Metal oxide decorated carbon nanocomposite electrodes for propofol monitoring

Despite the growing evidence of the benefits of total-intravenous anaesthesia using propofol compared to conventional volatile-based anaesthesia, both in terms of environmental impact and patient outcomes, the majority of administered general anaesthetics use volatile agents. A significant reason for this is the lack of suitable methods for continuous, real-time propofol monitoring. Here we present a cytochrome P450 2B6/carbon nanotube/graphene oxide/metal oxide nanocomposite sensor for propofol monitoring. The enzyme prevents electrode fouling by converting the propofol into a quinone/quinol redox pair and the nanocomposite enables rapid and sensitive detection. The nanocomposite was synthesised via a simple ‘green synthesis’-based approach using an extract of common bay laurel. It was found that composites containing iron oxide nanoparticles resulted in the best performance, with a limit of detection of 7.0 ± 0.7 ng/ml and a sensitivity of 29.9 ± 6.4 nA/μg/ml/mm2. The sensor demonstrated good specificity with respect to several common perioperative drugs, propofol detection was demonstrated in a ‘serum-like’ solution and produced a linear response across the therapeutic range of propofol (1–10 μg/ml). •Functionalisation of electrode with enzyme cytochrome P450 2B6 avoids electrode fouling during propofol detection.•Functionalisation of electrode with carbon metal oxide nanocomposite significantly increases sensitivity.•Nanocomposites incorporating iron oxide nanoparticles achieve best performance.•Sensor demonstrates good selectivity towards several perioperative drugs.