Magnetic nanosensors for highly sensitive and selective detection of bacillus Calmette-Guérin

Abstract

With current concerns of the global threat from tuberculosis, it has become important to rapidly identify the bacteria. Traditional technologies involving isolation and amplification of the pathogenic bacteria are complicated and time-consuming. In this work, we describe a sensitive NMR-based detection method to identify bacteria via bacteria-induced self-assembly of magnetic nanoparticles. Bacillus Calmette-Guérin (BCG) was used as a surrogate for Mycobacterium tuberculosis. We prepared the probes by covalent immobilization of the anti-BCG monoclonal antibody onto carboxylic acid-functionalized magnetic nanoparticles. Once a solution containing BCG was introduced, the probes switched from a well dispersed state to an aggregated one, leading to a distinct and dose-dependent change in the spin-spin relaxation time (T2) of the solution. Thus the qualitative and quantitative detection method for BCG was established. The method provides specific detection of as few as 8 bacterial cells per millilitre in experimental samples within 1 hour, which will be promising for rapid detection of M. tuberculosis in clinical samples.

Magnetic Relaxation Switching Assay Using IFNα-2b-Conjugated Superparamagnetic Nanoparticles for Anti-Interferon Antibody Detection

“…Recent decades have shown that the use of nanoscale preparations allows for highly sensitive detection of various chemicals and bioligands (e.g., peptides, proteins, antibodies, viral particles, antibiotics, mRNA, etc.) in biological fluids in real time [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ]. MPs were synthesized through the chemical coprecipitation of ferrous (Fe 2+ ) and ferric (Fe 3+ ) chloride and coated with a 10 kDa dextran via the cross-link with epicholorohydrin.…”

Recent advances in biological detection with magnetic nanoparticles as a useful tool

“…To meet this challenge, a sensitive NMR-based detection method to identify bacteria via bacteria-induced selfassembly of MNPs was developed by Liang et al [73]. With a detection limit of as few as 8 bacteria cells per mL in experimental samples within 1 h, the method showed great potential for rapid detection of M. tuberculosis in clinical samples.…”

A magnetic relaxation switching immunosensor for one-step detection of salbutamol based on gold nanoparticle–streptavidin conjugate

“…Recently, magnetic relaxation switching (MRS) sensors that depend on target-induced aggregation (or disaggregation) of superparamagnetic nanoparticles (SMNs) are employed to quantify a wide range of targets. [9][10][11] In a typical MRS sensor, the target can induce a change in the state of the SMNs (from dispersed to aggregated) via specic donor-receptor recognition, and this state change of the SMNs induces a heterogeneous magnetic eld, which affects the transverse relaxation time (T 2 ) of surrounding water molecules. The DT 2 value (the change of T 2 ) is related to the degree of aggregation of the SMNs, and this degree of aggregation is dependent on the amount of target in the sample; thus, DT 2 can be employed as a signal readout.…”