Highly sensitive and stable sensor for the detection of capsaicin using electrocatalytic carbon dots grafted onto indium tin oxide

• Carbon dots (CDs) were synthesized from iota-carrageenan. • CDs were grafted onto an ITO substrate via thermal annealing. • CD-grafted ITO substrate was used for capsaicin detection. • It could sense capsaicin with a wide linear range 0.05−500 μM and a low LOD of 5.4 nM. • The sensor demonstrated good selectivity and recyclability towards capsaicin. In this work, a highly sensitive and stable capsaicin sensor was developed from carbon dots synthesized from iota-carrageenan. The carbon dots were grafted onto an indium tin oxide (ITO) substrate via a novel one-step thermal annealing process. This was used as an electrode for the electrochemical detection of capsaicin. The carbon dot-grafted ITO electrode was sensitive across a wide linear range from 0.05 to 500 μM, with a remarkably low detection limit of 5.4 nM. The electrode showed excellent recyclability over 450 cycles, suggesting that it was electrochemically stable and can be reused for several hundred times. It demonstrated good selectivity towards capsaicin in the presence of multiple interferences: d -(+)-glucose, citric acid, l -ascorbic acid, Na + , K + , Mg 2+ , Ca 2+ , Fe 2+ , and Cl − . A recovery test was performed using Cayenne pepper, Tabasco sauce, and Thai chili, yielding the recovery in the range 92–108 %. In addition to high sensitivity, stability, and selectivity, the sensor could produce the detection results within 5 min. The novel capsaicin sensor developed here has potential uses for quality control in the agricultural, food, and pharmaceutical sectors.