Assaying the Gel Cell Size through Fluorescence Anisotropy Measurements

Area of Science:

• Physical Chemistry
• Materials Science
• Biophysics

Background:

• Understanding gel microstructure is crucial for various applications.
• Rotational diffusion of molecules within gels is a key indicator of structural constraints.
• Fluorescence anisotropy is a sensitive technique for probing molecular dynamics.

Purpose of the Study:

• To assess the gel structure of dimethyl sulfoxide (DMSO)-MgSO4.
• To determine the limitations of rotational diffusion within gel structural elements.
• To establish the characteristic size of gel cells using fluorescent probes.

Main Methods:

• Studied fluorescence anisotropy changes in luminophores of varying molecular sizes.
• Applied the Levshin-Perrin equation to describe fluorescence anisotropy.
• Investigated the behavior of fluorescent probes within the DMSO-MgSO4 gel environment.

Main Results:

• Small fluorescent probes (<2.1 nm) showed unrestricted rotational diffusion, fitting the Levshin-Perrin equation.
• Larger probes (>2.1 nm) exhibited stopped rotational diffusion, indicating entrapment within gel cells.
• The characteristic size of the DMSO-MgSO4 gel cell was determined to be 2.3 nm.

Conclusions:

• The gel structure imposes significant constraints on molecular motion for larger molecules.
• A modified Levshin-Perrin equation was developed, incorporating gel cell statistical parameters.
• This study provides insights into the nanoscale architecture and molecular confinement within DMSO-MgSO4 gels.