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Merck
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Holographic molecular binding assays.

Scientific reports (2020-02-08)
Yvonne Zagzag, M Francesca Soddu, Andrew D Hollingsworth, David G Grier
ABSTRACT

We demonstrate that holographic particle characterization can directly detect binding of proteins to functionalized colloidal probe particles by monitoring the associated change in the particles' size. This label-free molecular binding assay uses in-line holographic video microscopy to measure the diameter and refractive index of individual probe spheres as they flow down a microfluidic channel. Pooling measurements on 104 particles yields the population-average diameter with an uncertainty smaller than 0.5 nm, which is sufficient to detect sub-monolayer coverage by bound proteins. We demonstrate this method by monitoring binding of NeutrAvidin to biotinylated spheres and binding of immunoglobulin G to spheres functionalized with protein A.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
N,N-Dimethylformamide, anhydrous, 99.8%
Sigma-Aldrich
IgG, Rabbit, Rabbit IgG Polyclonal Antibody validated for use in ELISA.
Sigma-Aldrich
Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), average Mn ~14,600