Imaging Single-Chain Nanoparticle Folding via High-Resolution Mass Spectrometry

Area of Science:

• Polymer Chemistry
• Supramolecular Chemistry
• Analytical Chemistry

Background:

• Single-chain nanoparticles (SCNPs) are formed by collapsing individual polymer chains.
• Understanding the folding mechanism of SCNPs is crucial for their application.
• Current methods lack the resolution to detail individual chain folding.

Purpose of the Study:

• To develop and demonstrate a high-resolution method for mapping SCNP folding.
• To provide detailed mechanistic insights into polymer chain collapse.
• To differentiate between various folding mechanisms at the single-chain level.

Main Methods:

• High-resolution electrospray ionization mass spectrometry (ESI MS) coupled with size exclusion chromatography.
• Utilizing a p(MMA-stat-GMA) polymer system collapsed by B(C6F5)3 catalyst.
• Analyzing characteristic mass changes to image polymer chain collapse.

Main Results:

• Successfully imaged the folding of polymeric chains into SCNPs for the first time.
• Provided detailed mechanistic information on the SCNP folding process.
• Differentiated between two distinct mechanistic modes of chain collapse for individual chains.

Conclusions:

• ESI MS coupled with SEC is a powerful tool for studying SCNP formation.
• The developed method offers unprecedented detail into polymer folding mechanisms.
• This approach enables precise characterization of SCNP structures and folding pathways.