Resolving the internal morphology of core-shell microgels with super-resolution fluorescence microscopy

Area of Science:

• Colloid and Polymer Science
• Soft Matter Physics
• Advanced Microscopy Techniques

Background:

• Smart core-shell microgels are advanced colloidal materials with tunable properties.
• Understanding their internal morphology is crucial for optimizing their performance in various applications.
• Current imaging techniques often lack the resolution or perturb the delicate network structure.

Purpose of the Study:

• To investigate the internal morphology of smart core-shell microgels.
• To demonstrate the utility of super-resolution fluorescence microscopy for soft colloidal systems.
• To analyze structural changes during microgel synthesis without chemical labeling.

Main Methods:

• Utilized a combination of 3D single molecule localization microscopy (3D-SMLM) and structured illumination microscopy (3D-SIM).
• Employed freely diffusing fluorescent dyes for imaging, avoiding chemical labeling of the microgel network.
• Applied these techniques to analyze the internal structure of core-shell microgels with high precision.

Main Results:

• The core-forming seed particles undergo significant structural alterations during the shell synthesis step.
• A highly increased dye localization density was observed in the core region after shell formation.
• The super-resolution approach provided unprecedented detail on the microgel internal morphology.

Conclusions:

• Super-resolution fluorescence microscopy is a powerful, non-perturbing tool for studying soft colloidal systems.
• The synthesis process for core-shell microgels leads to substantial changes in the core's internal structure.
• This methodology opens new avenues for characterizing complex soft materials.