Design, Synthesis, Characterization And Biological Applications Of Zwitterion Water-soluble Conjugated Polymers

Water-soluble conjugated polymers are widely used in biological detection,analysis and bioimaging because of their excellent optical properties and water solubility of polyelectrolyte.At present,the water-soluble conjugated polymers used for bioimaging are mostly cationic functional groups,which are linked by the side chain of the ionic functional groups.The nanoparticles are easily adsorbed by non specific proteins when circulating in the body,thus affecting the enhanced osmotic retention effect in the tumor tissues,and the cell fluorescence is carried out.When it is like,there are some problems such as cell endocytosis,easy to be absorbed by cell membrane and so on.The amphoteric ion type water-soluble conjugated polymer is expected to effectively resist the adsorption of non specific proteins and improve the adsorption of materials by cell membrane due to the simultaneous attachment of anions and cations to the side chain,so as to achieve better tumor targeting and bioimaging results.On the other hand,two-photon absorption of red / near infrared emitting fluorescent materials is one of the most important directions in the field of biological imaging because of small optical damage,high signal noise and depth detection.Therefore,the design and synthesis of fluorene as an electron donor(D),doped electron acceptor(A)4,7-double(2-bromine-5-thienyl)-2,1,3-benzothiazoles,D-π-A-π-D type water-soluble conjugated polymer P1’’ and P2’’ with a bond as a bridging unit,realized two photon excitation,red / near infrared fluorescence.Shoot and explore its photophysical properties and biological applications.1.an amphoteric water-soluble conjugated polymer P1’’ was designed and synthesized by introducing ammonium root cations and carboxylic acid root anions to different side chains of water-soluble conjugated polymers respectively.P1’’ can be used as a proportional fluorescent probe to achieve red / near infrared fluorescence emission.Compared with a cationic water-soluble conjugated polymer with the same main chain structure,P1’’ has a very high stability and anti nonspecific protein adsorption performance in the biological environment,and shows a higher cell uptake rate and can be effectively improved.The problem of cell membrane adsorption during cell imaging.The quantum yield of singlet oxygen of P1 " 62.4%" is expected to be used as an excellent photosensitizer for photodynamic therapy of tumor cells.2.an amphoteric water-soluble conjugated polymer P2’’ was designed and synthesized by introducing ammonium and sulfonic anions into the same chain of water-soluble conjugated polymers.P2’’ can achieve red / near infrared fluorescence emission as well as P1’’;the structure of sulfonic acid betaine ensures that P2’’ is also very stable in every pH environment.Compared with P1’’,P2’’ has higher stability and anti nonspecific protein adsorption performance in biological environment,and shows higher cell uptake rate,thus achieving higher bioimaging efficiency.Similarly,the singlet oxygen quantum yield of P2’’ can reach 24.36%,and it is also expected to be used as an excellent photosensitizer for photodynamic therapy of tumor cells.