Synthesis And Properties Of Compolymers Analogous To Nucleic Acid, And Preparation Of A Fluorescent Vesicular Sensor For Saccharides

Nucleic acids are biological macromolecules and important life genetic materials, including DNA and RNA, DNA can form a double helix structure and which is the basis of replication and genetics. Seen from the chemical structure of DNA ,we found that it is an amphiphilic block copolymer, in which structure the lipophilic segment is nucleotides,and the hydrophilic segment is phosphate, the alternating arrangemernt of lipophilic and hydrophilic segment lead the DNA chains self-assemble into double helix structure,which relys on lipophilic hydrophobic interaction and the hydrogen bonds rccognization between nucleic acid bases on two single nucleotide chain, The lipophilic hydrophobic interaction and hydrogen bonding are also widely exist in supramolecular chemistry, and are offen be applied to design and construct artificial supramoleculars . Simulating the structural features of nucleic acids, design and synthesis polymers imitated to nucleic acids might make it self-assembe into helical aggregates in aqueous solution. Helical polymers have unique asymmetric catalysis and molecular recognition properties, Revealing the molecular characteristics of helix structure and simulating functions of biological spirochetes is an attractive subject.In addition, the nucleic acid has a wide range of medical, medicinal value, can be used in synthesis of anti-virus inhibitors and anti-cancer drugs.The molecular rcogniiong based on nucleic acid has a widly attention in recent years. The synthesis of nucleic acid polymers can not only imitate the helix structure of DNA and understand its causes for formation,but also pack the substuate drugs taking advantang of hydrogen bonding identification. effectively preventing competition of water in environment. Reducing the side effects and increased loading of drugs. Because of the imitation of nucleic acid ,the polymer might be used to difficult cancer medical field, which could become a new method to prepare anti-cancer drugs.1 Synthesis of copolymers PCASE and PCTSETo simulate the structure of DNA, we synthesized two biodegradable copolymers PCASE and PCTSE containing nucleic acid bases and aza-crown ethers in main-chain, using isophthalic acid ester to replace the lipophilic nucleotide, and the water-soluble aza-crown ether to replace the phosphate.. 1H NMR proved that functional groups of nucleic acid bases exist and not chang in the the polymerization process. This is the foundation for next molecule recognition. The average molecular weight of the copolymers are determinated by GPC.2 The morphology of copolymers before and after reconnizing with subtrate molecularsScanning electron microscopy showed that copolymer PCASE formed silk ribbon width of about 100nm aggregates in pure aqueous solution , After 20 days at room temperature the silk ribbon reversed and distorted into hollow spiral aggregates. The self-assemble phenomenon of copolymer PCASE in pure aqueous solution is very similar to the behavior of DNA . Unlik copolymer PCASE the copolymer PCTSE form nanospheres , possibly because of their different aggregation tendency cased by different nucleic acid bases in main-chain, The copolymer PCASE can not self-assemble into double helix structure like DNA, probably due to the single adenine in structure,which can not recognize with complementary nucleic acid base in another copolymer chain like DNA. So we observe the morphology of copolymer PCASE and PCTSE after their recognization, we found that these two copolymers did not form expected double helix aggregates,but formed a long strip of willow-shaped aggregates, We believe the different aggragation tendency of two copolymers in aqueous solutions as well as the different polymerization are the reasons why they can not form double-helix aggregates.We know that crown ethers exist as soft chain in the water, and after recognizing with metal ions, the crown ethers ring will open. This makes it possible to change the entire crown ether polymer aggregation state in aqueous solution. We chosed potassium ions best for 18-crown-6 to adjust the aggregation of polymers in aqueous solution, The copolymer PCASE aggregates changed from into rod-like, and some show spiral or hollow rod-like nano-tubes in the presence of potassium ions, this phenomenon shows that potassium ions indeed can change the crown ether copolymer aggregation state in aqueous solution . We have also tried to regulate the aggregation morphology of copolymer PCTSE or copolymer with subtrates ,as well as two copolymer after recongnzation.it was found that the potassium ions can not effect the aggregation morphology of copolymer PCTSE(or PCASE/PCTSE+subtrates).but effect the aggregation morphology of the two copolymer aggregation morphology after their recognization,changed from original s willow strips to irregular spindle-shaped aggregates.3 Study of molecular recognizaion of the copolymers and complementary basesThe C2=O of thymine in copolymer PCTSE did not change,and the C4=O peak changed from 1670cm-1 to1664 cm-1.after recognizing with copolymer PCASE, this result shows the formation of hydrogen bonds between C4=O of thymine in copolymer PCTSE and -NH2 of adenine in copolymer PCASE. The C4=O peak changed back from 1664cm-1 to1670 cm-1.after heating to 130℃shows the break of hydrogen bonds. Seen from the changes upon 3000cm-1,we found the -NH2 of copolymer PCASE and-NH of copolymer PCTSE disappeared, a new peak 3409 cm-1 appeared, which will gradually disappeared with the temperature up to130℃, and the -NH 3315 cm-1 of the copolymer PCTSE emergence again, which shows that at room temperature the -NH2 of copolymer PCASE recognized with C4=O of thymine in copolymer PCTSE, and the hydrogen bonds gradually break in high temperature.In summary ,we have designed and synthesized two copolymers PCASE and PCTSE,we observed their morphology in aqueous solution,and tried to adjusted their aggregation state.We have also studied their molecular recognization between their themselves and with substrates.This might be a new approach to mimic bio-artificial helix, and develop new nucleic acid drug carrieres .In the fifth chapter, we have also designed and synthesized a new fluorescent vesicular sensor for saccharides,and applied it to testing human urine glcose for the first time.