Morphology, Loadability, and Releasing Profiles of CalliSpheres Microspheres in Delivering Oxaliplatin: An In Vitro Study

Objectives: This study aimed to explore the morphology, loadability, and releasing profiles of CalliSpheres microspheres in delivering oxaliplatin. Methods: Varied amount (20, 40, 60, and 80 mg oxaliplatin) and concentration (1.25, 2.5, 5.0 mg/mL oxaliplatin) of oxaliplatin were mixed with CalliSpheres microspheres with 3 sizes (50-150 μm, 100-300 μm, and 300-500 μm) to measure the loadability. Of all, 20 mg oxaliplatin-loaded CalliSpheres microspheres with 3 sizes was prepared to measure the releasing profiles, meanwhile, fetal bovine serum was added to determine the effect of serum on oxaliplatin releasing. The morphology and size distribution of CalliSpheres microspheres with 3 sizes before and after 20 mg oxaliplatin loading were detected. Results: Oxaliplatin amount was negatively correlated with loading efficiency with highest loadability in 20 mg oxaliplatin group (maximum 40% in 50-100 µm CalliSpheres microspheres, 52% in 100-300 µm CalliSpheres microspheres, and 52% in 300-500 µm CalliSpheres microspheres), while oxaliplatin concentration was positively associated with loading efficiency. Similar drug-releasing profiles were observed among oxaliplatin-loaded CalliSpheres microspheres with 3 sizes, and a rapid drug release was discovered in CalliSpheres microspheres with 3 sizes as well. We also found that fetal bovine serum did not affect the drug-releasing profiles of oxaliplatin-loaded CalliSpheres microspheres. In addition, CalliSpheres microspheres was modified a little to ellipse shape and less smooth after oxaliplatin loading, and it was enlarged to some extent. Conclusion: This study discloses drug loadability, releasing profiles, and morphology change of CalliSpheres microspheres for delivering oxaliplatin, which provides potential evidences for application of oxaliplatin-loaded drug-eluting beads in clinical practice.