The feasibility of cluster Secondary Ion Mass Spectrometry (SIMS) for depth profiling of drug delivery systems is explored. Behaviors of various biodegradable polymer films under dynamic SF5+ primary ion bombardment was investigated including several films doped with model drugs. The SF5+ depth profiles obtained from these biodegradable polymer films showed very little degradation in secondary ion signal as a function of increasing primary ion dose, and it was discovered that the characteristic ion signals for the polymers remained constant for ion doses up to ~5 x1015 ions/cm2. These results suggest that the polyester structure of the biodegradable polymers studied here allow for a greater ability to depth profile due to ease of main chain scission. Attempts were also made to depth profile through a series of polylactic acid (PLA) films containing varying concentrations of the drug 4-acetamidophenol. The depth profiles obtained form these films show very little degradation in both the 4-acetamidophenol molecular ion and PLA fragment ion signals as a function of increasing SF5+ primary ion dose. Similar results were obtained with theophylline doped PLA films. These results show that in some drug delivery devices, it is possible to monitor the distribution of a drug as a function of depth by using cluster primary ion beams.
Citation: Analytical Chemistry
Issue: No. 11
Pub Type: Journals
Cluster SF<sub>5</sub><sup>+</sup>, controlled release, depth profile, drug delivery, TOF-SIMS