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Updated: Jul 13, 2026
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From Fast Fluorescence Imaging to Molecular Diffusion Law on Live Cell Membranes in a Commercial Microscope
Published on: October 9, 2014
Real time observation of diffusion and bioaffinity binding processes in single polyelectrolyte-coated microcapsules:
Wing Cheung Mak1, Hong Yangzhong, Dieter Trau
1Division of Bioengineering, Faculty of Engineering, National University of Singapore, 7 Engineering Drive 1, Singapore 117574, Singapore.
Colloids and Surfaces. B, Biointerfaces
|August 19, 2007
Summary
Researchers visualized real-time diffusion and bioaffinity binding within microcapsules using fluorescence microscopy. They determined the diffusion coefficient of biotin-fluorescein, finding it comparable to similar molecules.
Area of Science:
- Biomaterials Science
- Chemical Engineering
- Physical Chemistry
Background:
- Microcapsules are versatile structures for encapsulating active compounds.
- Understanding diffusion and binding kinetics within microcapsules is crucial for applications.
- Layer-by-Layer (LbL) self-assembly offers precise control over microcapsule fabrication.
Purpose of the Study:
- To investigate real-time diffusion and bioaffinity binding within single microcapsules.
- To quantify the diffusion coefficient of biotin-fluorescein.
- To develop and validate a model for diffusion processes in microcapsules.
Main Methods:
- Utilizing fluorescence microscopy to visualize dynamic processes in situ.
- Employing biotin-fluorescein as the diffusive species and encapsulated avidin as the binding partner.
- Constructing microcapsules via agarose entrapment of avidin and Layer-by-Layer (LbL) polyelectrolyte coating.
Main Results:
- Observed a time-dependent "ring" of fluorescence advancing towards the microcapsule center.
- Visualized real-time fluorescence build-up indicating avidin-biotin binding.
- Developed a diffusion model that accurately fitted experimental data.
- Determined the diffusion coefficient of biotin-fluorescein to be 3.5x10^-8 cm²/s.
Conclusions:
- Fluorescence microscopy effectively visualizes real-time diffusion and binding within microcapsules.
- The developed model accurately describes diffusion phenomena in these systems.
- The determined diffusion coefficient is consistent with literature values for similar molecules, validating the experimental approach.
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