ABSTRACT
Objective: To prepare a PEOz modified single-walled carbon nanotube delivery system (PEOz-SWCNT) with the anti- tumor drug paclitaxel (PTX) as a model drug (PTX@PEOz-SWCNT) and evaluate its physical and chemical properties, in vitro drug release, biocompatibility, and in vitro antitumor effects. Methods: PEOz-SWCNT was synthesized by chemical coupling method, and the products were characterized by UV-Vis spectroscopy (UV-Vis) and infrared spectroscopy (FTIR). The particle size and Zeta potential of PEOz-SWCNT were measured. The drug-loaded complex PTX@PEOz-SWCNT was prepared and the loading efficiency and encapsulation efficiency were measured. The dialysis method was used for in vitro drug release. The safety of the application of PEOz-SWCNT was evaluated by in vitro hemolysis test. The MTT method was used to evaluate the biocompatibility of the material and the growth inhibition rate of the drug-loaded complex on MCF-7 cells. The uptake of Coumarin-6 (C6)-labeled vector in MCF-7 cells was examined by fluorescence inversion microscope. Results: The average particle size of PEOz-SWCNT was (219.8 ± 2.9) nm and the Zeta potential was (-35.23 ± 0.74) mV. The loading efficiency of PTX@PEOz-SWCNT was (38.19 ± 0.74) %, and the encapsulation efficiency was (94.38 ± 0.94)%. The drug release rate was significantly accelerated at pH 5.0, showing obvious pH responsiveness. There was no obvious hemolysis when the concentration of PEOz-SWCNT was below 0.4 mg/mL. The biocompatibility of PEOz-SWCNT on Hela cells was good, and the PTX@PEOz-SWCNT could significantly enhance the cell growth inhibition rate on MCF-7 cells. The in vitro antitumor activity test results showed that the cell uptake of the C6@PEOz-SWCNT was increased compared to C6@SWCNT. Conclusion: PTX@PEOz-SWCNT drug delivery system is promising in tumor-targeted drug delivery.
ABSTRACT
OBJECTIVE: To prepare small interfering RNA(siRNA) lipid complexes (TPOS-L/siRNA) modified by D-α-tocopheryl poly (2-ethyl-2-oxazoline) succinate (TPOS). METHODS: The conventional siRNA lipid complexes (CLs /siRNA) and PEGylated CLs /siRNA (PEG-L/siRNA) were used as controls. CLs /siRNA was prepared by mixing blank CLs and siRNA directly of equal volume according to the electrostatic interaction of positive and negative charges. The encapsulation efficiency, morphology, stability, in vitro release and cell uptake of TPOS-L/siRNA were investigated. RESULTS: The CLs/siRNA had obvious lipid bilayer structure, the encapsulation efficiency (EE) was (86.68 ± 1.41)%, and the particle size of CLs /siRNA was less than 200 nm. The modification with TPOS or PEG-DSPE had no significant effect on the EE and particle size of CLs /siRNA, which could endow the lipid complexes with good stability. In addtion, TPOS-L/siRNA had good pH-sensitive property, and could respond to slightly acidic environment, which significantly enhanced the cell uptake. CONCLUSION: TPOS can construct good siRNA carrier and increase the stability and pH sensitivity of the nanocarrier.
ABSTRACT
Poly(2-ethyl-2-oxazoline) (PEOz), a hydrophilic long-chain polymer synthesized by living cationic ring-opening isomerization polymerization of 2-ethyl-2-oxazoline, has the characteristics of low toxicity, biocompatibility, flexible chain, and modified expediently. PEOz is a potential substitute of polyethylene glycol (PEG) to render the ability of long-circulation, enhance cellular uptake and endosomal escape behaviors to PEOz modified drug delivery system. In this review, we summarized recent literature for the research progress of physicochemical properties, synthetic methods and the application of PEOz in drug delivery system.
ABSTRACT
Objective:To synthesize poly (2-ethyl-2-oxazoline)-poly(lactic acid) copolymer (PEOz-PLA), prepare pH-sensitive paclitaxel-loaded polymeric micelles, and evaluate the in vitro properties. Methods: The structures of all the synthesized copolymers were confirmed by 1 HNMR and Fourier transform infrared spectroscopy ( FTIR) . The drug-loaded micelles were prepared by a dialysis method. The micelles solution was freeze-dried and the lyoprotectants were screened. The critical micelle concentrations ( CMC) of the copolymers were measured by pyrene fluorescent probe technique. The distribution of particle size was measured by dynamic light scat-tering ( DLS) . The in vitro release behavior of the loaded micelles at different pH conditions was studied by a dialysis method. Re-sults:The CMC of micelles was 25. 63 mg·ml-1 . When 10% polyethylene glycol 4000 was used as the lyoprotectant, the re-solubili-ty of micelles was good and the distribution of particle size was narrow. The drug loading rate of micelles was 8. 12% and the encapsu-lation efficiency was 69. 33%. The average particle size of freeze-dried micelles was 183. 7 nm. The in vitro release of the drug-loaded micelles showed that the drug released slowly at pH 7. 4 and fast at pH 5. 0, which indicated that the change of pH could affect the drug release. Conclusion:The preparation of PEOz-PLA polymer micelles is simple. The particle size, entrapment efficiency and drug loading are controllable. The micelles have a certain sustained-release effect, which provides basis for further pharmacological study and clinical application.
ABSTRACT
OBJECTIVE: To establish the method for determinating the activity of [poly(2-ethyl-2-oxazoline), PEOZ]-modified liposomes encapsulated superoxide dismutase (SOD) mimic (PEOZ-L-SOD). METHODS: PEOZ-L-SOD was prepared by film dispersion method, and the activities of the SOD mimic and PEOZ-L-SOD were determined by NBT-Illumination method. RESULTS: The fitted equation of the inhibition rate curve of the SOD mimic was IR%=33.4211nρ + 49.715 (r2=0.9992) and the IC50 was 1.0086 × 10-3 μmol · L-1; the fitted equation of the inhibition rate curve of PEOZ-L-SOD was IR%=33.5211nρ + 49.671 (r2=0.9991) and the IC50 was 1.0099 × 10-3 μmol · L-1. CONCLUSION: The NBT-Illumination method is simple, reliable, economic and practical, and can be used as an efficient method to determine the activity of SOD mimic liposomes. The experiment proves that the activity of SOD mimic did not change after it was encapsulated in the liposomes.