Mediator and label free estimation of stress biomarker using electrophoretically deposited Ag@AgO-polyaniline hybrid nanocomposite
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- 作者：Ajeet Kaushik ; Abhay Vasudev ; Sunil K. Arya ; Shekhar Bhansali
- 关键词：Ag@AgO-polyaniline nanocomposite ; Electrochemical immunosensing ; Cortisol (stress biomarkers) ; Point-of-care
- 刊名：Biosensors and Bioelectronics
- 出版年：2013
- 出版时间：15 December, 2013
- 年：2013
- 卷：50
- 期：Complete
- 页码：35-41
- 全文大小：1887 K
文摘
Cortisol, a steroid hormone, is an important biomarker for psychological stress and its detection is gaining prominence for personalized health monitoring. In present work, electrophoretically deposited nanocomposite films of polyaniline (PANI) and core-shell Ag@AgO nanoparticles (NP~5 nm) have been explored as an electro-active nanostructured platform for Anti-cortisol antibody (Anti-Cab) immobilization for electrochemical immunosensing of cortisol. Covalent binding of Anti-Cab onto Ag@AgO-PANI nanocomposite was achieved using EDC/NHS chemistry, which results in the amide bond formation between amino groups of PANI and COOH groups of anti-Cab. Nonspecific binding sites on the immunosensing electrodes were blocked using bovine serum albumin (BSA). The uniform distribution of electro-active and surface charged Ag@AgO NP in PANI matrix results in a nanoporous granular morphology (roughness~10 nm) that provides a functionalized conductive microenvironment for Anti-Cab immobilization. The BSA/Anti-Cab/Ag@AgO-PANI/Au bioelectrodes have been characterized using electrochemical impedance technique (EIS), cyclic voltammetric (CV) technique and atomic force microscopic (AFM) technique, respectively. In CV studies nanocomposite exhibited characteristic response current peak corresponding to AgO NP (0.25 V) with large magnitude of current response and resulted in high electron transport at the electrode-electrolyte interface without a mediator. Electrochemical response studies via CV for the fabricated BSA/Anti-Cab/Ag@AgO-PANI/Au immunosensor as a function of cortisol concentration exhibited a wide linear detection range of 1 pM-1 ¦ÌM, a detection limit of 0.64 pM mL?1(lower than ELISA), and high sensitivity 66 ¦ÌA M?1 with a regression coefficient of 0.998. The findings of present work may explore the application of Ag@AgO-PANI hybrid nanocomposite to detect cortisol and other biomarkers for point-of-care application.