# Plasmonic bio-sensing for the Fenna-Matthews-Olson complex

## TL;DR

This paper explores the use of plasmonic nanowire sensors to detect local modifications in the Fenna-Matthews-Olson complex by analyzing changes in scattering spectra, offering a new method for bio-sensing at the molecular level.

## Contribution

It introduces a theoretical framework for using metal nanowire surface plasmons to monitor site-specific changes in the FMO complex, highlighting the detection of local defects or mutations.

## Key findings

- Variations in excitation transfer rates affect scattering spectra.
- Changing plasmon-site coupling ratios enhances detection sensitivity.
- Site 5 exhibits a distinct Fano lineshape in spectra.

## Abstract

We study theoretically the bio-sensing capabilities of metal nanowire surface plasmons. As a specific example, we couple the nanowire to specific sites (bacteriochlorophyll) of the Fenna-Matthews-Olson (FMO) photosynthetic pigment protein complex. In this hybrid system, we find that when certain sites of the FMO complex are subject to either the suppression of inter-site transitions or are entirely disconnected from the complex, the resulting variations in the excitation transfer rates through the complex can be monitored through the corresponding changes in the scattering spectra of the incident nanowire surface plasmons. We also find that these changes can be further enhanced by changing the ratio of plasmon-site couplings. The change of the Fano lineshape in the scattering spectra further reveals that "site 5" in the FMO complex plays a distinct role from other sites. Our results provide a feasible way, using single photons, to detect mutation-induced, or bleaching-induced, local defects or modifications of the FMO complex, and allows access to both the local and global properties of the excitation transfer in such systems.