# Combinatorial Synthesis of Protein–Polymer Conjugates by Postpolymerization Modification of Poly(pentafluorophenyl acrylate)s

## TL;DR

Scientists developed a method to quickly create protein-polymer combinations by modifying a polymer after it's made, which could be useful in various scientific and medical applications.

## Contribution

A modular combinatorial method for preparing protein–polymer conjugates via postpolymerization modification of PPFPA.

## Key findings

- Higher polymer:protein ratios improve conjugation efficiency for similarly soluble polymers.
- Polymers with more reactive groups or shorter hydrophilic side chains enhance protein conjugation.
- Smaller proteins conjugate more efficiently than larger ones.

## Abstract

Combinatorial methods for preparing polymeric biomaterials
enable
the rapid identification of materials useful for many applications
in science, medicine, and engineering. In the work described here,
we demonstrate that side-chain reactive polymers can be used as templates
for the rapid preparation of a small library of diversely functionalized
protein–polymer conjugates. The activated ester polymer poly­(pentafluorophenyl
acrylate) (PPFPA) was modified postpolymerization with substoichiometric
equivalents of three hydrophilic primary amines to yield a library
of amphiphilic, side-chain reactive copolymers. These copolymers were
then conjugated to two receptor-targeting proteins, holotransferrin
(hTF) and an engineered fibronectin-based protein (Fn3), through amine-activated
ester coupling. We investigated the influence of polymer:protein ratio,
side-chain chemistry (i.e., hydrophilic group identity and number
of protein-reactive groups), and protein identity on conjugation efficiencies.
Our results demonstrate that, for polymers of similar solubility in
aqueous media, a larger polymer:protein ratio yields higher conjugation
efficiencies. In addition, polymers with a greater number of reactive
groups or shorter hydrophilic side chains improve protein conjugation
efficiency. Finally, smaller proteins couple to the polymers more
efficiently than do larger proteins. Collectively, the results described
here demonstrate a modular approach for efficiently preparing bioconjugates
with diverse chemistries that may be of interest in a broad range
of applications.