Synthesis and characterization of a bifunctional nanoprobe for CGG trinucleotide repeat detection

Abstract

A novel bifunctional nanoprobe was designed and used in an electrochemical sensor to rapidly detect CGG trinucleotide repeats. The bifunctional nanoprobe was synthesized using carboxyl-functionalized Fe₃O₄ magnetic nanoparticles as carriers of nucleic acids recognition molecule and electron mediator-ferrocene derivatives. Both the small molecules with the terminal amino group were immobilized on the surface of the magnetic nanoparticles via an amide bond, which resulted in double functions of recognition and electrochemical activity. An electrochemical sensor based on the new bifunctional nanoprobe was established for CGG trinucleotide repeat detection. After the target DNA was captured by the sensor, the recognition molecule on the surface of the bifunctional nanoprobe could interact with the G base of the CGG trinucleotide repeat selectively. This allowed the bifunctional nanoprobes to be enriched on the modified electrode surface, which resulted in a remarkable electrochemical signal. CGG trinucleotide repeat can be easily discriminated from other trinucleotide repeats by the sensor. Furthermore, these results demonstrated that the new sensor exhibited an excellent selectivity to the Fragile X syndrome disease biomarker CGG repeat DNA. The proposed method is simple and rapid, the target DNA is label-free and has excellent repeatability for the detection of the CGG trinucleotide repeat because of the double function of the designed nanoprobe. This sensing strategy will provide great promise for the early diagnosis of neurodegenerative diseases associated with trinucleotide repeats.