Highly Chemiluminescent Magnetic Beads for Label-Free Sensing of 2,4,6-Trinitrotoluene

Abstract

Until now, despite the great success acquired in scientific research and commercial applications, magnetic beads (MBs) have been used for nothing more than a carrier in most cases in bioassays. In this work, highly chemiluminescent magnetic beads containing N-(4-aminobutyl)-N-ethyl isoluminol (ABEI) and Co (Co/ABEI/MBs) were first synthesized via a facile strategy. ABEI and Co were grafted onto the surface of carboxylated MBs by virtue of a carboxyl group and electrostatic interaction. The as-prepared Co/ABEI/MBs exhibited good paramagnetic properties, satisfactory stability, and intense chemiluminescence (CL) emission when reacted with HO, which was more than 150 times that of ABEI functionalized MBs. Furthermore, it was found that 2,4,6-trinitrotoluene (TNT) aptamer could attach to the surface of Co/ABEI/MBs via electrostatic interaction and coordination interaction between TNT aptamer and Co, leading to a decrease in CL intensity due to the catalytic site Co being blocked by the aptamer. In the presence of TNT, TNT would bind strongly with TNT aptamer and detach from the surface of Co/ABEI/MBs, resulting in partial restoration of the CL signal. Accordingly, label-free aptasensor was developed for the determination of TNT in the range of 0.05-25 ng/mL with a detection limit of 17 pg/mL. This work demonstrates that Co/ABEI/MBs are easily connected with recognition biomolecules, which are not only magnetic carriers but also direct sensing interfaces with excellent CL activity. It provides a novel CL interface with a magnetic property which easily separates analytes from the sample matrix to construct label-free bioassays.

Rational design of functional materials guided by single particle chemiluminescence imaging

“…CL-functionalized microbeads were prepared by incorporating N -(4-aminobutyl)- N -ethylisoluminol (ABEI) and Co 2+ into magnetic-polymer microbeads via covalent bonds and electrostatic interactions, respectively 39. The geometrical features and CL properties of the ensemble materials were subsequently characterized by multiple techniques including SEM, fluorescence spectroscopy, fluorescence microscopy and CL measurements with a CL meter.…”

“…The principle, condition optimization and interference test were conducted according to our previous publication (ESI†). 39 Briefly, microbeads were functionalized with aptamer molecules that can recognize a small molecule compound, TNT, which is one of the most classic explosives for military/terrorist purposes. The existence of analytes decreased the inhibition effect of the TNT aptamer on CL intensity, and led to enhanced CL emission upon injection of H 2 O 2 .…”

“…In a typical synthesis,39 6.0 mL of microbead suspension was washed thrice with 2-( N -morpholino)ethanesulfonic acid (MES) buffer after ultrasonication for 5 min. Subsequently, the suspension was dispersed in 6.0 mL of MES buffer containing 200 mg of EDC and 200 mg of NHS under vigorous stirring at room temperature.…”

“…Co-functionalization of catalysts in the same microenvironment further optimized the reaction efficiency and kinetics, leading to the state-of-the-art hydrogel materials that can emit intense CL light and last more than a week 35. Similar strategies have been also utilized to improve the sensitivity of CL assays for the detection of DNA, protein markers, metal ions and small molecular compounds 36–39. In these previous studies, although it was generally hypothesized that the microstructure of particles played essential roles in regulating the encapsulation and reaction efficiency of luminol analogues, a clear structure–activity relationship remained largely unexplored, thus hampering further improvements in the performance of these CL assays.…”

Practical Application of Aptamer-Based Biosensors in Detection of Low Molecular Weight Pollutants in Water Sources

“…This sensor obtained a range from 0.05 to 25 ng·mL −1 with a LOD of 17 pg·mL −1 . Moreover, its specificity was examined against four interfering compounds including NB, 2′NT, 3′NT and 2,4′DNT, they were showed a weak CL single response compared to the target of TNT [ 116 ]. For other compounds in water sources, an aptamer-based biosensor for label-free detection of ethanolamine by electrochemical (EA) impedance spectroscopy has been reported.…”