Steady-state fluorescence study on release of camptothecin from agar hydrogel

The slow drug release processes from agar hydrogel were studied by steady-state fluorescence (SSF) measurement. An anticancer drug, camptothecin (CPT), was used as the release drug and the fluorescence probe for the real-time monitoring of the release processes by measuring the fluorescence intensity of the probe. The release kinetics of CPT at different temperatures was investigated. The Fickian diffusion model was adopted to fit the results and a good linear relationship could be observed between the logarithmic release fraction and the releasing time. The diffusion coefficients (D) at these conditions were thus obtained from the slopes of the fitting curves. By plotting D against temperature, the diffusion coefficient of CPT was found to obey the Arrhenius relation and the activation energy was then obtained to be 70.6 kJ mol ^-1.