Curcumin-graphene quantum dots for dual mode sensing platform: Electrochemical and fluorescence detection of APOe4, responsible of Alzheimer's disease

New dual electrochemical and fluorescence sensitive curcumin-graphene quantum dots sensing platform coated on the transparent Indium-Tin-Oxide electrode was developed to sense APOe4 DNA, responsible of Alzheimer's disease. Curcumin molecule with its dual fluorescence and electrochemical properties was electropolymerized on GQDs-ITO surface. EDC/NHS chemistry was used to covalently immobilize an amino-substituted DNA probe via a malonic acid spacer. Quenching of curcumin signals following hybridized DNA complex was employed to quantify APOe4 DNA. Amperometric studies revealed an ul-trasensitive behavior toward the formation of DNA complex with a sensitivity of 4.74 nA.mL.pg (-1) and a limit of detection as low as 0.48 pg mL (-1). The platform exhibits very good performances such as repeatability, reproducibility, selectivity and long storage stability. Fluorescence results were established for the support and the complementarity of electrochemical results. Founded results confirmed the ultrasensitivity of platform with comparable performances. Recorded results in human blood plasma demonstrated the high efficacy of curcumin system sensing even in the clinical matrix. (c) 2018 Elsevier B.V. All rights reserved.