Preparation Of Multifunctional Drug Carriers And Its Characterization

In this thesis, PEG5000 and PLA were synthesis biodegradable material mPEG5000-PLA by the method of removing the azeotropic water. As the material, we used mPEG-PLA, PLA to self-assemble nano micelle via nanometer precipitation.We could change the methods of synthesis to determine the micelles of good properties.In the process of preparation, we could change the solvent, concentration and block ratio for controlling the stability of micelles. We would list the research results and characterization:1. Micelle synthesis and optimization: We obtained three structures of micelles: two block micelles mPEG – PLA, two-step mixed micelles, one –step mixed micelles. The size of two block micelles mPEG – PLA is 70-85 nm, the two-step mixed micelles is 65-70 nm and the one –step mixed micelles is 55-65 nm. From the particle size dispersity, two block micelles is the widest and the one –step mixed micelles is the narrowest. Therefore, the one –step mixed one were the ideal micelles.2. Research the effect of solvent in detail: In the research, we used DMF, THF, acetone, ethanol and methanol. And in these solvent, the solubility of acetone, ethanol and methanol is poor. As DMF and THF have good solubility, so they could construct micelles. When DMF was regarded as solvent, the size was 30-75 nm, and THF's was 50-80 nm. By comparison, DMF was the most suitable solvent.3. Research the effect of concentration in detail: We designed the concentration of 1 mg/mL?2 mg/mL?4 mg/mL?6 mg/mL?8 mg/mL?10 mg/mL.In the characterization, the concentration of 1mg/mL?2mg/L?4mg/mL, the size were between 80 nm and 100 nm. When it were 6mg/mL?8 mg/mL?10mg/mL, it were beyond 100 nm. From the point of size dispersity, the 4mg/mL was the most narrowest. Finally, 4mg/mL was the most appropriate concentration.4. Research the effect of block ratio(PLA/mPEG-PLA)in detail:We remained the concentration of PLA to be 4mg/mL and adjust the mPEG-PLA. When the ratio were 2:1?1:1?2:3, the size were 45-100 nm. And it was 1:3, the size was beyond 100 nm, so the structure was disintegrated and distribution irregularly. In characterization, the ratio was 1:1, namely, the concentration were 4mg/mL was the best.5. Research the effect of stability in detail: We simulated physical conditions, such as NaCl salt solution, sodium dodecyl sulfate(SDS) and bovine serum albumin(BSA) solution for the period of 24 h. The size of NaCl salt solution, the SDS, the SBA was was 28-40 nm, 28-37 nm and 31-41 nm. The one-step mixed micelles were 28-35 nm and the change of particle dispersity was not wide. So the one-step mixed were more stable. Furtherly, we used FRET effect to determine that one- step mixed micelles was the best. Eventually it could embody the rationality and application.