buffer solution

Electrochemical detection of in situ DNA damage induced by enzyme-catalyzed Fenton reaction. Part II in hydrophobic room temperature ionic liquid