The Design Of Bioorthogonal Copper Click Reaction Catalyst And Its Bioapplications

Bioorthogonal reaction is a class of chemical reactions that occurs rapidly and specifically in mild physiological environments.The reaction does not interfere with the inherent biochemical process,causes no damage to the organism and target biomolecules.Its high selectivity and efficiency make it a powerful method for biological and biomedical monitoring and regulation of biological systems.As a typical bioorthogonal reaction,click reaction has attracted more and more attention in the field of biomedical and nanomedicine engineering.Cu-catalyzed azide-alkyne cycloaddition(CuAAC)is one of the most widely used click chemical reactions.At present,CuAAC reaction is not only successfully applied to the in vitro and in vivo labeling and tracking of biological molecules such as proteins,polysaccharides and nucleic acids,but also a powerful tool for prodrug activation or in situ synthesis of drugs,such as anti-tumor,anti-bacterial and anti-spasmodic drugs.Efficient bioorthogonal click reaction is of great significance to the study of biological dynamic processes.CuAAC reaction has the outstanding advantages of fast reaction speed and reproducible experimental results under physiological conditions,which has attracted the attention of researchers and further study.However,the inherent toxicity of Cu(I)and the low catalytic activity of existing zero-valent copper nanoparticles(CuNPs)greatly limit its further bioapplications.In this paper,a series of highly efficient heterogeneous CuNPs catalysts were synthesized to study their reaction efficiency in the process of catalyzing CuAAC reaction,and to verify that the catalytic process of these catalysts in different cells to achieve in situ drug synthesis and ultimate tumor treatment.The achievements are summarized as follows:1.We have designed a mesoporous carbon supported CuNPs(MCNs-Cu)as a novel catalyst for bioorthogonal click reactions.The photodynamic activity of MCNs could induce the generation of ROS under NIR irradiation to promote the conversion of Cu(0)to Cu(I),thus catalytically boosting the CuAAC reaction.The photothermal effect of MCNs could also availably transform NIR light into heat to increase the local temperature(photothermal conversion efficiency,η=50.6%)and to promote the transformation of Cu(Ⅰ),further accelerating the catalytic efficiency and conversion rate.Photodynamic and photothermal effect synergistically promote Cu(1)conversion and CuAAC reaction rate,further achieving efficient CuAAC reaction.In addition,both in vitro and in vivo experiments demonstrated that MCNs-Cu had high catalytic performance under NIR light.With excellent catalytic ability and good biological safety,the NIR dual-promoted heterogeneous MCNs-Cu nanocatalyst would blaze a promising path for alternative bioorthogonal catalysis development.2.We have designed and constructed a DNA-based platform as a biocompatible,highly efficient,and precisely targeted bioorthogonal nanocatalyst.The resulting copper nanoparticles(CuNPs)have the advantages of small sizes,good dispersion,stability,and low toxicity to cells.Precise targeting is achieved by using different types of aptamers that recognize cancer cells.The introduction of DNA offers an attractive catalyst synthesis method.The platform can catalyze CuAAC reaction in vitro with short reaction time and high yield.The theoretical calculation further supports the contribution of DNA to the enhanced catalytic activity.More importantly,the work addresses the issues of the lack of precise targeting and inefficient catalytic activity of the bioorthogonal catalyst in living system.The highly efficient,targeted,and biocompatible nanocatalyst can be applied in tumor therapy via in situ activation of prodrugs.The precise and efficient catalytic synthesis of drugs in tumor tissues can ensure satisfactory and specific antitumor efficacy and reduce the serious adverse effects.Furthermore,the programmability of nucleic acids enables the generality of DNA-based nanocatalyst by simply using different sequences.In vivo tumor therapy demonstrates the safety and efficacy of the system in mammals.The work provides exciting opportunities to design versatile bioorthogonal catalysts for in vivo applications in complex multicellular organisms.3.We have constructed a DNAzyme-augmented and novel targeted bioorthogonal catalysis system.Using the high local concentration of H2O2 in cancer cells,the DNAzyme could produce active radical species to facilitate the conversion of Cu(0)to Cu(I)on the surface of DNA-templated untrasmall CuNPs,resulting in much enhanced bioorthogonal catalytic activity and enabling in situ prodrug activation.In addition,the aptamer AS 1411/hemin-based DNAzyme exhibited cancer cell-targeting ability through specific recognition of nucleolin overexpressed on the surface of cancer cells.Meanwhile,the cancer-killing radical species produced by DNAzyme could offer synergistic chemodynamic effect.The combination of in situ drug synthesis with chemodynamic therapy successfully achieved highly specific and efficient therapeutic efficacy with minimal side effects.The study offers a simple and novel avenue to develop high efficient and safe bioorthogonal catalysts for biological applications.