Limits...
Nanomaterial-based electrochemical sensing of neurological drugs and neurotransmitters.

Sanghavi BJ, Wolfbeis OS, Hirsch T, Swami NS - Mikrochim Acta (2014)

Bottom Line: This results in tremendous gains in terms of sensitivity, selectivity and versatility.We focus on understanding how specific nano-sized modifiers may be applied to influence the electron transfer event to result in gains in sensitivity, selectivity and versatility of the detection system.Figureᅟ

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, VA 22904 USA.

ABSTRACT

Nanomaterial-modified detection systems represent a chief driver towards the adoption of electrochemical methods, since nanomaterials enable functional tunability, ability to self-assemble, and novel electrical, optical and catalytic properties that emerge at this scale. This results in tremendous gains in terms of sensitivity, selectivity and versatility. We review the electrochemical methods and mechanisms that may be applied to the detection of neurological drugs. We focus on understanding how specific nano-sized modifiers may be applied to influence the electron transfer event to result in gains in sensitivity, selectivity and versatility of the detection system. This critical review is structured on the basis of the Anatomical Therapeutic Chemical (ATC) Classification System, specifically ATC Code N (neurotransmitters). Specific sections are dedicated to the widely used electrodes based on the carbon materials, supporting electrolytes, and on electrochemical detection paradigms for neurological drugs and neurotransmitters within the groups referred to as ATC codes N01 to N07. We finally discuss emerging trends and future challenges such as the development of strategies for simultaneous detection of multiple targets with high spatial and temporal resolutions, the integration of microfluidic strategies for selective and localized analyte pre-concentration, the real-time monitoring of neurotransmitter secretions from active cell cultures under electro- and chemotactic cues, aptamer-based biosensors, and the miniaturization of the sensing system for detection in small sample volumes and for enabling cost savings due to manufacturing scale-up. The Electronic Supporting Material (ESM) includes review articles dealing with the review topic in last 40 years, as well as key properties of the analytes, viz., pKa values, half-life of drugs and their electrochemical mechanisms. The ESM also defines analytical figures of merit of the drugs and neurotransmitters. The article contains 198 references in the main manuscript and 207 references in the Electronic Supporting Material. Figureᅟ

No MeSH data available.


Related in: MedlinePlus

(α) Schematic illustration of the stepwise sensor fabrication process (electrodeposition) [103]. (β) Schematic illustration of the stepwise sensor fabrication process (immobilization) [85]. (γ) Schematic illustration of the stepwise sensor fabrication process (nafion coated electrode) [143]
© Copyright Policy - OpenAccess
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4281370&req=5

Fig9: (α) Schematic illustration of the stepwise sensor fabrication process (electrodeposition) [103]. (β) Schematic illustration of the stepwise sensor fabrication process (immobilization) [85]. (γ) Schematic illustration of the stepwise sensor fabrication process (nafion coated electrode) [143]

Mentions: DNA has also been employed for DA detection in synergism with AuNPs. A sensor based on a nano-Au/DNA/nano-Au/poly (SFR) composite for simultaneous determination of dopamine, uric acid, guanine, and adenine was reported [85]. A film of poly-safranine T (SFR) was deposited on a GCE surface by electropolymerization. The electrode was immersed into colloidal solutions of AuNPs which was then transferred into a ds-DNA solution, immersed and then rinsed with water and tris-buffer to remove non-adsorbed DNA. Finally, the electrode modified with three-dimensionally distributed AuNPs was obtained by re-immerse the DNA-modified electrode into a colloidal gold solution. The nano-Au/DNA/nano-Au/poly (SFR)/GCE is illustrated in Fig. 9β. The poly (SFR) monolayer not only produced a catalytic effect but also provided a template, onto which AuNPs were anchored, generating a 2D array of nano-gold-modified electrodes. The second layer of AuNPs on the electrode formed a 3D distribution via DNA linkages. Reaction rates were improved because of the combination of catalytic effects of poly (SFR) and sandwiched AuNPs. Impedance was measured at frequencies ranging from 10-2 to 106 Hz and a formal potential of 0.14 V. A small semicircle was observed in the Nyquist plot of the bare GCE, as shown in Fig. 6γ (curve a). The interfacial Rct corresponding to the semicircle diameters increased because the poly (SFR) perturbed the interfacial electron transfer rates between the electrode and the electrolyte solution (curve b). In the next step, electron transfer occurred more easily because the nanometer-sized AuNPs acted as conducting wires or electron-conducting tunnels. As a result, Rct decreased after the adsorption of nanogold on the surface of the electrode (curve c). The increased Rct observed after DNA immobilization was ascribed to the repulsion of negatively charged DNA phosphate skeletons. Rct obviously decreased again after immersion into the colloidal gold solution for a second time, yielding a value lower than that of the AuNP monolayer-modified electrode. The LOD for DA was 0.2 nM which indicates that the method is sensitive. However, the electrode preparation was tedious and took almost 12 h.Fig. 9


Nanomaterial-based electrochemical sensing of neurological drugs and neurotransmitters.

Sanghavi BJ, Wolfbeis OS, Hirsch T, Swami NS - Mikrochim Acta (2014)

(α) Schematic illustration of the stepwise sensor fabrication process (electrodeposition) [103]. (β) Schematic illustration of the stepwise sensor fabrication process (immobilization) [85]. (γ) Schematic illustration of the stepwise sensor fabrication process (nafion coated electrode) [143]
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4281370&req=5

Fig9: (α) Schematic illustration of the stepwise sensor fabrication process (electrodeposition) [103]. (β) Schematic illustration of the stepwise sensor fabrication process (immobilization) [85]. (γ) Schematic illustration of the stepwise sensor fabrication process (nafion coated electrode) [143]
Mentions: DNA has also been employed for DA detection in synergism with AuNPs. A sensor based on a nano-Au/DNA/nano-Au/poly (SFR) composite for simultaneous determination of dopamine, uric acid, guanine, and adenine was reported [85]. A film of poly-safranine T (SFR) was deposited on a GCE surface by electropolymerization. The electrode was immersed into colloidal solutions of AuNPs which was then transferred into a ds-DNA solution, immersed and then rinsed with water and tris-buffer to remove non-adsorbed DNA. Finally, the electrode modified with three-dimensionally distributed AuNPs was obtained by re-immerse the DNA-modified electrode into a colloidal gold solution. The nano-Au/DNA/nano-Au/poly (SFR)/GCE is illustrated in Fig. 9β. The poly (SFR) monolayer not only produced a catalytic effect but also provided a template, onto which AuNPs were anchored, generating a 2D array of nano-gold-modified electrodes. The second layer of AuNPs on the electrode formed a 3D distribution via DNA linkages. Reaction rates were improved because of the combination of catalytic effects of poly (SFR) and sandwiched AuNPs. Impedance was measured at frequencies ranging from 10-2 to 106 Hz and a formal potential of 0.14 V. A small semicircle was observed in the Nyquist plot of the bare GCE, as shown in Fig. 6γ (curve a). The interfacial Rct corresponding to the semicircle diameters increased because the poly (SFR) perturbed the interfacial electron transfer rates between the electrode and the electrolyte solution (curve b). In the next step, electron transfer occurred more easily because the nanometer-sized AuNPs acted as conducting wires or electron-conducting tunnels. As a result, Rct decreased after the adsorption of nanogold on the surface of the electrode (curve c). The increased Rct observed after DNA immobilization was ascribed to the repulsion of negatively charged DNA phosphate skeletons. Rct obviously decreased again after immersion into the colloidal gold solution for a second time, yielding a value lower than that of the AuNP monolayer-modified electrode. The LOD for DA was 0.2 nM which indicates that the method is sensitive. However, the electrode preparation was tedious and took almost 12 h.Fig. 9

Bottom Line: This results in tremendous gains in terms of sensitivity, selectivity and versatility.We focus on understanding how specific nano-sized modifiers may be applied to influence the electron transfer event to result in gains in sensitivity, selectivity and versatility of the detection system.Figureᅟ

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, VA 22904 USA.

ABSTRACT

Nanomaterial-modified detection systems represent a chief driver towards the adoption of electrochemical methods, since nanomaterials enable functional tunability, ability to self-assemble, and novel electrical, optical and catalytic properties that emerge at this scale. This results in tremendous gains in terms of sensitivity, selectivity and versatility. We review the electrochemical methods and mechanisms that may be applied to the detection of neurological drugs. We focus on understanding how specific nano-sized modifiers may be applied to influence the electron transfer event to result in gains in sensitivity, selectivity and versatility of the detection system. This critical review is structured on the basis of the Anatomical Therapeutic Chemical (ATC) Classification System, specifically ATC Code N (neurotransmitters). Specific sections are dedicated to the widely used electrodes based on the carbon materials, supporting electrolytes, and on electrochemical detection paradigms for neurological drugs and neurotransmitters within the groups referred to as ATC codes N01 to N07. We finally discuss emerging trends and future challenges such as the development of strategies for simultaneous detection of multiple targets with high spatial and temporal resolutions, the integration of microfluidic strategies for selective and localized analyte pre-concentration, the real-time monitoring of neurotransmitter secretions from active cell cultures under electro- and chemotactic cues, aptamer-based biosensors, and the miniaturization of the sensing system for detection in small sample volumes and for enabling cost savings due to manufacturing scale-up. The Electronic Supporting Material (ESM) includes review articles dealing with the review topic in last 40 years, as well as key properties of the analytes, viz., pKa values, half-life of drugs and their electrochemical mechanisms. The ESM also defines analytical figures of merit of the drugs and neurotransmitters. The article contains 198 references in the main manuscript and 207 references in the Electronic Supporting Material. Figureᅟ

No MeSH data available.


Related in: MedlinePlus