The preparation and characterization of lactone form of 10-hydroxycamptothecin-layered double hydroxide nanohybrids

• The lactone form of hydroxycamptothecine intercalated LDHs nanohybrids was prepared.
• The nanohybrids have high drug loading and obvious controlled release effect.
• The dispersity of nanohybrids was obviously improved than which prepared in a beaker.
• The nanohybrids showed high biological activity as the drug dissolved in DMSO.

10-Hydroxycamptothecin (HCPT) as a hydrophobic anticancer drug brings many challenges in the clinical applications due to its poor water solubility and its facile structure transformation to inactive structure. In this work, the lactone form of HCPT–LDH nanohybrids with high drug loading was prepared by a two-step method. Firstly, the carboxylate form of HCPT-intercalated LDH was prepared by a coprecipitation method using a microchannel reactor. Secondly, dilute acetic acid was added into the as-precipitates to perform a structure recovery of HCPT in the nanohybrids from carboxylate form to bioactive lactone form because the lactone–carboxylate equilibrium of HCPT is reversible and pH-dependent. The dispersity of HCPT–LDH nanohybrids was obviously improved as compared with particles prepared by conventional method, and the average particle size increased with the drug loading. It was found that the content of HCPT in the nanohybrids with bioactive lactone form reached 95% after treated with acetic acid. For cancer cells, the lactone form of HCPT–LDH was found to be significantly more potent than raw HCPT, and it provided an important foundation for the development and application of nanohybrid delivery system.