Electrochemical biosensor based on NAD(P)H-dependent quinone reductase for rapid and efficient detection of vitamin K.

Vitamin K refers to a group of vitamins that play an important role in blood coagulation and regulation of bone and vascular metabolism. However, vitamin K may give severe side effects in animal and humans when improperly added to food and feed due to its toxicity. Here, an electrochemical biosensor, based on the YaiB NADPH-dependent quinone reductase from Lactococcus lactis (YaiB), was developed to achieve rapid and redox probe-free detection of vitamin K. First, the ability of the carbon electrode to distinguish between 1,4-benzoquinone and hydroquinone was demonstrated. Then, we engineered YaiB to work as a bioreceptor immobilized at the electrode and its sensitivity and specificity to reduce vitamin K were demonstrated. Finally, to demonstrate the practical potential of the biosensor, we tested it directly in spiked milk samples, achieving 15-minute quantification of the vitamin K. The limit of detection was 0.87 µM and 4.1 µM in buffer and milk, respectively.