Preparation Of Hydrogels Based On Biopolymer And Their Controlled Release For Drug

The hydrogel,a three-dimensional network structure with water as a dispersion medium,is soft and flexible,and similar to rubber and jelly.As the main feature,the hydrogel absorbs large amounts of water and remains aninitial and inherent shape in water,but does not dissolve in water.Generally,hydrogel has strong adsorption capacity due to its cross-linked microstructure with a lot of pores.Because of its unique internal structure,hydrogel has been favored in the medical field as a drug release material.According to the network bonding force manner of hydrogel,it can be divided into physical hydrogel and chemical hydrogel.And according to the response of hydrogel to external stimuli,it can be divided into traditional hydrogel and stimuli responsive hydrogel.Traditional hydrogel is not sensitivity,while stimuli responsive hydrogel can self-swelling or shrinking with the changes of the external environment such as temperature,pH,light,electric field,ion intensity,light,etc.Since the hydrogel possess the remarkable properties,it isused as sensors,controls release switches,and so on.At present,besides of traditional bulk hydrogel,other hydrogels with specific shape and designed size,for instance,hydrogel microspheres and nanogel,have been greatly developed.Compared to traditional bulk hydrogel,the hydrogel microspheres have a small volume which facilitates the implantation of the human body to achieve the targeted release of drugs.In addition,the nanogel with nanoscale structure,easily penetrates various protective films in the body,and has more extensive application valuein medicine field and non-medical fields.It is a major idea that the sustainable biopolymeric materialwith non-toxic,biodegradable,and biocompatible is mainly designed and developed in thematerial field.Hence,as an important strategy,the sustainable biopolymeric materialis fabricated by using biopolymers as raw materials.In the current academic dissertation,soy protein isolate(SPI)was chose as raw material,and acrylic acid(AA)as monomer by different polymerization methods to control the morphology of the hydrogel.Bulk hydrogels,hydrogel microspheres and nanogel were successfully prepared respectively.Furthermore,the water absorption and drug release properties of hydrogel were explored.Firstly,SPI/PAA composite hydrogel was prepared by solution polymerization.The macro-shape of the hydrogel was similar to transparent jelly.SEM microstructure showed a distinct three-dimensional network structure with a large of pores.The influence of the mass ratio of SPI and AA on the macroscopic morphology was investigated.Meanwhile,the influence of swelling performancewas also studied such as BIS,APS,and GA by a large number of experiments.The optimal reaction condition was defined,and the swelling degree of the hydrogel was up to 176 g/g.It was confirmed that the hydrogel was pH-sensitivity according to the swelling behavior.With bovine serum albumin(BSA)as a mimic drug,the loading capacity of dry hydrogel was up to 0.5 g/g in phosphate buffer with pH=7.4 and 0.01 mol/L ionic strength.Then,the cumulative release rate reached to 90%.Secondly,SPI/PAA composite hydrogel microspheres were prepared by inverse suspension polymerization.SPI was dissolved in the solution of NaOH as the aqueous phase,and petroleum ether was chose as the oil phase.Sodium dodecyl sulfate(SDS)was selected as an emulsifier,span80 as a co-emulsifier,ammonium persulfate(APS)as the initiator,and N,N'-methylenebisacrylamide(BIS)as the crosslinker,respectively.The macroscopic structure of the hydrogel microspheres were spherical particles,the diameter could be controlled of AA,and the diameter was controlled between 0.8-4mm.Ttherefore,the macroscopic morphology of the hydrogel microspheres were successfully controlled.SEM microstructure showed a pronounced spherical profile and pore structure.With benzalkonium chloride as a mimic drug,the loading capacity of dry hydrogel microspheres were up to 26.92mg/g in phosphate buffer with pH=7.4 and 0.01 mol/L ionic strength.After that,the cumulative release rate reached to 60%-70%.Finally,SPI/PAA nanogels were prepared via the inverse emulasion polymerizationin water/oil mixture.The inverse emulasion polymerization was performed by using AA as monomer,APS as iniator,BIS as the crosslinker,SDS as an emulsifier,span 80 as a co-emulsifier.It was amazing that the nanogel be successfully prepared without emulsifiers by controlling feed material.SEM microstructure structure showed clear,uniform spherical structure with a diameter of 80nm-200 nm.The DLS data results showed that the nanogel particle size distribution was 200-800 nm.Zeta potential results showed that the nanogel charged electropositivity,it was proved that the pH of the prepared nanogel was lower than the isoelectric point of the SPI.With benzalkonium chloride as a mimic drug,the loading capacity of dry nanogelwas up to 26 mg/g in phosphate buffer with pH=7.4 and 0.01 mol/L ionic strength.Afterwards,the cumulative release rate reached to 60%-80%.In this dissertation,three new composite hydrogels were obtained using the same raw materials but different polymerization methods.The macroscopic morphology of hydrogels was successfully controlled by selecting the polymerization mothods and the different proportion of raw materials.Furthermore,the microstructure and size of the hydrogel was further adjusted.The composite hydrogel exhibited high water absorption,and had a good loading effect for proteins and small molecule drugs,and realized effective controlled release.They will be explored their application in the environmental and biomedical field.