Dynamic SIMS utilizing SF5+ polyatomic primary ion beams for drug delivery applications

The behavior of various biodegradable polymer films (e.g. polylactic acid, polyglycolic, acid and polycaprolactone) as well as some model drugs (theophylline and 4-acetamidophenol) under dynamic SF5+ primary ion bombardment is explored. A series of polylactic acid films containing varying concentrations of 4-acetamidophenol are also analyzed under similar conditions. The resultant molecular depth profiles obtained from these polymer films doped with drug show very little degradation in molecular signal as a function of SF5+ primary ion dose, and it was found that the molecular ion signals of both polymer and drug remained constant for ion doses up to similar to5 x 10(15) ions/cm. In addition, the polymer film/Si interface was well defined which may imply that sputter-induced topography formation was not a significant limitation. These results suggest that the structure of the biodegradable polymers studied here which all have the common main chain structural unit, R-CO-O-R, allows for a greater ability to depth profile due to ease of bond cleavage. Most importantly, however, these results indicate that in these particular polymer systems, the distribution of the drug as a function of depth can be monitored. (C) 2004 Elsevier B.V. All rights reserved.