Synthesis And Performance Of Stimulu-responsive Drug Carriers Based On Core-shell Structure

Stimuli-responsive nanocarriers have many advantages,which can not only improve the stability of the drug,overcome the problems of poor solubility,low bioavailability,lack of selectivity,etc.,but also control drug release according to dosage,duration of treatment and treatment location,thereby improving drug treatment and reducing side effects on normal tissues.Two kinds of stimuli-responsive nanocarriers with core-shell structure were prepared by free radical polymerization,using magnetic mesoporous silica as the core,functional polymer as the shell and doxorubicin hydrochloride?DOX?as the model drug.The nanocarrier?Fe₃O₄/mSiO₂/P?MAA-co-NIPAM??and another nanocarrier?Fe₃O₄/mSiO₂/CMCS-PDMAEMA?were prepared by using magnetic mesoporous silica as the core,methacrylic acid?MAA?,carboxymethyl chitosan?CMCS?,2-?Dimethylamino?ethyl methacrylate?DMAEMA?as pH-responsive monomers,Nisopropyl acrylamide?NIPAM?as a temperature-sensitive monomer.The preparation process was optimized by single factor experiment.The structure and properties of the product were analyzed by FTIR,TG,VSM,XPS,SEM,TEM,XRD and so on.By studying on drug adsorption and in vitro release of Fe₃O₄/mSiO₂/P?MAA-coNIPAM?and Fe₃O₄/mSiO₂/CMCS-PDMAEMA,the results show that the two drug carriers have the best adsorption property for DOX at pH = 7.The equilibrium adsorption capacity,drug loading rate and encapsulation efficiency of Fe₃O₄/mSiO₂/P?MAA-coNIPAM?reach the maximum values of 114.32 mg/g,11.43% and 76.21%,respectively,while the maximum values of Fe₃O₄/mSiO₂/CMCS-PDMAEMA are 66.21 mg/g,6.62% and 44.14%,respectively.The adsorption process of Fe₃O₄/mSiO₂/P?MAA-co-NIPAM?is consistent with the Langmuir thermodynamic model and pseudo-second-order kinetic model.The adsorption thermodynamics of Fe₃O₄/mSiO₂/CMCS-PDMAEMA is consistent with Langmuir model at 25 ?,but more consistent with Temkin model at 35 ? and 45 ?.The adsorption kinetics of Fe₃O₄/mSiO₂/CMCS-PDMAEMA is in accordance with the pseudo-secondorder kinetic model.Fe₃O₄/mSiO₂/P?MAA-co-NIPAM?is a pH and temperature stimulus-responsive drug carrier and can control the drug release amount by changing the pH and temperature.When the pH value is 6,the maximum drug release rate is 93.43%.And when the temperature is 40 ?,the maximum drug release rate is 81.38%.Fe₃O₄/mSiO₂/CMCS-PDMAEMA is a pH-responsive drug carrier.When the pH value is 3,the maximum drug release rate is 16.55%.The release process for DOX of the two drug carriers belongs to the Korsmeyer-Peppas model.Figure 52;Table 14;Reference 65...