Tumor-Targeted Fluorouracil Dendrimer Nanoparticles

Cancer is the most common disease and the frequently encountered disease to threaten human healthy. pH responsive drug delivery directly to the tumor position has already become the hot spot of research. pH responsive block copolymer and pH responsive dendrimer nanocarrier was designed in this article and 5-fluorouracil was selected as the model drug to prepare 5-fluorouracil nanoparticles, Characteristics and regularities of 5-FU nanoparticles in vitro and in vivo were determined. The main contents were described in details as follows.1. Synthesis of pH responsive dendrimer nanocarrierFirst,was synthesized via atom transfer radical polymerization(ATRP) by successive polymerization of 2-(diethylamino)ethyl methacrylate (DEA) using a mPEG-based ATRP macroinitiator. Reacting the obtained mPEG2000-pDEA block copolymer. Nitrine modification.Then, polyamidoamine (PAMAM) dendrimers of the third generation were synthesized with the diversity method. Alkynyl modification.As a result, Using Click chemistry obtained Polyethylene glycol methyl ether2000 (mPEG2000) and poly(N,N-diethylaminoethyl mathacrylate) (pDEA) and PAMAM dendrimer mPEG2000-pDEA-PAMAM (PDP).2. Characteristics of mPEG2000-pDEA block copolymer and mPEG2000-pDEA-PAMAM (PDP)The microstructure of PAMAM and PDP, such as particle size,charge and Langmuir was determined. The apparent particle size of PD and PDP was both <150 nm and the PDP surface Zeta potential was 5.8mV, respectively. The dynamic light scattering showed that as the surface of PD and PDP had pH sensitivity.3. Preparation and characteristics of 5-FU nanoparticles5-FU nanoparticles(5-FU-PDP)were prepared and the techniques and formulation screening was made. The formulation was optimized with the encapsulation efficiency and drug loading as the evaluation index. pH sensitivity of 5-FU-PDP was also proved. The results showed that the apparent particle size of 5-FU-PDP was about 92 nm and the surface Zeta potential was 5.8 mV. 4. Physical stability of 5-FU-PDPContent of 5-FU didn't decrease at -4℃for one month. Nanoparticles of high concentration could redisperse easily and the content of 5-FU did not change obviously.5. In vitro release Profiles of 5-FU-PDPIn vitro release experiments of 5-FU and 5-FU-PDP was carried out with the dialysis method to simulatie the environment in vivo. 5-FU released from the PDP were obtained by a dissolution test in different phosphate buffer solution (pH6.5 and pH 7.4 PBS release medium, respectively). The results demonstrated that the release behaviors of 5-FU in PBS ( pH6.5, pH7.4) in vitro were uniform fundamentally. However, the release behaviors of 5-FU-NP in weak acid environment (pH6.5) released fast and slowly in the neutral environment. It certificated that 5-FU-PDP had good pH sensibility.6. Pharmacokinetics and tissue distribution of 5-FU-PDPAfte iv administration to normal Kunming mice, 5-FU-PDP were eliminated quickly from blood circulation to major tissue (liver, kidney, spleen). The distribution t1/2 and elimination t1/2 were 2.686 and 21.712 min, respectively. 5-FU-PDP was eliminated in vivo within 8h. The Kunming mice models with Hepatoma (H22) were established. After iv administration to tumor-beared Kunming mice, 5-FU nanoparticles were distributed quickly from blood circulation to tumor, distribution t1/2 and elimination t1/2 in mice were 4.01 and 2760619.47min, respectively. The content of 5-FU in tuomr is the most than other tissues (liver, kidney, heart, etc.).It demonstrated that 5-FU-PDP had obvious tumor targeting.7. Pharmacodynamics experiments of 5-FU nanoparticles in Hepatoma (H22) tumor–bearing Kunming mice.After iv administration of Hepatoma (H22) tumor to Kunming mice for 9 days successively and the evaluation index was the body weight and tumor volume. The results showed that the blank carrier group and the negative control group had no difference. It demonstrated that PDP carriers group didn't have toxicity. The tumor inhibition ratio of 5-FU-PDP and 5-FU was 91% and 74%, respectively (p<0.01). It proved that 5-FU-PDP decreased the toxicity of 5-FU, and increased the tumor targeting. Moreover, therapeutic effects was elevated. pH responsive nanocarrier(Polyethylene glycol methyl ether2000 (mPEG2000) and poly(N,N-diethylaminoethyl mathacrylate) (pDEA) and PAMAM dendrimer mPEG2000-pDEA-PAMAM (PDP)) was synthesized and the antitumor drug -5-FU was encapsulated in this article. 5-FU nanoparticles were prepared of nano-size, pH responsive and long circulation. It demonstrated that this dosage form could load drug with high efficiency, decrease toxicity of 5-FU and target to tumor directly.