Improved reuse and storage performances at room temperature of a new environmentally friendly lactate oxidase biosensor prepared by ambient electrospray immobilization

A new, environmentally friendly lactate oxidase (LOX) based biosensor for lactate detection, with unprecedented reuse and storage capabilities at room temperature, has been manufactured using the ambient electrospray deposition (ESD) technique. This technology allows for an efficient, green and easy ambient soft-landing immobilization of the LOX enzyme on a cheap commercial screen-printed Prussian blue/carbon electrode (PB/C-SPE), employing sustainable chemistry. This study shows how ESD can confer the biosensor the ability to be stored at ambient pressure and temperature for long periods without compromising the enzymatic activity. The fabricated biosensor shows a storage capability for up to 90 days, without any particular care under storage conditions, and a reuse performance for up to 24 measurements on both the electrode just prepared and on a three-months-old electrode. The LOX-based biosensor has been tested for lactate detection in the linear range of 0.1-1 mM with a limit of detection of 0.07 ± 0.02 mM and does not show any memory effects. The absence of an entrapment matrix as well as any additional hazardous chemicals during the immobilization phase makes the process competitive in terms of environmental sustainability and toxicity. Moreover, the application of a new electrospray deposition cycle on the used biosensors makes the biosensors work again with performances comparable to those of freshly made ones. This demonstrates that the technique is excellent for recycling and eliminates the waste of disposable devices.