Application of Europium Multiwalled Carbon Nanotubes as Novel Luminophores in an Electrochemiluminescent Aptasensor for Thrombin Using Multiple Amplification Strategies

Abstract

A novel electrochemiluminescent (ECL) aptasensor was proposed for the determination of thrombin (TB) using exonuclease-catalyzed target recycling and hybridization chain reaction (HCR) to amplify the signal. The capture probe was immobilized on an Au-GS-modified electrode through a Au-S bond. Subsequently, the hybrid between the capture probe and the complementary thrombin binding aptamer (TBA) was aimed at obtaining double-stranded DNA (dsDNA). The interaction between TB and its aptamer led to the dissociation of dsDNA because TB has a higher affinity to TBA than the complementary strands. In the presence of exonuclease, aptamer was selectively digested and TB could be released for target recycling. Extended dsDNA was formed through HCR of the capture probe and two hairpin DNA strands (NH2-DNA1 and NH2-DNA1). Then, numerous europium multiwalled carbon nanotubes (Eu-MWCNTs) could be introduced through amidation reaction between NH2-terminated DNA strands and carboxyl groups on the Eu-MWCNTs, resulting in an increased ECL signal. The multiple amplification strategies, including the amplification of analyte recycling and HCR, and high ECL efficiency of Eu-MWCNTs lead to a wide linear range (1.0×10(-12)-5.0×10(-9) mol/L) and a low detection limit (0.23 pmol/L). The method was applied to serum sample analysis with satisfactory results.

Poly-Phthalocyanine–Doped Graphene Oxide Nanosheet Conjugates for Electrocatalytic Oxidation of Drug Residues

“…The potential at which to perform EIS studies was determined by cyclic voltammetry to be 0.3 V. The EIS parameters were obtained by fitting the Randles equivalent circuit (inset in Figure 4 ) to the experimental data and performing complex non-linear least-squares procedures available in an EIS data fitting computer program. The behavior of probes under electrochemical impedance studies is known to exhibit two sections: the circular part which is associated with resistance to charge transfer behavior and the straight line component associated with diffusion of redox materials toward the electrode surface ( Wu et al, 2015 ). The higher the radius of the circle, the higher the difficulty with which the probe can facilitate redox reactions.…”

“…This makes the probe very applicable in biological media since the two analytes coexist in physiological environments ( Wu et al, 2015 ). To further ascertain non-interference between the two, the concentrations of the two were independently varied and the results were observed ( Figure 8 ).…”

The Role of Temperature on the Degree of End-Closing and Filling of Single-Walled Carbon Nanotubes

“…Herein, we perform a systematic study to understand the role of temperature on the degree of end-closing of SWCNTs and filling yield when carbon nanotubes are filled with EuCl 3 by molten phase capillary wetting. Europium-CNT hybrids have received attention due to the luminescent properties that europium confers to the system [38][39][40].…”

Label‐Free Electrochemiluminescence Aptasensor for Highly Sensitive Detection of Acetylcholinesterase Based on Au‐Nanoparticle‐Functionalized g‐C3N4 Nanohybrid

“…In recent years, nanomaterial‐based ECL sensors have attracted great attention because of their unique electronic, optical, and thermal properties, leading to excellent application in environment, energy and bioanalytical fields, especially in the design of aptasensor . Among all kinds of nanomaterials, graphite‐like carbon nitride (g‐C 3 N 4 ) has sparked a surge of research interest due to its particular properties, for instance, large surface area, good biocompatibility, strong ECL intensity and good chemical stability .…”