Preparation,Properties And Application Of Three Alginate-Based Hydrogels

Hydrogel have excellent physical and chemical properties,including high water content,porous structure,optical properties and mechanical properties.This provides infinite possibilities for the application of hydrogel in many fields.Firstly,hydrogel is a kind of macromolecular material with high water content,which is similar to the extracellular matrix in natural tissues,and is commonly used in tissue engineering scaffolds.Secondly,viscoelastic conductive hydrogel composed of hydrophilic polymers,which have good electrical conductivity and mechanical properties,are commonly used to build sensor.Finally,hydrogel with adjustable porous structure are often used for biosorption or membrane filtration.Although the application research of hydrogel in different fields has made great progress,due to the influence of single monomer composition of synthetic hydrogel,the hydrogel prepared by them often have defects of single function,simple structure and narrow application range.At present,it is still a major challenge for researchers to design hydrogel with diverse functions,complex structures and wide applications.Alginate is a natural polysaccharide polymer extracted from marine brown algae,which has good biocompatibility and biosafety.The preparation of alginate-based hydrogel with diverse functions and the expansion of their applications in biomedicine,sensor monitoring and chemical analysis are of positive and profound significance.Based on these,the idea of combining alginate with some functional monomers to prepare novel alginate-based hydrogel composites was proposed.In this study,based on sodium alginate,polyacrylamide,polyacrylic acid and liquid metal,a variety of alginate-based hydrogel composites with good performance were designed and synthesized,and successfully applied to the construction of artificial blood vessel,multifunctional sensor and filter membrane.The main results of this dissertation are as following:1.A alginate-based hydrogel(PMSA)of polyacrylamide(PAAm),N,N-methylenebisacrylamide(MBA)and sodium alginate(SA)was designed and applied to the construction of artificial blood vessel.PLA molds with various sizes and structures were prepared by 3D printing technology,and PMSA hydrogel tubes with single-layer and double-layer structures of various sizes were prepared by one-step pouring molding,especially the small diameter hydrogel tubes with diameter less than 6 mm.By adjusting the ratio of SA,AAm and MBA,the PMSA hydrogel tube with the best pore size and mechanical properties was prepared.The results of MTT cytotoxicity assay showed that PMSA hydrogel tube has good biocompatibility in vitro.The results of permeability test and hemolysis test(hemolysis rate < 5%,in line with the national standard of biomaterials)showed that PMSA hydrogel tube has good blood compatibility.The results of subcutaneous implantation showed that PMSA hydrogel tube has good biocompatibility in vivo.The results of cervical vein replacement in rabbits showed that PMSA hydrogel tube could be used as artificial blood vessel for transplantation.This 3D printing mold one-step perfusion molding method is a simple and effective new method to construct small diameter artificial blood vessel,which has potential application value in vascular tissue engineering.2.A alginate-based conductive hydrogel of liquid metal(LM),sodium alginate(SA)and polyacrylic acid(PAA)was designed and applied to the construction of multifunctional sensor.A new type of alginate-based conductive hydrogel(LM-SA-PAA)was prepared by in-situ polymerization of acrylic acid(AA)in SA encapsulated LM nanoparticles(LMNPs)colloidal suspension by ultrasonic method.The double crosslinked polymer network(physical crosslinked network,chemical crosslinked network)endows LM-SA-PAA hydrogel with excellent tensile properties(> 2200%),self adhesion,self-healing and high sensitivity.Based on the characteristics of LM-SA-PAA hydrogel,temperature and respiration sensor with thermal sensitivity up to 6.7 %/℃ were constructed respectively;In the 250% strain range,the strain coefficient was 1.28,and the linearity was 0.98.It was a strain sensor used to monitor the bending movement of fingers,wrists and elbows;Capacitive and resistive pressure sensor for detecting compression pressure;Handwriting pad for recognizing handwriting;And ECG monitoring device for monitoring ECG signals.The multifunctional sensor based on LM-SA-PAA hydrogel has proved to be a promising platform,which is expected to be used in the fields of human activities,EMG and ECG detection.3.A alginate-based hydrogel filter membrane was designed,through which a filter device for the pretreatment of HPLC biological samples was constructed.The manufacturing process of the device was simple and fast,and could be customized in batches.The device could realize fast and simple biological sample pretreatment process.SA hydrogel membrane had excellent mechanical properties,suitable porosity and durability.The rejection rate of BSA by the membrane was as high as95%,and it could maintain the rejection rate of more than 95% for 7 days.The results of dye filtration test showed that the filtration rate of the membrane was more than 96%for methyl orange(327 D),carmine(604 D),brilliant blue(792 D)and vitamin B12(1355 D)with different molecular weights,and the filtration performance remained stable within 7 days of continuous use.The pretreatment of urea(60 D),creatinine(113 D),uric acid(168 D),colchicine(399 D)and vitamin B12(1355 D)in biological samples were carried out through SA hydrogel filter membrane.Under the HPLC chromatographic conditions established in this study,the five components to be tested could be separated sensitively,rapidly,and accurately.Compared with the current biological sample pretreatment methods,SA hydrogel filter membrane was used for biological sample pretreatment,which simplifies the pretreatment process,reduces the detection cost and improves the detection efficiency while ensuring the security of chromatographic column,good accuracy of detection results and high sensitivity.This provides a certain reference value for the selection of filter membrane materials and the pretreatment of biological samples.In summary,this paper designed and synthesized a variety of alginate-based hydrogels,and successfully constructed artificial blood vessel,multifunctional sensor and filter membrane,which provided new ideas and widened the development space for the application of alginate-based hydrogels in tissue engineering,sensor monitoring and chemical analysis.