Efficient electrochemical biosensors for ethynylestradiol based on the laccase enzyme supported on single walled carbon nanotubes decorated with nanocrystalline carbon quantum dots

A new hybrid nanomaterial based on single-walled carbon nanotubes incorporating nanocrystalline carbon quantum dots (SWCNT/C-dots) was developed and characterized by means of high resolution transmission electron microscopy, atomic force microscopy, Raman spectroscopy and electrochemical techniques. A glassy carbon electrode modified with SWCNT/C-dots exhibited an enhanced electrocatalytic response for 17 alpha-ethynylestradiol, reflecting an increase of the active area of the hybrid material, promoted by the C-dots. However, the best activity was observed for laccase immobilized on CGE/SWCNT/C-dots, suggesting that the nanocrystalline C-dots improve the electron transport between the substrate, SWCNTs and the copper ions in the enzyme active sites. Such an association provided a very efficient bioelectrochemical sensor for the 17 alpha-ethynylestradiol endocrine interfering agent, with a detection limit of 4.0 nmol L-1 in real samples.