Keywords: 
• camptothecin /
• nano gel /
• CPT-PPO gel /
• in vitro transdermal permeability

Abstract: Objective To prepare a novel drug delivery system camptothecin loaded nanogel(CPT-PPO gel), and investigate its contents, physical and chemical properties and in vitro transdermal permeability. Methods The solvent evaporation method was utilized to prepare core-shell nano-drug delivery systems(CPT-PLGA-PAMAM, CPT-PP), in which the Poly lactic-co-glycolic acid(PLGA) was used to load camptothecin as the nucleus and the polyamidoamine(PAMAM) G3.0 was wrapped in the surface of PLGA as the shell. Then the oleic acid(OA) was connected to CPT-PP to obtain the surface modified drug delivery system(CPT-PLGA-PAMAM OA, CPT-PPO). HPLC was used to determine the content of camptothecin in nanoparticles, transmission electron microscopy was applied to identify the nanoparticles morphology, and laser analyzer was used to determine the particle size. The hydroxypropyl methylcellulose(HPMC) was added as the base for the preparation of the nanogel(CPT-PPO gel) at last. The Franz-diffusion cell was used to determine the permeation rate of nanogel in vitro. Results The resulting CPT-PPO gel was stable at 4℃, the average particle size was(246.7±5.4) nm and the encapsulation efficiency was up to(78.7±6.9)%. Comparing to the normal gel,(CPT gel), the cumulative penetration amount and the retention amount in the skin of the nanogels(CPT-PPO gel,CPT-PP gel) were significant higher(P<0.01), the retention and cumulative penetration amount of CPT-PPO gel was significant higher than that of CPT-PP gel(P<0.05). Conclusion After modified by OA, CPT-PPO gel can increase the cumulated amount and absorption in skin and can be used as a carrier of CPT in the new formulation for topical treatment of psoriasis.