Electrochemical Aptamer-Based Sensors: A Platform Approach to High-Frequency Molecular Monitoring In Situ in the Living Body

Dauphin‐Ducharme, Philippe; Ploense, Kyle L.; Arroyo‐Currás, Netzahualcóyotl; Kippin, Tod E.

doi:10.1007/978-1-0716-1803-5_25

Cited by 14 publications

(10 citation statements)

References 21 publications

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“…To adapt the phenylalanine-detecting sensor to placement in the living body, we fabricated indwelling sensors using 75 μm diameter by 3 mm long gold wire electrodes. We matched these with equal-diameter platinum counter and chloride-anodized silver reference electrodes (Figure C, left) and encased the bundle in a 22-gauge catheter in which slots were cut to provide blood access . The resulting devices are small enough to be inserted into the jugular veins of anesthetized Sprague-Dawley rats (Figure C, right).…”

Section: Resultsmentioning

confidence: 99%

“…We matched these with equal-diameter platinum counter and chlorideanodized silver reference electrodes (Figure 1C, left) and encased the bundle in a 22-gauge catheter in which slots were cut to provide blood access. 33 The resulting devices are small enough to be inserted into the jugular veins of anesthetized Sprague-Dawley rats (Figure 1C, right). Because rats have four jugular veins (left and right interior and exterior pairs), such placements cause only minor changes to blood flow and likely no changes to molecular physiology.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Seconds-Resolved, In Situ Measurements of Plasma Phenylalanine Disposition Kinetics in Living Rats

2021

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Current knowledge of the disposition kinetics of endogenous metabolites is founded almost entirely on poorly time-resolved experiments in which samples are removed from the body for later, benchtop analysis. Here, in contrast, we describe real-time, seconds-resolved measurements of plasma phenylalanine collected in situ in the body via electrochemical aptamer-based (EAB) sensors, a platform technology that is independent of the reactivity of its targets and thus is generalizable to many. Specifically, using indwelling EAB sensors, we have monitored plasma phenylalanine in live rats with a few micromolar precision and a 12 s temporal resolution, identifying a large-amplitude, few-seconds phase in the animals’ metabolic response that had not previously been reported. Using the hundreds of individual measurements that the approach provides from each animal, we also identify inter-subject variability, including statistically significant differences associated with the feeding status. These results highlight the power of in vivo EAB measurements, an advancement that could dramatically impact our understanding of physiology and provide a valuable new tool for the monitoring and treatment of metabolic disorders.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Seconds-Resolved, In Situ Measurements of Plasma Phenylalanine Disposition Kinetics in Living Rats

2021

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“…E-AB sensors are composed of a redox-reporter-modified short nucleic acid sequence (an aptamer) immobilized on a gold electrode surface that specifically binds to a target molecule (Figure ). − Upon target recognition, the redox reporter undergoes a binding-induced change in electron transfer that is kinetically limited by its diffusion to the electrode − and/or an intrinsic change in its electron transfer (i.e., reorganizational energy), allowing for fast (i.e., subsecond) quantitative determination of the target concentration directly in complex matrices and in the body. − Using aptamers for different ligands, E-AB sensors can measure a wide variety of targets (i.e., antibiotics, chemotherapeutics, drugs of abuse, proteins, etc. ), highlighting their generalizability. − As E-AB sensors rely on an electrochemical signaling mechanism, they can be miniaturized and powered by a handheld portable device, leaving them ideally suited to transform our understanding of drug pharmacology and design precision medicine approaches for use at the patient’s bedside.…”

Section: Introductionmentioning

confidence: 99%

Finding the Lost Dissociation Constant of Electrochemical Aptamer-Based Biosensors

et al. 2023

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Electrochemical aptamer-based (E-AB) biosensors afford real-time measurements of the concentrations of molecules directly in complex matrices and in the body, offering alternative strategies to develop innovative personalized medicine tools. While different electroanalytical techniques have been used to interrogate E-AB sensors (i.e., cyclic voltammetry, electrochemical impedance spectroscopy, and chronoamperometry) to resolve the change in electron transfer of the aptamer’s covalently attached redox reporter, square-wave voltammetry remains a widely used technique due to its ability to maximize the redox reporter’s faradic contribution to the measured current. Several E-AB sensors interrogated with this technique, however, show lower aptamer affinity (i.e., μM–mM) even in the face of employing aptamers that have high affinities (i.e., nM−μM) when characterized using solution techniques such as isothermal titration calorimetry (ITC) or fluorescence spectroscopy. Given past reports showing that E-AB sensor’s response is dependent on square-wave interrogation parameters (i.e., frequency and amplitude), we hypothesized that the difference in dissociation constants measured with solution techniques stemmed from the electrochemical interrogation technique itself. In response, we decided to compare six dissociation constants of aptamers when characterized in solution with ITC and when interrogated on electrodes with electrochemical impedance spectroscopy, a technique able to, in contrast to square-wave voltammetry, deconvolute and quantify E-AB sensors’ contributions to the measured current. In doing so, we found that we were able to measure dissociation constants that were either separated by 2–3-fold or within experimental errors. These results are in contrast with square-wave voltammetry-measured dissociation constants that are at the most separated by 2–3 orders of magnitude from ones measured by ITC. We thus envision that the versatility and time scales covered by electrochemical impedance spectroscopy offer the highest sensitivity to measure target binding in electrochemical biosensors relying on changes in electron-transfer rates.

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“…We then insulated the gold wire working electrode with polytetrafluoroethylene, bundled it with similar-dimension chloride-anodized silver wire reference and platinum wire counter electrodes, and placed the three into a 22-gauge catheter for later intravenous insertion . When interrogated with a square wave frequency of 80 Hz, the signaling current of the resulting sensor increases upon target binding (Figure A, red curve).…”

Section: Resultsmentioning

confidence: 99%

Real-Time, Seconds-Resolved Measurements of Plasma Methotrexate In Situ in the Living Body

et al. 2022

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Dose-limiting toxicity and significant patient-to-patient pharmacokinetic variability often render it difficult to achieve the safe and effective dosing of drugs. This is further compounded by the slow, cumbersome nature of the analytical methods used to monitor patient-specific pharmacokinetics, which inevitably rely on blood draws followed by post-facto laboratory analysis. Motivated by the pressing need for improved “therapeutic drug monitoring”, we are developing electrochemical aptamer-based (EAB) sensors, a minimally invasive biosensor architecture that can provide real-time, seconds-resolved measurements of drug levels in situ in the living body. A key advantage of EAB sensors is that they are generalizable to the detection of a wide range of therapeutic agents because they are independent of the chemical or enzymatic reactivity of their targets. Three of the four therapeutic drug classes that have, to date, been shown measurable using in vivo EAB sensors, however, bind to nucleic acids as part of their mode of action, leaving open questions regarding the extent to which the approach can be generalized to therapeutics that do not. Here, we demonstrate real-time, in vivo measurements of plasma methotrexate, an antimetabolite (a mode of action not reliant on DNA binding) chemotherapeutic, following human-relevant dosing in a live rat animal model. By providing hundreds of drug concentration values, the resulting seconds-resolved measurements succeed in defining key pharmacokinetic parameters, including the drug’s elimination rate, peak plasma concentration, and exposure (area under the curve), with unprecedented 5 to 10% precision. With this level of precision, we easily identify significant (>2-fold) differences in drug exposure occurring between even healthy rats given the same mass-adjusted methotrexate dose. By providing a real-time, seconds-resolved window into methotrexate pharmacokinetics, such measurements can be used to precisely “individualize” the dosing of this significantly toxic yet vitally important chemotherapeutic.

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Electrochemical Aptamer-Based Sensors: A Platform Approach to High-Frequency Molecular Monitoring In Situ in the Living Body

Cited by 14 publications

References 21 publications

Seconds-Resolved, In Situ Measurements of Plasma Phenylalanine Disposition Kinetics in Living Rats

Seconds-Resolved, In Situ Measurements of Plasma Phenylalanine Disposition Kinetics in Living Rats

Finding the Lost Dissociation Constant of Electrochemical Aptamer-Based Biosensors

Real-Time, Seconds-Resolved Measurements of Plasma Methotrexate In Situ in the Living Body

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