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Observation of Dynamic Aggregation Behavior in Thermoresponsive Micro- and Nanoparticles via Diffusion-Ordered NMR
Anshu Agarwal1, Benjamin G Bobay2, Matthew L Becker1,3,4,5
1Thomas Lord Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, United States.
Journal of the American Chemical Society
|March 7, 2025
Summary
Researchers developed new thermoresponsive polymers for drug delivery. These polymers self-assemble into nanoparticles or microparticles, and diffusion-ordered NMR spectroscopy (DOSY) quantifies their aggregation behavior.
Area of Science:
- Polymer Chemistry
- Materials Science
- Nanotechnology
Background:
- Stimuli-responsive drug delivery systems enhance cargo protection, circulation time, and controlled release.
- Quantitative characterization methods are crucial for translating these complex systems to clinical applications.
Purpose of the Study:
- To develop degradable, thermoresponsive polyesters for drug delivery.
- To characterize the self-assembly behavior and particle formation of these polymers.
- To utilize Diffusion-Ordered NMR Spectroscopy (DOSY) for quantitative analysis.
Main Methods:
- Ring-opening copolymerization of maleic anhydride and oligo(ethylene glycol)-functionalized epoxide.
- Tuning particle size (nano- vs. microparticles) by selecting different polymer initiators.
- Employing Diffusion-Ordered NMR Spectroscopy (DOSY) with poly(ethylene glycol) standards for molecular weight calibration and aggregation number determination.
Main Results:
- Synthesized thermoresponsive polyesters with a lower critical solution temperature (LCST) for tunable self-assembly.
- Achieved nanoparticle (approx. 162 nm) and microparticle (approx. 1.85 μm) formation based on initiator choice.
- DOSY successfully monitored polymer self-assembly and quantified aggregation numbers in aqueous solutions across temperatures.
Conclusions:
- Developed novel thermoresponsive polymers suitable for stimuli-responsive drug delivery.
- Demonstrated the utility of DOSY as a quantitative tool for characterizing polymer self-assembly and aggregation in solution.
- The findings facilitate the advancement of complex drug delivery systems towards clinical use.
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