Application Of Organic Conjugated Molecular System In Photodynamic Therapy And Cell Imaging

Conjugated polymers and small organic conjugated molecules have been widely used in the field of optoelectronics and biomedicine because they have excellent optoelectronic properties and fluorescence amplification effects.In recent years,the application of organic conjugated molecule systems in disease diagnosis,imaging and photodynamic therapy has become a research focus.Photodynamic therapy(PDT),as a new treatment method,possesses characteristics including mild trauma,low toxicity,less side effects,rapid sterilization and avoidance of drug resistance of pathogenic bacteria.Based on the above background,we design and prepare nanomaterials for fluorescence imaging and photodynamic therapy.The nanomaterials combines the properties of organic conjugated molecule systems and photodynamic therapy.The main research contents are as follows:1.In this work,a conjugated polymer(PPV-M)is designed and synthesized to link quaternized N-methyl-imidazole groups as pendants which endow the polymer to bear positive charges and enhance water solubility.PPV-M could bind to pathogenic microorganisms with negative surface charge by the electrostatically.To research the PPV-M on photodynamic bactericidal efficacy,E.coli,S.aureus and C.albicans were selected as representatives.Laser confocal scanning microscopy(CLSM)and zeta potential characterizations indicate that PPV-M can select bind bacteria but not adsorp to fungi,and has high bactericidal activity against E.coli and S.aureus.2.The homopolymeric conjugated polymer PPV was designed and synthesized,and its side chain was water-soluble modified.By UV absorption spectroscopy and fluorescence emission spectroscopy characterizations,the PPV displays a large Stokes shift of 102 nm which could effectively prevent the self-absorption of fluorescence.PPV-M exhibits the same excellent properties and is beneficial to cell fluorescence imaging.Cytotoxicity assays indicate the PPV and PPV-M did not show significant toxicity to cells in the range of fluorescence imaging concentrations.By the colocalization experiment,PPV and PPV-M have specific imaging ability for lysosomes,and have better light stability and long-term imaging ability than commercial dyes.3.Nanoparticles were prepared using small organic fluorescent conjugated molecules and an amphiphilic polystyrene maleic anhydride(PSMA).The nanoparticles can be uniformly dispersed in an aqueous solution.The nanoparticles can be sensitized to produce reactive oxygen species under light irradiation condition.The isothermal titration microcalorimetry characterization indicates that the nanoparticles have strong bindingability to bacteria,and the nanoparticles exhibit good photodynamic bactericidal activity.