Preparation And Properties Of Novel PH/Glutathione Double-Responsive Nanocarriers

Proanthocyanidins(OPC)have many physiological functions such as anti-oxidation,anti-diabetes,anti-cancer,and neuroprotection,but their strong biological activity is sensitive to pH,temperature and light,which limits their applications in food,medicine,cosmetics and other fields.Therefore,the proanthocyanidins can be loaded and protected by preparing nanoparticles.Hyaluronic acid has good biocompatibility as a natural polysaccharide,but unmodified hyaluronic acid is difficult to cope with adverse environments such as acid,alkali and heat.Therefore,it can be prepared into nanoparticles by modifying the chemical groups on its main chain to improve its stability.Responsive nanoparticles have great development prospects.They can be combined with specific parts through active targeting,and then the responsiveness of the carrier to the environment can be achieved to control the release of the core material,effectively solving the problem of transport and release of the core material in the body.In this paper,hyaluronic acid was used as raw material to prepare polymer nanoparticles with pH/glutathione responsiveness based on the microenvironment in the body.The OPC was embedded and related properties were studied.The main research contents and results are as follows:1.Ultrasound-assisted method was selected to modify hyaluronic acid by histidine to give its pH response characteristics,and the effects of ultrasonic power,temperature,time and substrate mass ratio on the grafted polymer were investigated.The conditions of ultrasonic power,reaction temperature and substrate ratio in the synthesis process were optimized by response surface methodology.The optimal reaction conditions were as follows: ultrasonic power was 249 W,reaction temperature was 48°C,substrate mass ratio was 3.1,the reaction time was 40 min,and the predicted degree was 36.8%.Then,N'N-bisacrylylcystamine as crosslinking agent,disulfide bond was introduced into the synthetic material under the action of the catalyst to impart glutathione sensitivity to the polymer.The proton buffer capacity test and the reduction degradation test were used to preliminarily detect the response characteristics of synthetic substances.The synthetic materials were characterized by infraredspectroscopy,thermogravimetric analysis,differential scanning calorimetry,X-ray diffraction and scanning electron microscope.2.Nanoparticles with dual pH/ glutathione responsiveness were prepared by ultrasonic dispersion method.When the ultrasonic power was 180 W and the ultrasonic time was 10 min,the average particle size of the prepared nanoparticles was 162 nm and the PDI value was0.254.By exploring the effect of different pH and GSH concentrations on the nanoparticles,the responsiveness of the nanoparticles was detected.When the pH was increased from 5.0 to7.5,the average particle size and PDI of the nanoparticles decreased continuously,and the absolute value of the Zeta potential kept increasing.As the GSH concentration increases from10 ?M to 10 mM,the average particle size and PDI also increase,and the nanoparticles were able to maintain a certain stability at higher temperatures and in the gastrointestinal environment.3.The OPC is embedded as a core material,and the encapsulation rate reached 88.5%.By embedding,the reduction of antioxidant properties of OPC during heat treatment can be delayed,and the destruction of OPC by food preservative can be prevented to a certain extent.At pH=5.8 and GSH concentration of 10 mM,the release rate of loaded OPC nanoparticles reached the highest,and the cumulative release rate reached 78.4% at 30 h.The toxicity of loaded OPC nanoparticles on colon cancer CMT93 cells was detected by MTT assay.The loading of OPC nanoparticles showed an increasing inhibition rate with the increase of OPC concentration,and the cytotoxicity increased with the extension of incubation time.The results of cytocompatibility analysis of BAC-HA-His nanoparticles showed that after treating cells for 72 h with BAC-HA-His nanoparticles at a concentration of 1 mg/mL,the survival rate was still maintained 85%,indicating that the nanoparticles were non-toxic and had good cell compatibility.