“Superior snowflake” AuPd/Cu2S as substrate and satellite-like Au/CeO2 as signal probe to improve the sensitivity of electrochemical sensor for kanamycin detection

Abstract

Many novel assays have been realized for the detection of antibiotics in food and environment. Low sensitivity and poor stability limit their application in electrochemical biosensors. The snowflake-like AuPd/Cu₂S used in electrochemical sensor has a large area and high conductivity. Using it as an electrode modification material can effectively increase the working area of the electrode, thus further improving the current response. A more perfect snowflake-like Cu₂S structure were synthesized after optimized for the substrate. After calculation it was surprisingly found that the two most prominent structures in each branch shape were divided into two parts by using them as the dividing line, which basically satisfied the golden section line ratio. Moreover, the modification of snowflake-like AuPd/Cu₂S resulted in a significant increase in current by a factor of 1.48 compared to the bare electrode. Meanwhile, satellite-like Au/CeO₂ loaded methylene blue (MB) was also used as a signal probe, which has a high and stable current signal. Based on the above, a kanamycin (Kana) detection method based on AuPd/Cu₂S as a substrate and satellite-like Au/CeO₂ as a signal probe to improve the sensitivity of electrochemical sensor was designed. Detection of Kana was accomplished by changes in target concentration combined with Exonuclease III (Exo Ⅲ) assisted double cycling. Under optimal conditions, the sensor had a detection range of 0.001–1000 ng/mL and a detection limit of 0.299 pg/mL. Repeatability, reproducibility, specificity, stability and Kana in real and quality control samples were successfully verified using the sensor with satisfactory results.