Modelling refractive index changes due to molecular interactions

Manoj Varma

doi:10.1117/12.2211662

9 March 2016 Modelling refractive index changes due to molecular interactions

Manoj Varma

Proceedings Volume 9719, Biophysics, Biology, and Biophotonics: the Crossroads; 97190D (2016) https://doi.org/10.1117/12.2211662
Event: SPIE BiOS, 2016, San Francisco, California, United States

Abstract

There are a large number of sensing techniques which use optical changes to monitor interactions between molecules. In the absence of fluorophores or other labels, the basic signal transduction mechanism relies on refractive index changes arising from the interactions of the molecules involved. A quantitative model incorporating molecular transport, reaction kinetics and optical mixing is presented which reveals important insights concerning the optimal detection of molecular interactions optically. Although conceptually simple, a comprehensive model such as this has not been reported anywhere. Specifically, we investigate the pros and cons of detecting molecular interactions in free solution relative to detecting molecular interactions on surfaces using surface bound receptor molecules such as antibodies. The model reveals that the refractive index change produced in surface based sensors is 2-3 orders of magnitude higher than that from interactions in free solution. On the other hand, the model also reveals that it is indeed possible to distinguish specific molecular interactions from non-specific ones based on free-solution bulk refractometry without any washing step necessary in surface based sensors. However, the refractive index change for free solution interactions predicted by the model is smaller than 10^-7 RIU, even for large proteins such as IgG in sufficiently high concentrations. This value is smaller than the typical 10^-6 RIU detection limit of most state of the art optical sensing techniques therefore requiring techniques with substantially higher index sensitivity such as Back Scattering Interferometry.

Conference Presentation

Citation Download Citation

Manoj Varma "Modelling refractive index changes due to molecular interactions", Proc. SPIE 9719, Biophysics, Biology, and Biophotonics: the Crossroads, 97190D (9 March 2016); https://doi.org/10.1117/12.2211662

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available