Preparation And Application Starch-based Hydrogel Microspheres Based On Reactive Spray Drying

Hydrogel microspheres not only possess the various excellent properties of hydrogels,but also have the advantages of responding the stimulation of external environment quickly,so they have potential to be applied in the fields of drug delivery,sensor and water treatment.Starch is a natural polymer material that is widely found in nature and is an excellent raw material for preparing hydrogel microspheres.Spray drying,as an efficient and scalable production method for preparing microspheres,has received widely attention.To this end,this study used starch and starch derivatives as raw materials,three kinds of starch-based hydrogel microspheres were prepared via chemical reaction during spray drying.The structure and properties of three kinds of starch-based hydrogel microspheres were characterized.Additionally,their applications in drug slow release and water treatment were also studied.The dissertation mainly includes the following three contents:（1）The starch was not only esterified with N-maleoyl alanine to prepare starch dienophile,but also esterified with succinic acid amide to prepare starch diene.Then,starch-based single network hydrogel microspheres（SGPs）and 5-Fu drug-loaded starch-based single network hydrogel microspheres（5-Fu/SGPs）were fabricated via the combination of spray drying and Diels-Alder reaction,using two kinds of esterified starches as raw materials,H₂O as a solvent and 5-fluorouracil（5-Fu）as a model drug.In addition,the conditions for preparing SGPs were optimized,and the SGPs were characterized by FTIR,SEM,TG and so on.Finally,the swelling behavior of the SGPs and drug release behavior of the 5-Fu/SGPs were studied,respectively.The results indicated that the swelling property of the SGPs could be adjusted by controlling the conditions of spray drying and the SGPs were non-toxic for model cells;Besides,the 5-Fu/SGPs slowed the release rate of 5-Fu but did not lessened the action effect of 5-Fu on cancer cells.（2）Starch-based composite hydrogel microspheres（HMs）were prepared from carboxymethyl chitosan and hydroxyethyl starch via the combination of spray drying and base-catalyzed nucleophilic substitution reaction,using epichlorohydrin as the crosslinking agent.Furthermore,the conditions for preparing HMs were optimized,the structure and properties of the HMs were characterized.At the same time,the influence of HMs on the adsorption behavior of two dyes（MB and Eosin Y）and three heavy metal ions(Cu²⁺,Cd²⁺and Ni²⁺)were investigated.The experimental results showed that HMs possessed p H and salt sensitiveness;Besides,as one kind of broad-spectrum adsorbent,the maximum adsorption capacities of HMs for MB,Eosin Y,Cd²⁺,Cu²⁺and Ni²⁺were 106.97 mg/g,143.55 mg/g,32.51 mg/g,47.87 mg/g,and27.18 mg/g,respectively.（3）First,the hydroxypropyl-β-cyclodextrin and starch were modified with N-maleoyl-β-alanine and succinic acid amide to prepare the dienophile and diene,respectively.Second,aminated magnetic halloysite nanotubes and terpolymer were prepared.Then,the as-prepared diene,dienophile,magnetic halloysite nanotubes and terpolymer were dispersed in deionized water,starch-based magnetic semi-interpenetrating network hydrogel microspheres（SMSHMs）were produced via a Diels-Alder reaction during the spray drying.Finally,the structure and properties of the SMSHMs were characterized and the adsorption behavior of SMSHMs for methylene blue was investigated systematically.The results indicated that SMSHMs could effectively remove methylene blue in waste water.With the increase in the adsorption temperature,the equilibrium adsorption capacity of SMSHMs increased.Meanwhile,the adsorption processes both fitted well Langmuir isothermal model and pseudo-second-order kinetic model.In addition,the introduction of aminated magnetic halloysite nanotubes endowed the SMSHMs excellent magnetic properties,which could be easily recycled under an external magnetic field.