# Supramolecular Polymer Bottlebrushes: In Situ Assessment of Noncovalent Assemblies in Human Serum by Analytical Ultracentrifugation

## TL;DR

This study uses analytical ultracentrifugation to assess the stability and behavior of supramolecular polymer bottlebrushes in human serum over time.

## Contribution

The work introduces a method to track noncovalent polymer assemblies in human serum using a Cy5 label and AUC.

## Key findings

- SPBs remain stable in human serum for over a month at body temperature.
- Some Cy5 dye molecules interact with human serum albumin (HSA).

## Abstract

For nanomedical targeting and drug delivery purposes, the noncovalent assembly of polymer building blocks into defined nanostructures is an intense area of research. One of the key assets desirable to know for the potential nanocarrier is the stability under conditions close to those in application scenarios. Here, a series of polymer building blocks based on poly(ethylene glycol) (PEG), which comprise a functional end group facilitating self‐assembly into supramolecular polymer bottlebrushes (SPBs), is hydrodynamically studied. The building blocks, and consequently the assemblies, are labeled with a cyanine5 (Cy5) dye enabling selective tracing of the materials in human serum (HS) in analytical ultracentrifugation (AUC) experiments. Our experiments reveal a long‐term stability of the noncovalent assemblies over one month of storage of the materials in HS at body temperature. At the same time, the interaction of some of the Cy5 moieties with the transport protein human serum albumin (HSA) is evidenced.

The integrity of supramolecular polymer bottlebrushes (SPBs) with envisaged stealth properties is investigated using analytical ultracentrifugation (AUC) at conditions close to the application scenario. Selective tracking of the SPBs in human serum (HS) via the Cyanine5 (Cy5) label, revealed long‐term stability at body temperature as well as interaction of dye with human serum albumin (HSA).