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Published on: August 9, 2022
Quantitative XPS depth profiling of codeine loaded poly(l-lactic acid) films using a coronene ion sputter source
Ali Rafati1, Martyn C Davies, Alexander G Shard
1Laboratory of Biophysics and Surface Analysis, University of Nottingham, School of Pharmacy, Nottingham, NG7 2RD, UK.
Summary
Controlled drug release from polymers is key for medical devices. This study reveals drug depletion from surfaces in polymer films, impacting drug delivery system performance.
Area of Science:
- Materials Science
- Polymer Chemistry
- Surface Science
Background:
- Controlled release of active pharmaceutical ingredients from polymers is critical for drug-eluting stents and other medical devices.
- Understanding drug distribution within polymer matrices is essential for predicting device performance in vitro and in vivo.
Purpose of the Study:
- To investigate the drug distribution in a model drug-loaded polymer system using X-ray photoelectron spectroscopy (XPS) depth profiling.
- To quantitatively analyze atomic concentrations throughout the thickness of poly(l-lactic acid) (PLA) films containing codeine.
Main Methods:
- Fabrication of thin (up to 96 nm) PLA films with codeine using spin-casting on silicon wafers.
- Determination of total film thickness and relative drug loading via ellipsometry and spectroscopic analysis.
- XPS depth profiling utilizing a novel coronene ion sputter source to analyze atomic concentrations as a function of depth.
Main Results:
- XPS depth profiling revealed that codeine was depleted from the surface of the PLA films.
- Analysis indicated segregation of codeine towards the bulk of the polymer films.
- Observed drug distribution differed significantly from a calculated uniform distribution based on bulk loading.
Conclusions:
- The study demonstrates surface depletion of active pharmaceutical ingredients in drug-loaded polymer systems.
- This finding has significant implications for the design and performance of drug delivery devices, particularly concerning initial drug release rates.
