Construction And Application Of Drug - Loaded Hydrogels Based On Aptamer Functionalization Of Nucleic Acids

Hydrogels with a three-dimensional polymer networks in which individual hydrophilic polymer chains are connected by physical or chemical bond have been one of the most appealing polymeric materials used for preparing sustained-release systems that have a great impact on pharmaceutical development and regenerative medicine. And also, the development of DNA aptamer technology accelerates the hydrogel application in the field of drug carrier.In the first chapter, we have given a general introduction of the drug carrier and the hydrogels, also, the development of the DNA aptamer technology and its main application status in the field of hydrogels are introduced.In the second chapter, an aptamer-functionalized hydrogel has been developed which can be regulated by the AS1411 aptamer with the gel-sol conversion. Also the hydrogel can be further utilized for controlled encapsulation and release of the cancer drugs. AS1411 initiates hybridization of acrydite-modi?ed oligonucleotides to form the hydrogels and the presence of the target protein nucleolin lead the gel to dissolve as a result of reducing the cross-linking density by competitive target–aptamer binding. Based on this, it is possible to utilize this material for storing and releasing molecules. And the cancer drug doxorubicin was encapsulated inside the gel in the formation of the hydrogel and then released in the presence of nucleolin. Further experiments were carried out to prove the speci?c recognition of target matter. In vitro study con?rmed that aptamer-functionalized hydrogels can be used as drug carriers in targeted therapy and in biotechnological applications.In the third chapter, we have employed the catalyst-free “tetrazole-alkene” photo-click chemistry to form an aptamer-functionalized peptide hydrogel. In the process of the synthesis, the great features of click chemistry such as high speci?city and quantitative conversion have been inherited and the rapid and efficient synthesis is achieved without the catalyst. In this design, we have used the peptide as the backbone in the hydrogel, which could ensure the biocompatible and biodegradable of the hydrogels. The aptamer, which was crosslinked in the hydrogel, could realize the targeted drug release of the hydrogel. Also, the pyrazoline cycloadducts had strong fluorescence with variable emissions in the region of 487-538 nm, which could be used in the tracer method. The hydrogels hold tremendous potentials in the field of drug carrier, biological medicine, and drug release.