PH-sensitive Bletilla Striata Polysaccharide Copolymer Micelles And Enhanced Tumour Suppression In Vivo And In Vitro

In recent years,with the continuous emergence of various functional polymer materials,the new drug delivery system had become the development direction of the pharmacy.Environmental sensitive polymer is a new functional polymer material that can perceive physical or chemical stimuli of external environment(such as temperature,pH,ionic strength,etc.),also known as intelligent polymers.Based on the preparation of SA-BSP polymers at the early stage of the research group,we further explored the methods to improve the drug loading and entrapment efficiency of micelles,and investigated whether they had pH sensitivity,and evaluated their anticancer activities in vivo and in vitro.First of all,the SA-BSP copolymers were synthesized by the previous work of the project group,and the fluorescent substance FITC was grafted to SA-BSP to facilitate the investigation of the intracellular uptake of micelles.It was confirmed by IR and NMR.The results show that FITC has been grafted to SA-BSP.A mixed solvent was used to dissolve docetaxel and to prepare loaded-docetaxel micelles.The results showed that the dosage of DTX was increased when chloroform: ethanol =3:1(v/v)was dissolved.The particle size,zeta potential and in vitro release of micelles under different pH were measured.High performance liquid chromatography(HPLC)was used to determine the release of DTX under different pH medium conditions in vitro.The anticancer activity of MCF7 and A549 cells was studied in vitro.The rate of cell uptake and apoptosis was detected by flow cytometry.The result is known that pH had an obvious effect on the release of DTX from DTX-SA-BSP micelles,and after 48 h in pH 5.0,6.0 or 7.4 PBS,DTX release from DTX-SA-BSP micelles was(79.25 ± 1.80)%,(71.64 ± 0.80)% and(68.58 ± 1.70)%,respectively.The release of DTX-SA-BSP copolymer micelles was the fastest at pH 5.The cell viability of DTX-SA-BSP copolymer micelles against MCF-7 and A549 were(40.2 ± 1.43)% and(12.3 ± 4.1)%,respectively,whereas the cell viability of DTX solution were(50.23 ± 2.85)% and(53.4 ± 5.4)%,respectively at 0.5 ?g/mL concentration.The percentage of apoptotic cells after treatment with DTX-SA-BSP copolymer micelles or DTX solution at 0.5 ?g/mL was 73.48 % and 69.64 %,respectively.The results of laser confocal,flow cytometry and high performance liquid chromatography(HPLC)showed that the uptake of DTX-SA-BSP copolymer micellar cells was stronger than that of DTX solution.The tumour growth inhibition rates of DTX-SA-BSP micelles and DTX solution were 59.05 % and 44.29 %,respectively,after 17 days of treatment in BALB/c 4T1 tumour-bearing mice The cytotoxicity of DTX-SA-BSP copolymer micelles in vitro was higher than that of DTX solution.The anticancer targets in the body further confirm that the DTX-SA-BSP copolymer micelles have better anticancer effects.Therefore,SA-BSPs copolymer can be used as a carrier for delivering hydrophobic drugs.