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.


(α) Design of an ATP detection system with FAD displaced signaling via AdS-SWV. (i) FAD as a suboptimal target is bound to the ATP aptamer (ATPA) preconjugated to streptavidin-coated magnetic beads (sphere). (ii) The presence of ATP, which is the native target for ATPA, displaces the prebound FAD (iii). The displaced electroactive FAD (iv) is measured via AdS-SWV [employing a graphene − AuNP − CPE (v)] to generate a measurable signal [23]. (β) Varying the aptamer concentration in the hybridization assay [23]. (γ) Method for calculation of the kinetic (kon and koff) and affinity (Kd) parameters for the hybridization assay
© Copyright Policy - OpenAccess
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4281370&req=5

Fig11: (α) Design of an ATP detection system with FAD displaced signaling via AdS-SWV. (i) FAD as a suboptimal target is bound to the ATP aptamer (ATPA) preconjugated to streptavidin-coated magnetic beads (sphere). (ii) The presence of ATP, which is the native target for ATPA, displaces the prebound FAD (iii). The displaced electroactive FAD (iv) is measured via AdS-SWV [employing a graphene − AuNP − CPE (v)] to generate a measurable signal [23]. (β) Varying the aptamer concentration in the hybridization assay [23]. (γ) Method for calculation of the kinetic (kon and koff) and affinity (Kd) parameters for the hybridization assay

Mentions: The competitive assay feature of aptamers was recently applied for calculating the (kon and koff) rates of the ATP aptamer to ATP using an electrochemical detection platform [23]. In this article, competitive binding of ATP to FAD pre-conjugated aptamer was applied to release FAD for subsequent detection at graphene-modified electrodes (Fig. 11α). A key aspect of this strategy is the application of a so-called “double-surface” technique-a nano-colloid of high surface area immobilized with the capture probe for target recognition and a separate graphene-modified surface for electrochemical detection. On one hand, the ensuing free 3D diffusion conditions and high capture probe concentration at the recognition surface ensure fast target binding kinetics, while on the other hand, the signaling electrode and transduction technique can be separately optimized, through surface modification, microfluidic pre-concentration and/or nanostructuring to enhance detection sensitivity. The concentration of the capture probe can be increased without limitations in terms of steric hindrance from neighboring hybridized capture probes and due to the inherently faster DNA hybridization in solution versus that on the signaling surface (see Fig. 11β). This resulted in a dynamic range that is five log orders wide a rapid hybridization kinetics even at the detection limit and thus were able to determine kinetic (kon and koff) and affinity (Kd) parameters of the assay. Hypothetical Fig. 11γ shows how this real-time monitoring capability can be applied to compute the kinetics (kon and koff) and affinity (Kd) parameters of the assay. The authors also challenged their assay on real samples, viz. blood serum, litchi fruit and banana samples.Fig. 11


Nanomaterial-based electrochemical sensing of neurological drugs and neurotransmitters.

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

(α) Design of an ATP detection system with FAD displaced signaling via AdS-SWV. (i) FAD as a suboptimal target is bound to the ATP aptamer (ATPA) preconjugated to streptavidin-coated magnetic beads (sphere). (ii) The presence of ATP, which is the native target for ATPA, displaces the prebound FAD (iii). The displaced electroactive FAD (iv) is measured via AdS-SWV [employing a graphene − AuNP − CPE (v)] to generate a measurable signal [23]. (β) Varying the aptamer concentration in the hybridization assay [23]. (γ) Method for calculation of the kinetic (kon and koff) and affinity (Kd) parameters for the hybridization assay
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig11: (α) Design of an ATP detection system with FAD displaced signaling via AdS-SWV. (i) FAD as a suboptimal target is bound to the ATP aptamer (ATPA) preconjugated to streptavidin-coated magnetic beads (sphere). (ii) The presence of ATP, which is the native target for ATPA, displaces the prebound FAD (iii). The displaced electroactive FAD (iv) is measured via AdS-SWV [employing a graphene − AuNP − CPE (v)] to generate a measurable signal [23]. (β) Varying the aptamer concentration in the hybridization assay [23]. (γ) Method for calculation of the kinetic (kon and koff) and affinity (Kd) parameters for the hybridization assay
Mentions: The competitive assay feature of aptamers was recently applied for calculating the (kon and koff) rates of the ATP aptamer to ATP using an electrochemical detection platform [23]. In this article, competitive binding of ATP to FAD pre-conjugated aptamer was applied to release FAD for subsequent detection at graphene-modified electrodes (Fig. 11α). A key aspect of this strategy is the application of a so-called “double-surface” technique-a nano-colloid of high surface area immobilized with the capture probe for target recognition and a separate graphene-modified surface for electrochemical detection. On one hand, the ensuing free 3D diffusion conditions and high capture probe concentration at the recognition surface ensure fast target binding kinetics, while on the other hand, the signaling electrode and transduction technique can be separately optimized, through surface modification, microfluidic pre-concentration and/or nanostructuring to enhance detection sensitivity. The concentration of the capture probe can be increased without limitations in terms of steric hindrance from neighboring hybridized capture probes and due to the inherently faster DNA hybridization in solution versus that on the signaling surface (see Fig. 11β). This resulted in a dynamic range that is five log orders wide a rapid hybridization kinetics even at the detection limit and thus were able to determine kinetic (kon and koff) and affinity (Kd) parameters of the assay. Hypothetical Fig. 11γ shows how this real-time monitoring capability can be applied to compute the kinetics (kon and koff) and affinity (Kd) parameters of the assay. The authors also challenged their assay on real samples, viz. blood serum, litchi fruit and banana samples.Fig. 11

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.