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SIMS Depth Profiling of Polymer Blends With Protein Based Drugs



Christine M. Mahoney, J Yu, Albert J. Fahey, J Gardella


The use of SF5+ cluster ions for depth profiling has been successful for polymer-drug mixtures and polymer blends. This study reports results of the surface and in-depth characterization of two component blend films of poly(L-lactic acid) (PLLA) and Pluronic surfactant [poly(ethylene oxide) (A) poly(propylene oxide) (B) ABA block copolymer]. Angle dependant X-ray photoelectron spectroscopy (XPS) and Time-of-flight secondary ion mass spectrometer (ToF-SIMS) depth profiling were used for monitoring the surfactant's surface concentration at different sampling depths. We found a critical saturation concentration of the surfactant, a depletion region beneath the topmost surfactant enriched zone, and the existence of the surfactant's segregation in the whole film with different intensities. A key comparison between the results from different methods includes the depth scales of the distribution of components. Results from angle dependent XPS and ToF-SIMS depth profiling are compared. With respect to the polymer blend results, we conclude that the surfactant's surface segregation increases and then stays stable when increasing its bulk concentration. These results suggest that the selection of the surfactant bulk concentration of the thin film matrices for drugs/proteins delivery should achieve a relatively homogeneous distribution of stabilizer/protein in the PLLA matrix. ToF-SIMS depth profile analysis of three component blends of biodegradable polymers, surfactants and proteins are reported. PLLA based membranes loaded with insulin are stabilized with surfactants to retain activity of the protein for drug delivery Imaging ToF-SIMS results show the spatial distribution of surfactant/protein mixtures, and these data are reported also as depth profiles.
Applied Surface Science


AD-XPS, depth profiling, drug delivery, PLLA, pluronic, ToF-SIMS


Mahoney, C. , Yu, J. , Fahey, A. and Gardella, J. (2006), SIMS Depth Profiling of Polymer Blends With Protein Based Drugs, Applied Surface Science (Accessed April 15, 2024)
Created July 1, 2006, Updated February 19, 2017