Detection of femtomolar level osteosarcoma-related gene via a chronocoulometric DNA biosensor based on nanostructure gold electrode

Abstract

Guangxian Zhong1,3,7,*, Ailin Liu1,2,*, Xiongwei Xu4, Zhouliang Sun5, Jinyuan Chen1,2, Kun Wang1,5, Qicai Liu6, Xinhua Lin1,2, Jianhua Lin3,71Department of Pharmaceutical Analysis, Faculty of Pharmacy, Fujian Medical University, Fuzhou, 2Nano Biomedical Technology Research Center, Fujian Medical University, Fuzhou, 3Department of Orthopedics, 4Department of Pharmacy, the First Affiliated Hospital of Fujian Medical University, Fuzhou, 5Department of Pharmacy, the First Affiliated Hospital of Xiamen University, Xiamen, 6Department of Clinical Laboratory, the First Affiliated Hospital of Fujian Medical University, Fuzhou, 7Fujian Institute of Orthopedics, the First Affiliated Hospital of Fujian Medical University, Fuzhou, People's Republic of China*These authors contributed equally to this studyAbstract: In this paper, a sensitive chronocoulometric deoxyribonucleic acid (DNA) biosensor based on a nanostructure gold electrode was fabricated for detection of the femtomolar level survivin gene which was correlated with osteosarcoma by using hexaamine-ruthenium III complexes, [Ru(NH3)6]3+, as the electrochemical indicator. The effect of different frequencies on the real surface area of the nanostructure gold electrode obtained by repetitive square-wave oxidation reduction cycle was investigated. At the optimal frequency of 8000 Hz, the real surface of the developed nanostructure gold electrode was about 42.5 times compared with that of the bare planar gold electrode. The capture probe DNA was immobilized on the nanostructure gold electrode and hybridized with target DNA. Electrochemical signals of hexaamine-ruthenium III bound to the anionic phosphate of DNA strands via electrostatic interactions were measured by chronocoulometry before and after hybridization. The increase of the charges of hexaamine-ruthenium III was observed upon hybridization of the probe with target DNA. Results indicate that this DNA biosensor could detect the femtomole (fM) concentration of the DNA target quantitatively in the range of 50 fM to 250 fM; the detection limit of this DNA biosensor was 5.6 fM (signal to noise = 3). This new biosensor exhibits excellent sensitivity and selectivity and has been used for an assay of polymerase chain reaction (PCR) with a satisfactory result.Keywords: chronocoulometric DNA biosensor, survivin gene, hexaamine-ruthenium III complexes, nanostructure gold electrode, femtomolar level