Identification of Toxin Inhibitors Using a Magnetic Nanosensor‐Based Assay

Abstract

A magnetic nanosensor-based method is described to screen a library of drugs for potential binding to toxins. Screening is performed by measuring changes in the magnetic relaxation signal of the nanosensors (bMR nanosensors) in aqueous suspension upon addition of the toxin. The Anthrax lethal factor (ALF) is selected as a model toxin to test the ability of our bMR nanosensor-based screening method to identify potential inhibitors of the toxin. Out of 30 molecules screened, sulindac, naproxen and fusaric acid are found to bind LF, with dissociation constants in the low micromolar range. Further biological analysis of the free molecules in solution indicate that sulindac and its metabolic products inhibited LF cytotoxicity to macrophages with IC50 values in the micromolar range. Meanwhile, fusaric acid is found to be less effective at inhibiting LF cytotoxicity, while naproxen does not inhibit LF toxicity. Most importantly, when the sulindac and fusaric acid-bMR nanosensors themselves are tested as LF inhibitors, as opposed to the corresponding free molecules, they are stronger inhibitors of LF with IC50 values in the nanomolar range. Taken together, these studies show that a bMR nanosensors-based assay can be used to screen known drugs and other small molecules for inhibitor of toxins. The method can be easily modified to screen for inhibitors of other molecular interactions and not only the selected free molecule can be study as potential inhibitors but also the bMR nanosensors themselves achieving greater inhibitory potential.

Public-Health-Driven Microfluidic Technologies: From Separation to Detection

“…In the past few decades, the magnetic phenomenon of magnetic materials has been widely concerned, which is used to realize the sensitive detection of analytes [196]. Compared to the optical detection method, the magnetic detection method has advantages of low cost and high detection efficiency because of the elimination of expensive optical elements and the use of a magnetic field to shorten the sample preparation time [197,198]. Moreover, because biological samples have few magnetic background signals which can be ignored, the magnetic detection method has high specificity, sensitivity, and signal-to-noise ratio [199].…”

Homogeneous Biosensing Based on Magnetic Particle Labels

“…For example, hormone-like bisphenol A molecules have been tested in drinking water with a LoD of 400 pg/mL [ 208 ], enantiomeric impurities in solutions of the amino acid phenylalanine have been examined [ 209 ], and the salbutamol drug has been measured in swine urine samples [ 210 ]. Identification of inhibitors for toxins released by the Anthrax bacterium by measurements of the T 2 relaxation time has also been reported [ 211 ]. In a suitable measurement setting, MRSw can also be applied to detect ions in solution, which has been shown by Atanasijevic et al , who detected calcium ions by applying calcium dependent protein-protein interactions to induce magnetic NP agglomeration [ 212 ].…”

A Comparison of Optical, Electrochemical, Magnetic, and Colorimetric Point-of-Care Biosensors for Infectious Disease Diagnosis

“…Magnetic nanoparticles have been utilized in several studies to create potential POC diagnostic platforms for the detections of E. coli, 55,105 influenza, 106 S. typhimurium, S. aureus, 105 and anthrax. 107 Using superparamagnetic iron oxide nanoparticles, Shelby et al 106 designed biosensors capable of detecting and differentiating between influenza glycoproteins. The nanoparticle platform used in this approach is based upon a magnetic iron core surrounded by a poly(acrylic acid) coating.…”

“…Magnetic nanoparticles have been utilized in several studies to create potential POC diagnostic platforms for the detections of E. coli , , influenza, S. typhimurium , S. aureus , and anthrax …”