Liquid exfoliated graphene@Ti₃C₂ MXene based dual-signal aptasensing interface for Cd²⁺ and Pb²⁺ simultaneous detection in water and vegetables

As ubiquitous pollutants, heavy metal ions can accumulate in the food chain, increasing toxicity through synergistic effects and posing health risks to humans and other organisms. In this study, we successfully developed a dual-signal aptasensing interface for simultaneous detection of cadmium ions (Cd²⁺) and lead ions (Pb²⁺). The 2D layered Ti₃C₂ MXene and liquid exfoliated graphene (LEG) composite nanomaterials were employed as ITO electrode modification materials, which exhibited enhanced electrochemical properties. The Cd²⁺-specific aptamer labeled with Nile blue and Pb²⁺-specific aptamer labeled with ferrocene bind to their complementary strands immobilized on the electrode surface, resulting in a dual-signal interface. In the presence of target ions, the aptamers specifically recognized and captured the targets, subsequently detaching from the electrode surface, leading to changes in the dual-signals and thereby enabling simultaneous detection of Cd²⁺ and Pb²⁺. The limits of detection for Cd²⁺ and Pb²⁺ were determined to be 0.689 pM and 1.548 pM, with linear response ranges of 0.1 pM to 10 μM and 0.01 pM to 10 μM. The effectiveness of the proposed aptasensor in determining Cd²⁺ and Pb²⁺ simultaneously in water and vegetables has been demonstrated, providing substantial evidence for its potential application in food safety and environmental monitoring.