Adsorption

Engineering

Biology

Electrochemistry

Materials science

Chromatography

Tungsten

Tungsten disulfide

Nanocomposite

Aptamer

Inorganic chemistry

Chemical engineering

Physical chemistry

Genetics

Combinatorial chemistry

Cationic polymerization

Nanotechnology

Organic chemistry

Carbon quantum dots

Linear range

Chemistry

Electrode

Detection limit

Quantum dot

Electrochimica Acta

In this paper, a novel electroactive material named as carbon quantum dots-tungsten disulfide nanocomposite (CQDs-WS2) was prepared via a facile self-assembly method. Based on CQDs-WS2 modified glassy carbon electrode (CQDs-WS2/GCE), a label-free electrochemical aptasensing strategy was proposed to sensitively determine sulfamethazine (SMZ). Cationic polyethyleneimine (PEI) were employed to form complexes with negatively charged SMZ-binding aptamers immobilized on CQDs-WS2/GCE by amidation reaction, which decreased the adsorption capacity of [Ru(NH3)6]3+ to aptamers. When SMZ existed, the change of aptamer conformation due to the formation of SMZ/aptamer complex would lead to decrease in adsorption amount of PEI. More adsorbed [Ru(NH3)6]3+ on aptamer can produce enhanced reduction current. On the basis of CQDs-WS2 as electroactive materials, aptamer as a recognition receptor, PEI as electrostatic adsorbent of aptamer, and [Ru(NH3)6]3+ as an electroactive indicator, a signal-on electrochemical aptasensor was constructed for detection of SMZ with high sensitivity. The SMZ aptasensor displayed wide linear response in the 10 pM to 1.0 µM concentration range and a low detection limit of 4.0 pM. The method can be applied to quantitation analysis of antibiotic residue in food and environmental samples.

Signal-on electrochemical aptasensor for sensitive detection of sulfamethazine based on carbon quantum dots/tungsten disulfide nanocomposites