# Photosystem I Photopolymerizes Pyrrole into Spherical Nanocomposites

## TL;DR

This paper shows how Photosystem I can be used to create conductive polymer nanocomposites for efficient electron transfer.

## Contribution

A new method using Photosystem I to photopolymerize pyrrole into spherical nanocomposites is introduced.

## Key findings

- Photosystem I's P700 site polymerizes pyrrole into a conductive molecular wire.
- The resulting nanocomposites encapsulate the protein in conductive polymer nanoparticles.
- Electron microscopy and electrochemical techniques confirmed the nanocomposites' properties.

## Abstract

Conductive polymers have been shown to be an effective
scaffold
for proteins when designing bioelectrochemical systems, particularly
for the Photosystem I protein. Utilization of synthetic polymer chemistry
has allowed a great deal of tunability within the protein/polymer
interface to improve electron transfer from the proteins, ultimately
progressing toward direct electron transfer from the active sites.
Seeking to address this issue, a new heterogeneous approach is presented
to synthesize Photosystem I/polypyrrole (PSI/PPy) composites. The
oxidative potential of PSI’s P700 reaction site
was leveraged to polymerize pyrrole into a molecular wire, providing
a more efficient means of electron transfer to the protein. Over the
course of several hours of photopolymerization of Py in a PSI film,
PPy not only wired PSI but began incasing the protein within conductive
polymer nanoparticles. These resulting composite nanoparticles were
extensively characterized by electron microscopy and electrochemical
techniques to showcase their synergistic properties.