A simple strategy for low-cost portable monitoring of plasma drug concentrations using a sustainable boron-doped-diamond chip

Abstract

Monitoring of plasma drug concentrations is required for effective and safe pharmacotherapies. Recent technical advances gave rise to various portable or wearable biosensors for rapid on-site monitoring. These devices are not yet popular owing to not only insufficient evaluation of accuracy on clinical samples and sensor-to-sensor variability but also the need for complicated costly fabrication processes. To address these bottlenecks, here, we describe a simple strategy based on boron-doped diamond (BDD) without any engineering modifications. As a test compound, we selected pazopanib, a molecular-targeting anticancer drug whose monitoring is recommended. When assaying rat plasma spiked with pazopanib, a sensing system constructed from a ~1 cm2 BDD plate chip detected concentrations in the clinically relevant range. The response was stable in a series of 60 measurements on the same chip, indicating excellent repeatability of the assay and high sustainability of the material. When plasma samples collected from orally treated healthy rats or patients with cancers were analysed with the system, the results overall matched the concentrations determined by liquid chromatography with mass spectrometry. Additionally, the reproducibility of BDD chip–based assays was tested. Finally, we constructed a portable system with a palm-sized sensor containing a BDD chip and demonstrated that the setup successfully quantifies the drug in plasma from ~40 µL of whole blood of a dosed rat within a short turnaround time: ~10 min. This approach with the ‘reusable’ sensor, which can also possibly detect other drug types, may accelerate point-of-testing assays and advance personalised medicine while reducing medical costs.