Study On Preparation And Drug Release Of Asugarcane Bagasse Cellulose-based Nanogels

Nanogel is a nano-scale swollen polymer network in aqueous dispersion formed by polymers through covalent or non-covalent interactions.With the unique characteristics of strong hydrophilicity,biocompatibility,high drug loading and release efficiency as well as the ability to respond to external stimuli,the nanogel is considered to be one of the most promising carrier for the controlled release of drug.In this study,sugarcane bagasse cellulose was used as the main raw material to prepare a nanogel with multiple stimuli responsiveness by a free radical polymerization method,and much effort has been made to reveal the behaviors of the nanogels in drug loading and release in an attempt to explore its various applications.The main research contents and results are as follows:?1?The cellulose content of sugarcane bagasse was increased from 59.0%to 83.3%and91.2%by using hydrothermal treatment and a"two-step method"which followed by exposure to sodium chlorite and potassium hydroxide for pretreatment,respectively.The results of FTIR,SEM and XRD measurements showed that pretreatment could destroy most of the original structure of sugarcane bagasse fiber,removed hemicellulose and lignin from sugarcane bagasse effectively,and reduce the crystallinity.?2?Sugarcane bagasse cellulose was further oxidized by HNO₃/H₃PO₄-NaNO₂system.The results from the SEM and XRD measurements show that the oxidation reaction aggravated the destruction and erosion of the original structure of cellulose,and most of the crystal structure I of cellulose was transformed to the crystal structure II.FTIR and carboxyl content analysis results indicated that oxidized sugarcane bagasse cellulose?O-SBC?contained a relatively large amount of carboxyl group,implying the success of oxidation reaction.The results from single-factor experiment showed that both the amount of oxidant and the oxidation time had great influence on the oxidation reaction.Increasing the amount of oxidant and extending the oxidation time could increase the carboxyl content of O-SBC,but meanwhile lead to more mass loss of bagasse cellulose.?3?Methacrylic anhydride modified oxidized sugarcane bagasse cellulose?MA-O-SBC?and N-isopropylacrylamide?NIPAM?was used to synthesize nanogels by an in situ free radical copolymerization.The results of SEM and high-precision particle size analyzer showed that the nanogels had stable shape with the average particle size around 183 nm and the degree of swelling up to 529.0%.Moreover,the nanogel paricles were well dispersed in aqueous medium.Fluid morphology analysis of the nanogels demonstrated that the nanogels had stimulus responsiveness to reducing agent and temperature.Cytotoxicity test showed the survival rate of cells cultured in the nanogels dispersions for 24 h was higher than 80.0%,indicating that the nanogels had good biocompatibility.?4?The model drug doxorubicin hydrochloride?DOX?was loaded into the nanogel by infiltration and electrostatic association.It was found that the nanogels had the best drug loading capacity at p H8 and the drug loading efficiency was up to 82.7%.According to the simulated release experiments,the drug-loaded nanogel remained stable in water,and the release efficiency of DOX was only 6.7%after 96 h;whereas the cumulative release efficiency of DOX was up to 81.0%synergetic stimuli responsiveness to the presence of reducing agent,as well as the changes of temperature and p H in the systems.Overall,the drug release can be precisely controlled by such synergistic effects.