Basic Research On Preparation And Application Of Porous Nanocellulose Combined With Gas-solid Hydrolysis And Enzymatic Method

Cellulose is the largest biomass resource in nature,accounting for more than half of the plant's carbon content,and also has good biocompatibility and low toxicity.So it is often used in pharmaceutical,chemical,medical equipment and other aspects.However,the high degree of polymerization,large molecular weight,and poor solubility of natural fibers extracted from plants limit the application range of natural cellulose.Therefore,the cellulose needs to be modified to obtain the desired properties.Cellulose nanometerization is one of the methods for modifying cellulose.The nanometerized cellulose not only retains the properties of fibrils but also gives it high crystallinity,high mechanical strength,large specific surface area,good hydrophilicity and other characteristics.In this paper,based on the traditional preparation method of nanocellulose,a study on the preparation of nanocellulose by gas-solid acidolysis combined enzyme method was carried out.And completed the preparation process optimization,the characterization of porous nanocellulose and its preliminary application in drug delivery,including:(1)In the process of preparing porous nanocellulose by gas-solid acidolysis combined enzyme method,Process optimization was carried out on the experimental reaction conditions,and the optimal reaction conditions were judged with sedimentation volume and average particle size as the detection standards.The optimal conditions obtained are: Refined cotton is used as the raw material for the initial reaction.A hydrochloric acid solution with a solid-liquid ratio of 1g/2ml and a concentration of1.5mol/L is added.After reaction at 80°C for 6h,the same concentration hydrochloric acid solution with a solid-liquid ratio of 1g/0.5ml is added again.The reaction was sealed and stirred at 80? for 2h.Finally,the product was enzymatically hydrolyzed.The citric acid-sodium citrate buffer was selected.The amount of enzyme added was 6g(raw material)/0.1g.the enzymatic hydrolysis was stirred at 30°C for 16 h to obtain the best product.The prepared porous nanocellulose was characterized by dynamic light scattering,infrared,scanning electron microscopy,x-ray diffraction,thermogravimetric analysis,nitrogen adsorption,etc.To explore the unique porous structure of self-made nanocellulose to provide theoretical support for its subsequent application in drug delivery.(2)We chose the water-soluble drug aspirin,the insoluble drug fenbufen,and the soluble drug metformin hydrochloride as the drug model.Using microcrystalline cellulose as a comparative carrier,the drug carrying capacity and sustained-release effect of nanocellulose were preliminarily evaluated.At the same time,a gradient of drug loading is set to explore the effect of different drug loading on the sustained release effect of the drug.Finally,the kinetic model of intestinal fluid dissolution was fitted to the drug loading systems with different drug loadings to study the difference between the release characteristics of nanocellulose to different solubility drugs.The results show that due to the complexity of the self-made porous nanocellulose channels,the time for the drugs to migrate from the pores to the surface is increased for slightly soluble drugs and soluble drugs,so it has a certain sustained release effect.For insoluble drugs,the drugs re-form into nano-scale crystals in the pores during the loading process,which greatly increases the specific surface area of the insoluble drugs,so it has the effect of accelerated release.(3)Carry out the research on the tablet dosage forms of porous nanocellulose loaded with aspirin and metformin hydrochloride powder,mainly to investigate whether nanocellulose alone has the characteristics of compression moldability,disintegration and sustained release at the same time.The tablet formulation of the nanocellulose-loaded metformin hydrochloride system was optimized and compared with the commercially available Gehuazhi metformin hydrochloride sustained-release tablets.Prove whether it is possible to prepare a sustained release effect similar to it.The results show that nanocellulose has good compression moldability,disintegration,and a certain range of sustained release effect.The disintegration of homemade tablets is controlled by adding polyacrylic resin to prolong the drug sustained release time.When polyacrylic resin is added When the amount is 5%,the tablet can achieve the best sustained release effect.