Studies Of Vinblastine Imprinted Nano-polymers And Nanoparticles

Nano drug-carrier system is an effective way to overcome the barrier of chemotherapeutic agents, improve the selectivity of drugs to tumors and reduce the aggregation in non-target site.Molecular imprinted polymers (MIPs) are new polymer materials which has a selective recognition to target molecule (template). As the structure of the imprinted cavities matches stereochemically with the template, MIPs have already been used in several areas, such as in analytical chemistry, separation and enzyme catalysts.Recent studies have found that MIPs have excellent performance as drug carrier, such as good stability, resistant to enzyme’s degradation, tolerance of different pH environment, biocompatible and biodegradable, safe, non-toxic. Some foreign research teams have begun to apply MIPs in drug delivery systems.1. ObjectivesIn view of the excellent performance of MIPs in drug delivery system, a new kind of naoo drug-carrier based on MIPs was studied using Vinblastine (VLB) as the template. VLB imprinted nano-polymer (MINP) was synthesized which possessed release and target function and applied for the delivery Catharanthus alkaloid drugs. 2. Contents2.1 To synthesize MINP, optimize the process parameters, character the structure and evaluate the performance of MINP.2.2 To prepare nanoparticles (VLB-MINP) by encapsulating VLB with MINP, investigate the release behavior in vitro, and observe the distribution in rat tissues after tail iv VLB-MINP and VLB injection.3. Methods3.1 Preparation of MINP(1) To Prepare MIP by precipitation polymerization, monodisperse polymerization and bulk polymerization, compare the adsorption amount of the three MIPs to VLB, and determine the synthesis method. The interaction of VLB with MAA was investigated by UV spectra.(2) To optimize the factors influenced the synthesis of MINP with uniform design evaluated by drug loading and encapsulation efficiency.3.2 Characterization and evaluation of MINP(1) To characterize the structure of MINP by scanning electron microscopy (SEM) and particle size analysis instrument.(2) To evaluate the selectivity to VLB of MINP by adsorption and SPE experiments compared with NINP.3.3 Behavior of VLB-MINP release in vitro(1) To prepare VLB-MINP by adsorption method, and investigate the influence of adsorption time and VLB concentration on the drug loading and encapsulation efficiency.(2) To establish the determination method of VLB in the release medium (PBS, pH 7.4). (3) To observe the release behavior of VLB-MINP in PBS.3.4 Distribution of VLB-MINP in rat tissues(1) To establish methods for determining VLB contents in serum and different tissues.(2) To determine the concentration of VLB in serum and different tissues in rats after tail iv VLB-MINP and VLB injection, and evaluate the target function by DTI and DSI.4. Results4.1 Preparation of MINP(1) The adsorption amount of MIP synthesized by precipitation polymerization, bulk polymerization and monodisperse polymerization was 92.5μmol/g,82μmol/g and 72μmol/g respectively. The precipitation polymerization was applied to synthesis MINP since the MINP prepared by this method had small size, large surface area, and good adsorption capacity.(2) The absorbance of VLB at 269nm decreased with adding MAA gradually to VLB solution with constant concentration. The results indicated that that the pre-assembled complex was formed between the template molecule and functional monomer.(3) The optimization parameters by uniform design experiment was as follow, template 0.1mmol, MAA 0.756mmol, TRIM 0.224mmol, acetonitrile 40ml and reaction temperature 60℃. The encapsulation efficiency and drug loading of MINP synthesized under the optimal conditions was 8.72% and 83.25% respectively.4.2 Characterization and evaluation of MINP(1) MINP was microspheres with smooth surface, and the particle size was 300～450nm.(2) The adsorption capacity of MINP to VLB was higher than that of NINP which deduced that MINP had specific adsorption to VLB. There were two kinds of binding sites on MINP, one was high affinity (specific binding sites) and the other was low affinity (nonspecific binding sites) by Scatchard analysis.(3) The adsorption interaction of VLB on SPE cartridge packed with MINP were both specific and non-specific, and the former was mainly destroyed by polarity protic solvents.4.3 Behavior of VLB-MINP in vitro release(1) In the range of 0.36μg/ml～2.52μg/ml of VLB concentration, the liner was good (r= 0.9983). VLB was stable in the release medium for 9 days.(2) When VLB concentration was 1.25 mmol/1 and adsorption time was 4h, the drug loading and encapsulation efficiency of MINP were largest,83.25% and 8.72% respectively.(3) The cumulative release rate of VLB-MINP increased slowly in 9 days. No significant drug burst release was observed. The time reached the cumulative release rate of 50% was 120h and 70% of VLB was released in 216h. The release behavior of VLB-MINP was fit with the first order kinetic equation.4.4 Distribution of VLB-MINP in rat tissues(1) The established method for determining the VLB amount in serum and tissues by HPLC met the requirements of biological sample determination.(2) The concentration of VLB in rat tissues increased after administration VLB-MINP compared with VLB injection, which the increase was significant in liver tissue.(3) DSI of VLB-MINP in liver was highest, followed by kidney, heart, lung, spleen, and DSI of VLB injection group was in turn heart, kidney, liver, lung, and spleen. DSI of VLB-MINP in liver tissue was higher than that of ordinary VLB injection, which indicated that VLB-MINP had higher selectivity to liver. (4) DTI of VLB-MINP in liver was the largest, followed by blood, lung, kidney, spleen, heart. The results also demonstrated the target function to liver of VLB-MINP.5. Conclusions5.1 The optimal conditions of MINP prepared by precipitation polymerization were established by uniform design experiments. The obtained MINP were smooth and had good dispersion. The size was 300-450nm, and the encapsulation, drug loading was 8.72% and 83.25% respectively.5.2 MINP has strong adsorption to template VLB. The adsorption included high affinity (specific binding) and low affinity (non-specific binding) sites.5.3 The release of VLB-MINP in PBS was slow and even, and no burst releasing was observed.70% of VLB was released in 216h. The release behavior of VLB-MINP was fit with the first order kinetic equation.5.4 Compared with ordinary VLB injection, the concentration of VLB in rat tissues were increased, which was obvious significantly in liver tissue. VLB-MINP was liver targeting to some extent.