Single-Atomic Site Catalyst Enhanced Lateral Flow Immunoassay for Point-of-Care Detection of Herbicide

Abstract

Point-of-care (POC) detection of herbicides is of great importance due to their impact on the environment and potential risks to human health. Here, we design a single-atomic site catalyst (SASC) with excellent peroxidase-like (POD-like) catalytic activity, which enhances the detection performance of corresponding lateral flow immunoassay (LFIA). The iron single-atomic site catalyst (Fe-SASC) is synthesized from hemin-doped ZIF-8, creating active sites that mimic the Fe active center coordination environment of natural enzyme and their functions. Due to its atomically dispersed iron active sites that result in maximum utilization of active metal atoms, the Fe-SASC exhibits superior POD-like activity, which has great potential to replace its natural counterparts. Also, the catalytic mechanism of Fe-SASC is systematically investigated. Utilizing its outstanding catalytic activity, the Fe-SASC is used as label to construct LFIA (Fe-SASC-LFIA) for herbicide detection. The 2,4-dichlorophenoxyacetic acid (2,4-D) is selected as a target here, since it is a commonly used herbicide as well as a biomarker for herbicide exposure evaluation. A linear detection range of 1-250 ng/mL with a low limit of detection (LOD) of 0.82 ng/mL has been achieved. Meanwhile, excellent specificity and selectivity towards 2,4-D have been obtained. The outstanding detection performance of the Fe-SASC-LFIA has also been demonstrated in the detection of human urine samples, indicating the practicability of this POC detection platform for analyzing the 2,4-D exposure level of a person. We believe this proposed Fe-SASC-LFIA has potential as a portable, rapid, and high-sensitive POC detection strategy for pesticide exposure evaluation.

Engineering Atomic Single Metal–FeN4Cl Sites with Enhanced Oxygen-Reduction Activity for High-Performance Proton Exchange Membrane Fuel Cells

“…35 In Figure 2a, no Fe−Fe scattering component at 2.2 Å is found in the Fourier-transformed EXAFS (FT-EXAFS) curves of FeN 4 Cl SAC and FeN x SAC, demonstrating no metallic Fe cluster and/or nanocrystal exist. 36 The main peak of FeN x SAC is aligned with the Fe− N peak in the FePc reference sample, suggesting that Fe is dispersed as a single atom formed with Fe−N bonding. 37 In comparison, FeN 4 Cl SAC shows a scattering path at about 1.6 S1, showing the coordination number of Fe in FeN 4 Cl SAC can be five, with one Cl atom coordinating with a single Fe atom perpendicular to the Fe−N 4 plane (inset of Figure 2b), which is similar to that of hemin Cl.…”

“…The FeN 4 Cl SAC shows a small shift to lower energy in the rising edge region compared with that of the FeN x SAC, which is due to the Cl atom directly tuning the iron electron density . In Figure a, no Fe–Fe scattering component at 2.2 Å is found in the Fourier-transformed EXAFS (FT-EXAFS) curves of FeN 4 Cl SAC and FeN x SAC, demonstrating no metallic Fe cluster and/or nanocrystal exist . The main peak of FeN x SAC is aligned with the Fe–N peak in the FePc reference sample, suggesting that Fe is dispersed as a single atom formed with Fe–N bonding .…”

Single-atom catalysts: promotors of highly sensitive and selective sensors

“…To build a portable and rapid point-of-care detection platform for the 2,4-dichlorophenoxyacetic acid (2,4-D, a herbicide) exposure evaluation, Lin's group designed a Fe SAC to enhance the performance of lateral flow immunoassay (LFIA). 198 In the presence of 2,4-D, it would specifically interact with the Fe SAs tagged 2,4-D antibodies to prevent them from attaching to the pre-adsorbed haptens (BSA) on the test lines, resulting in a fading label (Fig. 20e).…”

Post-Assay Chemical Enhancement for Highly Sensitive Lateral Flow Immunoassays: A Critical Review

“…These directions partly align with the developments of fundamental nanozymology [ 183 ]. Increasing the catalytic activity can be achieved by optimization of the chemical composition of nanozymes [ 102 , 171 , 188 , 231 ], creating surface-dispersed catalytic centers [ 101 , 162 ] or single-atom catalysts [ 232 , 233 ]. Nanozymes with surface-dispersed catalytic centers [ 234 ] and single-atom catalysts have high catalytic activity and low consumption of precious precursors [ 235 ], making them a prospective label for LFIA and other bioanalytical methods.…”