Cytochrome P450 2B6 Amperometric Biosensor for Continuous Monitoring of Propofol

Despite the growing evidence of improved patient outcomes and of a substantially reduced environmental impact of propofol-based total intravenous anesthesia when compared to volatile-based techniques, the vast majority of general anesthetics still use volatile agents for the maintenance phase. A significant reason for this is the lack of suitable point-of-care, real-time blood propofol measurement techniques. Here we present an enzyme-based electrochemical biosensor for the detection of propofol. Deactivated yeast cells expressing the enzyme cytochrome P450 2B6 are immobilized, alongside gold nanoparticles, within a chitosan film upon the surface of a screen printed electrode. In the presence of the cofactor NADPH, the enzyme converts propofol to a quinone/quinol redox pair that can be detected using simple electrochemistry. This approach avoids the issue of electrode fouling that commonly renders electrochemical propofol sensors impractical. The sensor has a limit of detection of 67 ± 7 ng/ml and a sensitivity of 4.2 ± 0.2 nA/
$\mu \text{g}$
/ml/mm
$^{\mathbf {2}}$
. It has been successfully demonstrated in a serum-like solution and has shown a linear response across the therapeutic range of propofol (1 –
$10~\mu \text{g}$
/ml). Additionally, the sensor has shown good specificity with regards to potential interfering compounds.