Thionin functionalized signal amplification label derived dual-mode electrochemical immunoassay for sensitive detection of cardiac troponin I

• Published in: Biosensors & bioelectronics Vol. 133; pp. 72 - 78
• Main Authors: Lv, Hui, Li, Yueyun, Zhang, Xiaobo, Li, Xinjin, Xu, Zhen, Chen, Lei, Li, Degang, Dong, Yunhui
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 15-05-2019
• Subjects: Amperometric i-t; Cardiac troponin I; Differential pulse voltammetry; Double signal label; Sandwich-type electrochemical immunosensor; Double signal label; Cardiac troponin I; Sandwich-type electrochemical immunosensor; Amperometric i-t; Differential pulse voltammetry
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2019.03.033

A sensitive sandwich-type electrochemical immunosensor was established by employing Au@Pt core-shell multi-branched nanoparticles, and thionin functionalized nitrogen/sulfur co-doped graphene oxide (N/S-cGO/L-lys/Au@Pt MBs/Thi) as a double signal label to detect cardiac troponin I (cTnI). In this work, Au nanorods functionalized polydopamine (Au NR@PDA) with high adsorption capacity and superior electroconductivity can provide an efficient substrate for immobilizing primary antibodies (Ab1). In the proposed N/S-cGO/L-lys/Au@Pt MBs/Thi, an electrochemically active molecule, Thi was covalently bonded in the N/S-cGO/L-lys/Au@Pt MBs. It presented a strong differential pulse voltammetry (DPV) current signal without electron transfer mediators, and showed a high electrocatalytic activity toward H2O2 reduction by using amperometric i-t (i-t). Impressively, with the synergistic effect of N/S-cGO/L-lys/Au@Pt MBs/Thi and Au NR@PDA, the developed dual-mode electrochemical immunosensor for cTnI detection showed a wide linear concentration range (50 fg/mL to 250 ng/mL, 750 fg/mL to 100 ng/mL) and a low detection limit (16.7 fg/mL, 250 fg/mL) via i-t and DPV, respectively. Furthermore, this immunosensor exhibited acceptable reproducibility, high sensitivity and good stability under optimal conditions. More importantly, the satisfactory results were obtained in detection of cTnI-spiked human serum samples, and the presented method may be a promising application in clinical bioanalysis.
•The dual-mode electrochemical immunosensor for sensitive detection cTnI via amperometric i-t and DPV.•Au NR@PDA with good conductivity and biocompatibility were modified on GCE to immobilize Ab1.•N/S-cGO/L-lys/Au@Pt MBs/Thi exhibited better peroxidase-like property, and directly acted as electroactive substance.•The immunosensor showed acceptable reproducibility, high sensitivity and good stability.
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