Electrochemical Biosensor Composed of Silver Ion-Mediated dsDNA on Au-Encapsulated Bi 2 Se 3 Nanoparticles for the Detection of H 2 O 2 Released from Breast Cancer Cells.

A newly developed electrochemical biosensor composed of a topological insulator (TI) and metallic DNA (mDNA) is fabricated. The bismuth selenide nanoparticle (Bi2Se3 NP) is synthesized and sandwiched between the gold electrode and another Au-deposited thin layer (Bi2Se3@Au). Then, eight-silver-ion mediated double-stranded DNA (mDNA) is immobilized onto the substrate (Bi2Se3@Au-mDNA) for the further detection of hydrogen peroxide. The Bi2Se3 NP acts as the electrochemical-signal booster, while unprecedentedly its encapsulation by the Au thin layer keeps the TI surface states protected, improves its electrochemical-signal stability and provides an excellent platform for the subsequent covalent immobilization of the mDNA through Au-thiol interaction. Electrochemical results show that the fabricated biosensor represents much higher Ag+ redox current (approximate to 10 times) than those electrodes prepared without Bi2Se3@Au. The characterization of the Bi2Se3@Au-mDNA film is confirmed by atomic force microscopy, scanning tunneling microscopy, and cyclic voltammetry. The proposed biosensor shows a dynamic range of 00.10 x 10(-6) M to 27.30 x 10(-6) M, very low detection limit (10 x 10(-9) M), unique current response (1.6 s), sound H2O2 recovery in serum, and substantial capability to classify two breast cancer subtypes (MCF-7 and MDA-MB-231) based on their difference in the H2O2 generation, offering potential applications in the biomedicine and pharmacology fields.