Detection Limit for Optically Sensing Specific Protein Interactions in Free-solution

01 December 2017, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Optical molecular sensing techniques are often limited by the refractive index change associated with the probed interactions. In this work, we present a closed form analytical model to estimate the magnitude of optical refractive index change arising from protein-protein interactions. The model, based on the Maxwell Garnett effective medium theory and first order chemical kinetics serves as a general framework for estimating the detection limits of optical sensing of molecular interactions. The model is applicable to situations where one interacting species is immobilized to a surface, as commonly done, or to emerging techniques such as Back-Scattering Interferometry (BSI) where both interacting species are un-tethered. Our findings from this model point to the strong role of as yet unidentified factors in the origin of the BSI signal resulting in significant deviation from linear optical response.

Keywords

Free solution protein detection
Maxwell Garnet effective index theory
Refractive index change with protein interactions
Effect of shape and size of proteins
Detection limit of protein biosensors
Molecular sensors
theory of sensing
Chemistry

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