Study On The Synthesis And Function Of Biomaterials Based On The Collaborative Assembly Of Biomacromolecules

Biomaterials are a kind of new materials used to diagnose,treat,repair or replace human tissues,organs or enhance their functions.They are not drugs in themselves,but play a role through direct combination and interaction with biological systems.Biomaterials are mainly applied in medicine,biology,materials science and other disciplines to solve the functional defects caused by diseases or injuries,and their functions cannot be replaced by drugs.With the rapid development of modern medical level and the progress of production mode,the demand for biomaterials in human society is increasing day by day,and the demand for biomaterials is also higher and higher,which also promotes the development of biomaterials towards a more green,environmental protection and efficient direction.Biomaterials can be divided into many types according to different standards.Natural polymer materials are favored for their remarkable renewability,good compatibility and degradability.The development of biomaterials based on natural polymers and the possibility of its application in tissue engineering and regenerative medicine are of great scientific and practical significance for the development and utilization of biomaterials.As a natural polymer,silk sericin?SS?has good hydrophilicity,biodegradability,oxidation resistance and biocompatibility.It is an ideal resource for the development of protein biomaterials.For a long time,sericin has been used as the waste of silk degumming process.So far,researchers at home and abroad have made extensive attempts to modify sericin,including crosslinking,blending or compounding sericin protein with natural fiber,high polymer and nano materials to improve the mechanical properties of sericin.However,its application as biomaterials has just started;cellulose has been used to improve the mechanical properties of sericin As the most abundant natural polymer in nature,it is one of the most abundant polysaccharide raw materials on the earth.Cellulose has the advantages of good biocompatibility,biodegradability,non-toxic and harmless.Carboxymethylcellulose is a derivative of cellulose,soluble in water,with good dispersion,emulsification,adhesion,thickening and other characteristics,has been widely used in food,paint,paper,medicine,textile and other fields;in traditional concepts,scholars emphasize DNA as the carrier of genetic information,but DNA as a functional material which can be assembled has quietly emerged.Compared with polymers,DNA has many unique advantages,such as stability,addressability and programmability,which make DNA open the door of functional materials as controllable assembly primitives.In this study,we developed self-assembly materials based on sericin,carboxymethylcellulose and DNA,and the following research results have been achieved:1.Preparation and application of cellulose plasticized sericin composite film based on covalent crosslinkingThe dialdehyde carboxymethylcellulose containing 36.52%±0.63%aldehyde group was prepared by selectively opening the single bond at C₂ and C₃ positions of glucopyran ring and oxidizing the hydroxyl groups on the two carbon atoms to aldehyde group.Dialdehyde carboxymethylcellulose has good reactivity and can react and couple with amino group in sericin.By solution casting,we prepared the sericin composite membrane plasticized by dialdehyde carboxymethylcellulose.The crosslinking degree,mechanical properties and hydrophilicity of the composite membrane were evaluated.The results showed that the crosslinking degree of the composite membrane increased with the increase of the content of dialdehyde carboxymethylcellulose.When 12%dialdehyde carboxymethylcellulose was added,the composite membrane had the best comprehensive mechanical properties,suitable hydrophilicity and strong water retention capacity.It was found by scanning electron microscopy that the dialdehyde carboxymethylcellulose particles were dispersed in sericin.With the increase of the content of dialdehyde carboxymethylcellulose,the particle density increased.The results of blood compatibility test showed that sericin had good blood compatibility.The addition of dialdehyde carboxymethylcellulose further improved the blood compatibility of sericin composite membrane.Compared with the control group,the cells on the sericin composite membrane can proliferate normally and have good biocompatibility.2.Preparation and application of cellulose biosensor based on organometallic frameworkThe silver ions in the solution were reduced to nano silver by the protonated hydroxyl groups in carboxymethylcellulose through orthogonal experiments,and the nano silver sol with carboxymethylcellulose framework was obtained.As a reducing agent,increasing the amount of carboxymethylcellulose promoted the synthesis of nano silver.The increase of pH value leads to the deionization of carboxymethylcellulose,which improves the chelating ability of carboxymethylcellulose and the synthesis of nano silver.The increase of temperature increases the activation energy,the equilibrium constant,the reaction speed and the synthesis of nano silver.Increasing the amount of silver nitrate can also promote the synthesis of nano silver.The interaction between sulfhydryl group and nano silver results in the change of absorption of nano silver in the visible region.Due to the effect of plasma resonance,carboxymethylcellulose can change the color of silver nitrate cysteine solution,so as to achieve the purpose of selective detection of cysteine.3.Preparation and Application of Dynamic DNA HydrogelFour DNA single chains of HG-1A,HG-2A,A8 and 2Ac were designed independently,and the ratio of HG-1A to HG-2A was adjusted by polyacrylamide gel electrophoresis to complete self-assembly at the molar ratio of 2:1.The results of circular dichroism analysis show that when the buffer pH changes from 8.0 to 5.0,the molecular ellipticity of DNA chain decreases and the wave peak shifts to the right.It shows that when the buffer pH is 5.0,the hg-2a chain has C-C⁺pairing and electron cloud superposition,forming i-motif structure.Rheological experiments show that the DNA gel has good mechanical properties and good pH responsiveness,and its mechanical properties change with the change of pH.After adding A8 chain to the system,tttttt-structure in hg-1a chain formed a double helix structure through complementary pairing,which increased the mechanical properties of the system.After joining the 2Ac chain,the partial pairing of HG-2A and 2Ac bases makes the i-motif domain lose the ability to respond to pH.It is proved that the pH response unit of DNA gel is i-motif region.