Study On Electrochemiluminescence Biosensor For Determination Of Mercury Ion In Agricultural Water

Divalent mercury ion(Hg²⁺)is a highly toxic heavy metal ion and can not be degraded by microorganisms in natural environment.Hg²⁺in water can remain in the soil or crops through irrigation.It will affect the normal growth of crops,causing crops withered and even die,and resulting in reduced yield and quality of crops,which leading to the loss of agricultural economy.Therefore,it is necessary to detect the content of Hg²⁺in agricultural water.It can provide a theoretical basis for water quality assessment and subsequent treatment,thereby reducing the agricultural economic losses caused by Hg²⁺.For the analysis of Hg²⁺,traditional detection methods have some limitations,such as expensive equipment,special operation of the operator and cumbersome preprocessing.Therefore,the development of a new convenient,sensitive,low-cost detection technology has become an inevitable trend.The main work of this paper is to develop the simple,sensitive and low-cost electrochemiluminescence?ECL?biosensor for the detection of Hg²⁺,which provides the theoretical basis for the study of portable detection devices directly used in agricultural production.The main contents of this paper can be divided into the following two parts:?1?First,carbon nitride quantum dots?g-C₃N₄ QDs?were prepared by solid-state reaction.Then,amino-modified DNA1 and DNA2 were combined with Ru?dcbpy?₃²⁺and g-C₃N₄ QDs via amide reaction,respectively.A novel ECL biosensor based on Ru?dcbpy?3²⁺and g-C₃N₄ QDs composites was constructed.When the Hg²⁺is added,DNA1 and DNA2 combine with each other by T-Hg²⁺-T interaction so that the distance between Ru?dcbpy?₃²⁺and g-C₃N₄ QDs becomes closer and ECL signal further increases.The ECL biosensor based on the above principle realizes the high sensitivity and selectivity for Hg²⁺analysis.Under the optimum experimental conditions,the linear range of the biosensor for Hg²⁺determination is from1.00×10^-14 mol·L^-1 to 1.00×10^-9 mol·L^-1,and the detection limit is 3.30×10^-15 mol·L^-1?S/N=3?.Successfully,the biosensor has been applied to the detection of Hg²⁺in the water of the Beijing-Hangzhou Grand Canal,which provides a new strategy for ECL sensing technology in the detection of Hg²⁺in agricultural water.?2?In order to shorten the distance of electron transfer between the luminophor and the co-reactant,reduce the loss of the reaction energy and improve the luminous efficiency,the luminophor Ru?bpy?₃²⁺and the co-reactant g-C₃N₄ QDs are combined by electrostatic interaction.Then it was encapsulated in silica nanoparticles?SiO₂?to form a self-enhanced ECL probe?Ru-QDs@SiO2?through the reverse microemulsion method.A simple and new self-enhanced ECL biosensor was constructed based on the self-enhanced ECL probe and T-rich DNA as the recognition element.The single-stranded DNA can be adsorbed on the surface of nanospheres,a barrier can be formed between the luminescent material and the electrode.When the target Hg²⁺is present,the single-stranded DNA forms rigid double-stranded structure,which cannot be adsorbed on the surface of the nanosphere,and the luminescent material can be directly in contact with the electrode,leading to the ECL signal enhanced.The analysis of Hg²⁺utilizing the ECL biosensor shows higher sensitivity,better selectivity and reproducibility.Under the optimum experimental conditions,the linear range is from 1.00×10^-10 mol·L^-1 to 1.00×10^-5mol·L^-1,and the detection limit is 3.30×10^-11 mol·L^-1?S/N=3?.Finally,the ECL biosensor was used to detect the concentration of Hg²⁺in water of the Beijing-Hangzhou Grand Canal.The recovery rate was between 97%and 106.2%,and the relative standard deviation was between1.84%and 5.4%.