Environmental Digital Pulsed Force Mode AFM in Biomedical Coatings Research

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We report ongoing methodological developments using Digital Pulsed Force Mode AFM of model coatings containing the drug dexamethasone dispersed in polylactide (biodegradable), poly(butylmethacrylate) (PBMA), and PBMA/poly(laurel methacrylate) (PLMA) blends. Studies include (1) multi-technique analyses, understanding D-PFM AFM results in conjunction with electron, light and confocal-Raman microscopy; (2) comparing drug-polymer segregation in microsprayed and spin-cast coatings, to examine kinetic differences in coating application (i.e., of solvent evaporation); (3) aqueous AFM of drug elution, in conjunction with conventional drug-release profiles; and (4) elevated temperature and humidity as “knobs” to yield material contrast and mobilize drug. Corresponding results include (1) the identification of SEM e-beam modifications, and distinctly different surface vs. bulk (AFM vs. Raman) drug segregation, important to burst vs. longer term release; (2) dramatic differences in drug segregation in sprayed vs. spin-cast coatings; (3) rapid formation of nanoscale surface holes during burst phase, and subsurface drug aggregation then release over much longer times; (4) both humidity- and temperature-induced drug crystallization in the vicinity of rubbery polymer domains in which the drug is less miscible. We conclude that environmental D-PFM AFM is an extraordinarily powerful tool to assess myriad issues within drug-eluting coatings research and development.

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Journal: TechConnect Briefs
Volume: 1, Nanotechnology 2009: Fabrication, Particles, Characterization, MEMS, Electronics and Photonics
Published: May 3, 2009
Pages: 277 - 280
Industry sector: Advanced Materials & Manufacturing
Topic: Materials Characterization & Imaging
ISBN: 978-1-4398-1782-7