Pore size distribution of bioresorbable films using a 3-D diffusion NMR method

Area of Science:

• Biomaterials Science
• Materials Characterization
• Medical Imaging

Background:

• Pore size distribution (PSD) is critical for biomaterial performance, influencing biocompatibility, longevity, and drug release.
• Scanning electron microscopy (SEM) is a common but invasive method for PSD analysis, limited by sample preparation and user-dependent field-of-view selection.
• SEM analysis is destructive, requires sample fracturing, and analyzes only a small, user-selected portion of the material.

Purpose of the Study:

• To introduce a novel, non-invasive nuclear magnetic resonance (NMR) method for estimating PSD in soft porous materials.
• To present a 3-D diffusion NMR technique as a superior alternative to SEM for PSD analysis.
• To validate the NMR method's efficacy on porous poly(lactic-co-glycolic acid) (PLGA) films.

Main Methods:

• Utilized a non-invasive, 3-D diffusion nuclear magnetic resonance (NMR) technique.
• Applied the NMR method to four porous 50/50 poly(dl-lactic-co-glycolic acid) (PLGA) bioresorbable films with varying porosities.
• Created porous PLGA films using the freeze-drying of inverted emulsions technique.

Main Results:

• The proposed NMR method provides non-destructive PSD estimation, analyzing the entire specimen volume.
• NMR analysis is independent of magnification factors and user-selected fields of view, unlike SEM.
• Both SEM and NMR yielded comparable PSD results for smaller pores (1-25μm), with NMR additionally characterizing larger pores (25-50μm).

Conclusions:

• The novel NMR method effectively addresses the limitations of SEM for PSD analysis in soft porous biomaterials.
• NMR offers a non-destructive, comprehensive, and user-independent approach to characterizing material microstructure.
• The technique's non-ionizing nature suggests potential preclinical and clinical applications for biomaterial assessment.