A novel aptasensor for malathion blood samples detection based on DNA–silver nanocluster

Abstract

Pesticides have drawn great attention because of their bad effects on health and the environment. Among these, organophosphates were the most widely used in China and malathion is the most common. Direct or indirect contact with malathion does harm to our nervous, respiratory and digestive systems. Thus, accurate detection of malathion in biological samples is very useful to ensure the safety of human health, especially in agricultural countries. In this paper, a sensitive and selective aptasensor based on DNA–silver nanocluster probes has been proposed for the simple and efficient detection of malathion in biological samples. First its feasibility was verified when the UV-vis absorbance apparently decreased with inclusion of malathion and the response differed from that with other chemicals. Then under optimized conditions, a concurrent decrease in absorbance with the addition of malathion from 0 μg mL⁻¹ to 25 μg mL⁻¹ was achieved with a limit of detection of 25 pg mL⁻¹. The linear equations between the UV-vis absorbance spectrum and the concentration of malathion were y = 10.167x + 1.051, R² = 0.986 (range from 0.000025 μg mL⁻¹ to 0.025 μg mL⁻¹) and y = 0.0136x + 1.431, R² = 0.995 (range from 0.25 μg mL⁻¹ to 25 μg mL⁻¹). Moreover, investigations in blood samples were conducted to test the biocompatibility of the aptasensors for the sake of practical applications in forensic research. The detection results of the proposed method were almost consistent with those of conventional high-performance liquid chromatography (HPLC). In view of its simplicity, low cost, selectivity, sensitivity and reliability, the aptasensor introduced in our work may potentially be a better way to detect malathion in forensic toxicology examination.