Label-free electrochemical detection of neuraminidase activity: A facile whole blood diagnostic probe for infectious diseases

Neuraminidase has been found in many pathogenic bacteria and influenza viruses, and it plays important roles in the spreading of pathogens; thus, it is an important biomarker for infectious diseases. We developed a simple, rapid, sensitive, and label-free electrochemical assay to detect neuraminidase activity, by employing a newly synthesized latent probe AP-Neu5Ac that acts as a substrate for neuraminidase. The release of p-aminophenol, resulting from the neuraminidase-catalyzed hydrolysis of AP-Neu5Ac, was monitored using linear sweep voltammetry. Our assay was highly sensitive with a limit of detection of 5.6 ng mL⁻¹, which is comparable to those of other currently available sensitive methods such as ELISA and luminescence-based assays. The AP-Neu5Ac probe is a non-protein reagent, and was shown to be robust, highly stable at room temperature and durable. Analysis of whole blood samples containing neuraminidase revealed the reproducibility of our method in colored and cloudy samples. Our sensor of neuraminidase activity was shown to be superior to those used in previously reported methods The significance of these results showed the potential application of this method for monitoring biological status or progress in the recovery from infectious diseases caused by pathogenic neuraminidase-producing bacteria or influenza virus.