Analytical Sciences

Sensitive and Selective Detection of Mercury Ions in Aqueous Media Using an Oligonucleotide-functionalized Nanosensor and SERS Chip

Qiang ZOU,*1,*2,*3 Xin LI,*1 Tao XUE,*4 Shentong MO,*2 Qi SU,*2 and Jia ZHENG*2

*1 Department of Marine Environmental Science and Technology, School of Marine Science and Technology, Tianjin University, Tianjin, 300072, China
*2 School of Microelectronics, Tianjin University, Tianjin, 300072, China
*3 Xuanhuai School of Innovation and Entrepreneurship, Tianjin University, Tianjin, 300072, China
*4 College of Material Science and Engineering, Tianjin University, Tianjin, 300072, China

A surface-enhanced Raman scattering (SERS) platform for the selective trace analysis of Hg²⁺ ions was reported, based on poly-thymine (T) aptamer/2-naphthalenethiol (2-NT)-modified gold nanoparticles (AuNPs), which was an oligonucleotide-functionalized nanosensor and SERS chip. 2-NT was used as a Raman reporter, and T aptamer could form a T-Hg²⁺-T structure with Hg²⁺ ions making an SERS nanosensor absorbed to the SERS chip. The optimum concentrations of DNA and 2-NT were obtained. An average of 960 DNA molecules attached to each AuNP were measured. The limit of detection (LOD) was 1.0 ppt (1.0 × 10⁻¹² g/mL), which is far below the limit of 10.0 ppb for drinking water, stipulated by the World Health Organization. The sensor has the advantages of low detection cost, a simple sample pretreatment, a green solution and reducing false positives. Furthermore, the nanosensor was used for the determination of trace Hg²⁺ in the water of a lake; a reliable result was obtained accurately.

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