Monitoring circulating drug levels is critical for pharmacotherapy as it can be leveraged to personalize dosing, evaluate adherence, and prevent abuse. However, in the current clinical practice, it involves invasive blood draws (esp., for dosing) and high-cost lab analyses. Bypassing these limitations, we present a non-invasive and accessible drug monitoring modality that allows for capturing the drug level with one-touch and in a sample-to-answer manner. In our approach, we leveraged the fact that many circulating drug molecules partition onto the fingertip surface at a relatively high flux (primarily via natural perspiration) and in correlation to their circulating levels.<br/> <br/>Accordingly, we developed a thin hydrogel (TH)-coated electrochemical sensor, wherein the hydrogel layer serves as an intermediary medium for the epidermal collection/electrochemical sensing of the partitioned molecules. We adapted the underlying electrochemical sensing interface to target acetaminophen (APAP) as a model drug, given that its supratherapeutic administration is one of the leading causes of liver failure. In that regard, we utilized a Nafion-coated boron-doped diamond electrode and our previously reported surface engineering methodology for interference-free voltammetric sensing. To guide the TH-sensor development and translate the touch-based readouts into physiologically meaningful measurements, we devised a dedicated signal interpretation framework (validated via finite element simulation). This framework models the unique analyte mass transport behavior at hand, which involves the continuous epidermal influx of analytes into the hydrogel. The modelling results indicated that thinning down the hydrogel allows for shortening the response time and amplifying the signal (critical for measuring drugs that circulate at low levels). Thus, in our TH-sensor fabrication procedure, we introduced a rehydration step to reduce the hydrogel thickness down to 220 μm. By conducting human subject studies, we validated our presented solution. One-touch measurements were performed before and at intermittent time points after the APAP intake to construct the drug’s pharmacokinetic profile (cross-validated against salivary drug measurements, per standard protocol). The results indicate that the touch-based measurements can detect the presence of an equivalent circulating APAP level of ~40 μM in 30 s, demonstrating the potential clinical utility of the devised drug monitoring modality.

Thin hydrogel-mediated electrochemical sensing for one-touch drug monitoring

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.