Studies On The Drug-loaded Property And In Vivo Distribution Of Galactosylated Fatty Acyl Chitosan Polymeric Micelles

In this paper, blood compatibility of fatty acyl chitosan (F-CS) andgalactosylated fatty acyl chitosan (GF-CS) with different chitosan molecular weight,fatty acyl groups and chitosan/acyl chloride ratio was evaluated to select appropriategalactosylated fatty acyl chitosan as carrier material of polymeric micelles. Theresults showed that the blood compatibility of GF-CS were better than F-CS;palmitoyl chitosan derivatives were better than lauroyl chitosan derivatives; chitosanderivatives prepared with chitosan/chloride mole ratio of1:3were better than those of1:5. The best blood compatibility were shown as follows: GP-CS prepared bychitosan with molecular weight of150000and chitosan/chloride mole ratio of1:17or1:18; GF-CS prepared by chitosan with molecular weight of30000andchitosan/chloride mole ratio of1:3; GF-CS prepared by chitosan with molecularweight of5000and chitosan/chloride mole ratio of1:3.Using Hydroxycamptothecine (HCPT) and Curcumin (Cur) as model drug,drug-loaded polymeric micelles were prepared by dialysis method oremulsifying-solvent evaporation technique respectively according to the solubility ofGF-CS. And the influence of polymer structure parameters (chitosan molecule weight,aliphatic chain length, chitosan/chloride mole ration) on drug loadings andencapsulation efficiency was investigated. In the condition of higher molecule weightchitosan (Mw=150000or30000) used, the higher the chitosan/chloride mole ratio, the greater the drug loading property. The encapsulation efficiency of HCPT and Curloaded GF-CS micelles with chitosan molecular weight of30000andchitosan/chloride mole ratio of1:3reached59.6%and70.1%respectively. In thecondition of lower molecule weight chitosan (Mw=5000) used, the lower thechitosan/chloride mole ratio, the greater the drug loading property. The encapsulationefficiency of HCPT and Cur loaded GF-CS micelles with chitosan molecular weightof5000and chitosan/chloride mole ratio of1:5reached55.8%and70.4%respectively.When chitosan/chloride mole ratio was the same, the longer the aliphatic chain length,the better the drug loading property. Using galactosylated palmitoyl chitosan (GP-CS)prepared with chitosan molecule weight of150000and chitosan/chloride mole ratioof1:18as carrier material, Cur-loaded GP-CS micelles (Cur/GP-CS) were preparedby emulsifying-solvent evaporation technique. The optimal formulation and processwere as follows: the ratio of drug to carrier material was1:15, the ratio of oil phase towater phase was1:7, and the ultrasonic time was30minutes. The drug loading andencapsulation efficiency of Cur/GP-CS were9.1%and96.3%respectively. TheCur/GP-CS were uniform and spherical, with average particle size of179.7nm andzeta potential of76.46mV.HPLC method was used to determine the drug concentrations in the tissues andorgans to investigate the in vivo distribution of HCPT-loaded GP-CS micelles(HCPT/GP-CS) and Cur-loaded GP-CS micelles (Cur/GP-CS) in mice. The resultsshowed that HCPT/GP-CS stayed a relatively longer time in mice, compared withHCPT injection and HCPT/P-CS. Similarly, Cur/GP-CS also stayed a relatively longertime in mice, compared with Cur/P-CS. These indicated that both HCPT/GP-CS andCur/GP-CS had sustained-release effect. Compared with other organs, HCPT/P-CSand Cur/P-CS mainly concentrated in the lung, HCPT/GP-CS and Cur/GP-CS mainlyconcentrated in the liver, followed by the lung. It indicated that HCPT/P-CS andCur/P-CS had passive target effect on the lung, HCPT/GP-CS and Cur/GP-CS hadactive targeting effect on the liver and could reduce the side effect on other tissues.These confirmed that GP-CS polymeric micelle was an appropriate drug carrier for the targeting therapy of liver cancer.MTT method was applied to observe the inhibition effect of HCPT/GP-CS andCur/GP-CS on human liver Bel-7402cells. The results showed that both drug-loadedpolymeric micelles and drugs revealed inhibition effect on Bel-7402cells. Theinhibition rate of HCPT/GP-CS and Cur/GP-CS was higher than that of HCPT/P-CSand Cur/P-CS, and increased with the increase of drug concentration. Compared withthe drug, HCPT/GP-CS and Cur/GP-CS revealed certain sustained-release effect. In this part, a serials of PLGA-PEI amphiphilic block copolymers weresynthetized by terminal carboxyl (lactic acid, glycolic acid) copolymer（PLGA-COOH） and linear polyethyleneimine with different molecular weight(1800, PEI1.8KD;20000, PEI20KD). The produced block copolymers were characterizedby FT-IR、1H-NMR and clinical aggregation concentration (CAC). Polymersomeswere prepared by direct dissolution method with PLGA-PEI as the carriermaterials.The influence of PEI molecular weight, reaction time and the PLGA/PEImole ratio on particle size, zeta potential and CAC of polymersomes wereinvestigated in order to select the appropriate conditions for the preparation ofpolymersomes. The results showed that PLGA-PEI polymersomes with uniform size,minimum particle size (114.7nm) and highest zeta potential (50.24mv) were preparedunder the following condition: PEI molecular weight20KD, reaction time2h andPLGA/PEI mole ratio of1:1.