Aptamer-functionalized screen-printed electrode coupled with graphene oxide and methylene blue nanocomposite as enhanced signal label for total arsenic determination in shellfish

Abstract

Abstract This work introduces an aptamer-functionalized screen-printed electrode (SPE) coupled with enhanced signal label for total arsenic (As) detection in shellfish, where total As is extracted with dry-ashing method and reduced to detectable As(III). Working electrode array is fabricated on a homemade SPE, proven to be superior to single electrode with equivalent modifications. Au nanoparticles (AuNPs) are electrodeposited onto the SPE to self-assemble As(III)-sensitive aptamer (Ars-3). As(III) response is successfully amplified with an enhanced signal label from the Ars-3/AuNPs/SPE, as provided by the synergistic effect between methylene blue (MB) and graphene oxide (GO). The modifications of AuNPs and Ars-3, as well as the incubation process of GO-MB nanocomposite, are examined by morphological and electrochemical methods. With optimizations of electrochemical setups and sample pretreatments, this method is adopted in a series of analyses with laboratorial and real samples. The limit of detection is 2 × 10−4 mg L-1, and the wide dynamic range up to 10 mg L-1 is well found. The Ars-3/AuNPs/SPE with the GO-MB signal label shows good reproducibility and long-term stability, and presents a high tolerance to possible interference ions. The applicability for real shellfish detection is confidently validated by different means as standard reference material, recovery test and certified ICP-MS.