Development of a DNA biosensor for the detection of phenylketonuria based on a screen-printed gold electrode and hematoxylin

Abstract

Phenylketonuria (PKU), which is a deficiency of an important metabolic enzyme, is caused by several identified point mutations in populations around the world. Several methods have been developed for the detection of DNA mutations so far, including biosensors, especially electrochemical biosensors. In this research, we developed a novel biosensor using a special electrochemical label, hematoxylin. A screen-printed gold electrode (SPGE) modified with thiolated detection probes was used to detect the point mutation IVS10nt-11g→a of phenylalanine hydroxylase (PAH) enzyme. The methodology and its efficiency have been proved using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies in [Fe(CN)₆]^3−/4− solution. Under optimized conditions, the biosensor was able to detect the target DNA ranging from 20 pM to 150 nM with a detection limit of 8.5 pM. In addition, the selectivity of the biosensor was tested by the application of single-base mismatched and three-base mismatched oligonucleotides in comparison to the target DNA. Finally, the interference studies were performed in order to confirm the functionality of the biosensor in real sample applications, which proved good functionality for the biosensor in simulated extracted DNA solutions.