NZVI©Au magnetic nanocomposite‐based electrochemical magnetoimmunosensing for ultrasensitive detection of troponin‐T cardiac biomarker

Abstract

Early, inexpensive, reliable, and accurate diagnosis of cardiovascular abnormalities has become of crucial importance to prevent and halt their progression. Herein, we report a label‐free electrochemical magnetoimmunosensing for monitoring cardiac diseases through qualitative and quantitative detection of cardiac troponin‐T (Tpn‐T) in aqueous solution. In this context, a nanocomposite of gold nanoparticles coated a magnetic nanoscale zero‐valent iron core (NZVI©Au) is employed as a substrate to facilitate the electron transfer and to bind more primary Tpn‐T antibodies. The immunosensing platform consists of an anti‐cardiac troponin‐T antibody (Tpn‐T‐ab) modified NZVI©Au magnetic membrane attached onto a boron doped diamond (BDD) electrode. Sensing experiments were performed by the imposition of an external magnetic field at the backside of the electrode. The sensor response was performed using impedimetric assays, wherein the increase in the electron transfer resistance (Rct) correlated with an increase in the concentration of Tpn‐T. Linearity was obtained in the range from 1 to 109 fg/mL with a detection limit of 0.354 fg/mL. The proposed platform exhibited high selectivity, high reproducibility, and good stability, while retaining more than 90% of the sensitivity after 2 weeks of storage at 4°C. The determination of Tpn‐T is well compared with previously reported methods and has been successfully tested in serum samples. This encouraging result suggests that the developed sensing strategy provides a high potential for the early assessment of Tpn‐T in point‐of‐care testing applications.

High Performance Non-Enzymatic Electrochemical Lactate Sensor Based on ZnAl Layered Double Hydroxide Nanosheets Supported Gold Nanoparticles

“…3b, a formation of small sized AuNPs is evident by the appearance of an absorption peak at a wavelength of approximately 520 nm, characteristic of the surface plasmon resonance (SPR) effect of the gold nanocrystals. 42 Figure 3c displays the microscopic image of the surface morphology of the AuNPs obtained using TEM visualization. Most of the AuNPs were of spherical shape and are well dispersed with an average diameter of 14 ± 1 nm (Fig.…”

“…Prior to the fabrication, the BDD electrode has been subjected to a polarization step at −3.0 V in 0.5 M H 2 SO 4 for 3 min to improve electrode kinetics and achieve accurate and reproducible measurements results. 41,42 After this, the ZnAl LDH nanosheets were assembled alternately with AuNPs on the surface of the BDD in a drop-wise manner. Typically, the assembly was performed by casting the BDD substrate with 50 μl of positively charged LDH nanosheets and 50 μl of negatively charged AuNPs colloidal suspension, while leaving each of them 10 min in desiccator, followed by thorough rinsing with EDC (0.4 M)/NHS (0.1 M) and utrapurified water in order to activate the surface of the supported AuNPs.…”