Related Experiment Video
Updated: May 5, 2026

Visualizing Diffusional Dynamics of Gold Nanorods on Cell Membrane using Single Nanoparticle Darkfield Microscopy
Published on: March 5, 2021
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.
Abstract:
Stimuli-responsive drug delivery systems have expanded the diversity of potential cargos by protecting payloads, extending circulation, and controlling payload release. However, quantitative characterization methods that accurately describe these complex systems are needed to accelerate their translation to the clinic. To this extent, degradable, thermoresponsive polyesters were developed through the ring-opening copolymerization of maleic anhydride and an oligo(ethylene glycol)-functionalized epoxide. The resulting polymers possess a lower critical solution temperature such that they are soluble in aqueous solutions at low temperatures (4-7 °C) but assemble into particles above room temperature (25 °C). The particle size and morphology were tunable through the selection of polymer initiator, forming nanoparticle (ca. 162 nm) and microparticle (ca. 1.85 μm) assemblies using macromolecular polyethylene glycol and small molecule propargyl alcohol initiators, respectively. Diffusion-ordered NMR spectroscopy (DOSY) was used over a range of temperatures to develop molecular weight calibrations using certified poly(ethylene glycol) standards. DOSY was able to monitor the dynamic self-assembly behavior of the thermoresponsive polymers in aqueous solutions, and through distinct diffusion constant shifts, quantify the aggregation number of particle intermediates within the nano- and microparticles.
More Related Videos
08:17Probing Structural and Dynamic Properties of Trafficking Subcellular Nanostructures by Spatiotemporal Fluctuation Spectroscopy
Published on: August 16, 2021
08:48High-Resolution Neutron Spectroscopy to Study Picosecond-Nanosecond Dynamics of Proteins and Hydration Water
Published on: April 28, 2022
Related Concept Videos
¹H NMR: Complex Splitting
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
NMR Spectroscopy: Spin–Spin Coupling
Applications Of NMR In Biology
Other Nuclides: 31P, 19F, 15N NMR
While fluorine-19 and phosphorous-31 have high natural abundances (100%) and positive gyromagnetic ratios, nitrogen-15 has a low natural abundance and a negative gyromagnetic ratio. However, nitrogen-15 is still preferred over nitrogen-14 (which has a...