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)