Label-Free Electrochemical Aptasensor Based on MXene-Gold Nanocomposite Modified Glassy Carbon Electrode for Sensitive Detection of Tryptophan in Food

Integrating nanomaterials with aptasensors has emerged as a promising strategy to enhance the performance of electrochemical sensing platforms. In this study, synthesized gold nano cauliflowers (Au NCFs) were deposited on MXene nanosheets to construct an Au NCFs/MXene composite, leveraging their high electrical conductivity. Then, a glassy carbon electrode (GCE) modified with the Au NCFs/MXene composite was used to construct a label-free impedimetric aptasensor. The combination of MXene and Au NCFs not only improves the electrochemical behavior of the system, but also enhances aptamer immobilization through strong Au-S bonding with thiol-modified aptamer strands. The resulting electrochemical aptasensor provided a robust platform for the ultrasensitive quantification of tryptophan (Trp). The aptasensor showed high sensitivity, with a wide linear range from 0.10 fM to 300 nM and a low detection limit of 0.03 fM. It was also successfully applied for the electrochemical determination of Trp in food samples, proving its practicality for real applications.