Preparation Of PH/GSH Reduction Responsive Click Particles For Drug Loading And Release

Malignant tumors are seriously endangering human health.The use of free chemotherapy drugs will produce greater toxic and side effects,and the treatment efficiency is lower.Stimuli-responsive polymer microspheres can be used as drug carriers to sense changes in the surrounding environment,such as pH,GSH,temperature,etc.,using the differences between tumor and normal tissue environments,can target controlled-release drugs,increase drug stability,and improve drug biocompatibility.Generally,drug loading polymer microspheres are prepared by swelling centrifugation、dialysis and solvent evaporation method,but polymer materials need to be prepared in advance,and there are many steps.Solvent evaporation method often uses toxic solvents,which is harmful to the human body.Adding the drug directly to the heterogeneous polymerization system can reduce the steps and increase the drug encapsulation efficiency.However,the mechanism of heterogeneous polymerization is radical chain growth polymerization and step condensation polymerization,but the required high temperature or light and heat conditions will cause the denaturation of the drug.Click chemistry has many advantages,such as fast reaction rate,simple reaction,mild reaction conditions,water and oxygen resistantit,product stability and easy to separate.It can be used to prepare drug loading polymer microspheres.Our research group used click dispersion polymerization to prepare polymer microspheres with monodispersity,controllable morphology and particle size at room temperature in one pot.They were used in Raman enhancement,fluorescent probes,drug carriers,etc.,but they were not prepared biocompatible and stimuli-responsive drug loading microspheres.They unexplored the affect of encapsulation method,drug encapsulation efficiency,drug loading content,and drug release rate.Therefore,in this thesis,PVP is used as a stabilizer in room temperature and ethanol media,and thiol-isocyanate/ene click dispersion polymerization is used to prepare thiol-isocyanate/ene click particles in one pot,and the pH/GSH reduction responsiveness is explored.Further prepare DOX-loaded thiol-isocyanate/ene polymer microspheres to explore the effects of crosslinking degree,DOX content and hydrophilicity on the drug encapsulation efficiency and drug loading efficiency;study the effects of DOX treatment method on the DOX-loaded method、drug encapsulation efficiency and drug release rate.The main work of the thesis is as follows:1.Preparation of thiol(4-SH)-isocyanate(2-NCO/3-NCO)/ene(2-C=C-)two-component polymer microspheres:using the monomer tetrakis(3-mercaptopropionic acid)Pentaerythritol ester(PETMP)and L-lysine diisocyanate(LDI)/L-lysine triisocyanate(LTI)click-disperse polymerization to obtain multi-bumped,smooth thiol-isocyanate polymer microspheres;using monomer PETMP and N,N’-bis(acryloyl)cystamine(CBA)click dispersion polymerization to obtain monodisperse,smooth surface thiol-ene polymer microspheres.And explore the effect of monomer addition content on particles composition,morphology and size.The control results in particles with relatively good monodispersity and relatively small particles size to explore their pH responsiveness.2.Research on the pH responsiveness of the PETMP+LDI/LTI(6+6 mmol)particles:add the particles to the PBS buffer with pH=5.6,observe the morphology of the particles under different times through SEM,and find that the particles change from spherical to fibrous;then add the fibrous product into a PBS buffer at pH=7.4 to transform into a spherical shape,confirming the successful preparation of pH-responsive thiol-isocyanate click particles.Research on the pH and GSH reduction responsiveness of PETMP+CBA(0.75+0.75 mmol)particles:thiol-ene click particles changed from spherical to fibrous in PBS buffer solution at pH=5.6,and fibrous products were buffered in PBS at pH=7.4 The fibrous turned into spheres again.It shows that the thiol-ene polymer microspheres have pH responsiveness;the mass loss rate of the particles in C(GSH)=10 mM PBS solution at 72 h is 52%,indicating that the thiol-ene particles have GSH reduction responsiveness.Confirmed that we successfully prepared pH/GSH reduction responsive thiol-ene click particles.3.Preparation of DOX-loaded thiol-isocyanate polymer microspheres:adding the third component DOX to the PETMP+LDI/LTI(6+6 mmol)system,and using one-step dispersion polymerization to prepare DOX-loaded thiol-isocyanate polymer microspheres,explore the factors that affect the DOX-loaded method,drug encapsulation efficiency,and release rate.The.results show that:in PETMP+DOX+LDI(5.9312+0.0688+6 mmol)particles,when DOX is treated with tris,the drug encapsulation efficiency and release rate are 51.8%and 36%,respectively;when DOX is treated with TEA,the drug encapsulation efficiency and release rate were 78%and 0,respectively;when DOX was untreated,the drug encapsulation efficiency and release rate were 72%and 52%,respectively.It shows that the DOX treated by tris is partly physical loading and partly chemically bonding;the DOX treated by TEA is mostly chemically bonding;the untreated is mostly physically loading.The chemically bonding is beneficial to DOX-loaded,and the physical loading is beneficial to DOX release.Increasing the DOX content,the degree of crosslinking,the drug encapsulation efficiency and drug loading content increase accordingly.Increasing the hydrophilicity,the drug encapsulation efficiency and drug loading content decrease accordingly.The results of MTT experiments show that PETMP+DOX+LTI/LDI(6+6 mmol)particles is non-toxic to HUVEC cells and has good biocompatibility;PETMP+DOX+LDI(5.9312+0.0688+6 mmol)particles have can effectively kill Hela cells.4.Preparation of DOX loading thiol-ene polymer microspheres:DOX-loaded thiol-ene particles were prepared by one-step dispersion polymerization in ethanol medium,and the effect of changing monomer content on the drug encapsulation rate was investigated.The results showed that increasing DOX content will increases the DOX encapsulation efficiency and loading efficiency.