Amplified Magnetic Resonance Sensing via Enzyme-Mediated Click Chemistry and Magnetic Separation

Abstract

Magnetic resonance sensing (MRS) assays with simple pretreatment have drawn increasing attention for the development of biosensors, whereas conventional MRS is not competent for analyzing trace targets due to its relative low sensitivity. In this work, we employ alkaline phosphatase-mediated click chemistry as a signal transformation and amplification technique that effectively enhances the magnetic signal for amplified MRS. We outline two strategies by modulating either the aggregation state or the number of the magnetic probes based on click chemistry-triggered aggregation of nanoparticles and their ability for magnetic separation. The experimental results show that the combination of magnetic nanoprobe number-based modulation and magnetic separation outcompetes nanoprobe aggregation-based strategy for an enhanced sensitivity, providing an attractive platform for MRS-based analysis of small molecules. For proof of application, we apply this click chemistry-based approach for the detection of clenbuterol, an illegally used drug to promote growth in livestock. It shows a linear detection range from 0.1 ng mL −1 to 500 ng mL −1 with a limit of detection of 0.02 ng mL −1 , revealing that the click chemistry-mediated amplified MRS can act as a promising magnetic platform to detect trace levels of small molecules in authentic samples.

Bioinspired Artificial “Clickase” for the Catalytic Click Immunoassay of Foodborne Pathogens

“…Copper­(I)-catalyzed azide–alkyne cycloaddition (CuAAC) as a revolutionary biorthogonal click chemistry reaction has been extensively applied in biochemical assays due to its merits of high reaction speed, mild reaction conditions, good selectivity, and high efficiency. − To date, the enzyme-like click catalysis mediated by copper nanoparticles (CuNPs) has been successfully integrated with the CuAAC click reaction for developing various CuAAC-based assays, such as fluorescence assays, − magnetic resonance sensing (MRS) assays, colorimetric assays, SERS immunoassays, and electro-click assays . However, the reported solid CuO NPs used in the catalytic click reactions suffer from a high diffusion barrier, resulting in limited catalytic activity.…”

Magnetic Relaxation Switch Biosensors Based on Self-Assembly of Polystyrene Microspheres and Magnetic Nanoparticles for Detection of Bisphenol A

“…14 A magnetic relaxation switching (MRS) sensor was recently developed based on the "spin−spin" relaxation time (T 2 ) change of water protons originating from the state change of magnetic nanoparticles (dispersion or aggregation). 15 The MRS sensor can detect the target in the opaque samples with one step, and it is not limited by multiple washing steps or light-based interference. 16 However, it is difficult to detect small molecules by conventional MRS owing to their limited binding sites, which cannot significantly change the state of MNPs and generate a strong relaxation signal.…”

“…A magnetic relaxation switching (MRS) sensor was recently developed based on the “spin–spin” relaxation time ( T 2 ) change of water protons originating from the state change of magnetic nanoparticles (dispersion or aggregation) . The MRS sensor can detect the target in the opaque samples with one step, and it is not limited by multiple washing steps or light-based interference .…”

Highly Sensitive Homogeneous Electrochemiluminescence Biosensor for Alkaline Phosphatase Detection Based on Click Chemistry-Triggered Branched Hybridization Chain Reaction

“…For example, Jiang et al designed a naked-eye readable plasma nanosensor using ALP-triggered agglomeration of gold nanoparticles and demonstrated its potential in immunoassay applications . Applying the ALP-labeled antibody to the immune sandwich structure and employing the same mechanism, Wu and co-workers established a magnetic resonance sensing-based immunoassay platform for the detection of small molecules . Early studies indicated that the cyclization reaction between the specially designed 5′-azide and 3′-alkyne tagged padlock probes through CuAAC can produce a relatively long single-stranded DNA (ssDNA), which nearly has the same capability as a normal ssDNA and has been used to trigger hyperbranched rolling circle amplification (HRCA) and produce large amounts of double-stranded DNAs (dsDNAs) with high efficiency .…”

“…20 platform for the detection of small molecules. 21 Early studies indicated that the cyclization reaction between the specially designed 5′-azide and 3′-alkyne tagged padlock probes through CuAAC can produce a relatively long single-stranded DNA (ssDNA), which nearly has the same capability as a normal ssDNA and has been used to trigger hyperbranched rolling circle amplification (HRCA) and produce large amounts of double-stranded DNAs (dsDNAs) with high efficiency. 22 Since the addition of SYBR Green I in a dsDNA solution can produce enhanced fluorescence, this had been applied to develop a highly sensitive fluorescence biosensor for inorganic pyrophosphatase detection.…”