Polythymine Oligonucleotide‐Modified Gold Electrode for Voltammetric Determination of Mercury(II) in Aqueous Solution

Polythymine oligonucleotide (PTO)‐modified gold electrode (PTO/Au) was developed for selective and sensitive Hg²⁺ detection in aqueous solutions. This modified electrode was prepared by self‐assembly of thiolated polythymine oligonucleotide (5′‐SH‐T₁₅‐3′) on the gold electrode via Au? S bonds, and then the surface was passivated with 1‐mercaptohexanol solution. The proposed electrode utilizes the specific binding interactions between Hg²⁺ and thymine to selectively capture Hg²⁺, thereby reducing the interference from coexistent ions. After exchanging the medium, electrochemical reduction at ?0.2 V for 60 s, voltammetric determination was performed by differential pulse voltammetry using 10 mM HEPES; pH 7.2, 1 M NaClO₄ as supporting electrolyte. This electrode showed increasing voltammetric response in the range of 0.21 nM Hg²⁺, with a relative standard deviation of 5.32% and a practical detection limit of 60 pM. Compared with the conventional stripping approach, the modified electrode exhibits good sensitivity and selectivity, and is expected to be a new type of green electrode.