Diffusion dynamics of small molecules from mesoporous silicon films by real-time optical interferometry

Area of Science:

• Materials Science
• Physical Chemistry
• Biomedical Engineering

Background:

• Mesoporous silicon (PSi) is a promising material for drug delivery due to its tunable porosity.
• Understanding analyte diffusion dynamics within PSi is crucial for optimizing drug release profiles.
• Current methods for characterizing diffusion in PSi can be limited in their temporal and spatial resolution.

Purpose of the Study:

• To rigorously characterize the time-dependent diffusion dynamics of small molecules from mesoporous silicon films.
• To determine the diffusion coefficients of sucrose as a model analyte using a novel measurement and modeling approach.
• To investigate the influence of PSi film properties (pore size, thickness) on diffusion characteristics.

Main Methods:

• Utilized time-dependent laser reflectometry for real-time monitoring of analyte release.
• Employed a one-dimensional Fickian diffusion flow model incorporating spatially and temporally dependent solute concentration.
• Calculated diffusion coefficients for sucrose (340 Da) exiting from PSi films with varying pore sizes (10-30 nm) and thicknesses (300-900 nm).

Main Results:

• Demonstrated that diffusion coefficients for sucrose can be tuned between approximately 100 and 550 μm²/s.
• Established a clear dependence of diffusion properties on both PSi pore size and film thickness.
• Successfully applied the measurement and modeling approach to characterize diffusion in PSi systems.

Conclusions:

• Laser reflectometry coupled with Fickian diffusion modeling provides a robust method for characterizing analyte diffusion in PSi.
• PSi film characteristics offer a means to precisely control and tune small molecule diffusion for targeted applications.
• The developed approach can be extended to study molecules with complex interactions within PSi, including those that corrode the material.