Newly found K-Thioflavin T competitive binding to DNA G-quadruplexes and the development of a label-free fluorescent biosensor with extra low detection limit for K determination in urine samples.

The determination of potassium ion K in body fluids is important in health monitoring and diagnoses. One of the interesting and simple methods for K detection is the use of label-free biosensors based on DNA G-quadruplexes (GQs) coupled with a specific fluorescent probe, such as Thioflavin T (ThT), which lights up when bound with K-stabilized GQs. However, these biosensors are not generally sensitive.