High-Throughput, Protein-Targeted Biomolecular Detection Using Frequency-Domain Faraday Rotation Spectroscopy

Keywords

Brownian motion; Faraday effect; iron oxide nanoparticles; magnetic relaxation; magneto-optical characterization

Abstract

A clinically relevant magneto-optical technique (fd-FRS, frequency-domain Faraday rotation spectroscopy) for characterizing proteins using antibody-functionalized magnetic nanoparticles (MNPs) is demonstrated. This technique distinguishes between the Faraday rotation of the solvent, iron oxide core, and functionalization layers of polyethylene glycol polymers (spacer) and model antibody–antigen complexes (anti-BSA/BSA, bovine serum albumin). A detection sensitivity of ≈10 pg mL−1 and broad detection range of 10 pg mL−1 ≲ cBSA ≲ 100 µg mL−1 are observed. Combining this technique with predictive analyte binding models quantifies (within an order of magnitude) the number of active binding sites on functionalized MNPs. Comparative enzyme-linked immunosorbent assay (ELISA) studies are conducted, reproducing the manufacturer advertised BSA ELISA detection limits from 1 ng mL−1 ≲ cBSA ≲ 500 ng mL−1. In addition to the increased sensitivity, broader detection range, and similar specificity, fd-FRS can be conducted in less than ≈30 min, compared to ≈4 h with ELISA. Thus, fd-FRS is shown to be a sensitive optical technique with potential to become an efficient diagnostic in the chemical and biomolecular sciences.

Publication Date

3-28-2017

Publication Title

Small

Volume

13

Issue

12

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1002/smll.201602862

Socpus ID

85015966695 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85015966695

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