High‐Throughput,Protein‐Targeted Biomolecular Detection Using Frequency‐Domain Faraday Rotation Spectroscopy |
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| Authors: | Richard J Murdock Shawn A Putnam Soumen Das Ankur Gupta Elyse D Z Chase Sudipta Seal |
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| Affiliation: | 1. Health Sciences and Technology (HST), Institute for Medical Engineering and Science (IMES), Massachusetts Institute of Technology and Harvard University, Cambridge, MA, USA;2. Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL, USA;3. Department of Materials Science and Engineering, Advanced Materials Processing and Analysis Center, (AMPAC), Nanoscience Technology Center (NSTC), University of Central Florida, Orlando, FL, USA;4. Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA, USA |
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| 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 µ g 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. |
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| Keywords: | Brownian motion Faraday effect iron oxide nanoparticles magnetic relaxation magneto‐optical characterization |
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