Antibacterial And Imaging Research Based On Conjugated Polyfluorene Ethylene Compound Nanoparticles

Bacterial infection is one of the major factors that threaten human health.The emergence of antibiotics has undoubtedly made a tremendous contribution to the treatment of bacterial infections.However,with the overuse of antibiotics in recent years,bacteria have a certain resistance to antibiotics,leading to the emergence of superbugs that seriously threatens human public health.Therefore,it is of great significance to develop new antibacterial agents and antibacterial methods that are not affected by bacterial resistance.Recently,the antimicrobial nanomaterials attracted more and more attention,due to its advantages of small size and large specific surface area,it greatly enhances antibacterial activity.At present,although common metal oxide nanoparticles,heavy metal nanoparticles,and carbon nanotubes have good antibacterial activity,there are drawbacks such as requiring photocatalysis,high biological toxicity,and poor biocompatibility,which limit their biomedical applications.The conjugated polymers are macromolecular compounds with excellent photoelectric properties,and were widely applied in biological diagnosis and treatment.The cationic surfactant cetyltrimethylammonium bromide(CTAB),an amphiphilic compound with a quaternary ammonium group,is commonly used as a solubilizer and antibacterial agent.However,high concentrations are required to achieve the desired antibacterial effect.In this paper,a novel conjugated polymer nanoparticle CA-CPNs was designed and synthesized based on conjugated polymers PFVBT and CTAB.The PFVBT forms the core by hydrophobic interaction,and the CTAB is introduced during the reprecipitation process to form a shell on the surface of the nanoparticle.Thus the nanoparticle is positively charged.After incubating with bacter:ia,CA-CPNs exhibits high affinity toward bacteria through electrostatic interactions.Then nanoparticles diffuse through the cell wall and disrupt cytoplasmic membrane,leading to the bacteria death upon release of the cytoplasmic constituents of the cell.The nanoparticles do not require light or chemical energy as the power.When 0.8 ?g/mL and 1.0 ?g/mL CA-CPNs were incubated for 30 min with E.coli and S.aureus,respectively,more than 90%of bacteria were dead.Also,the antibacterial activities are higher than of CTAB at the same concentration,its performance is superior to that of most nanoparticles based on photodynamic therapy at present.Furthermore,the cell viability assay showed that CA-CPNs have good biocompatibility,low cytotoxicity,and certain phototoxicity,indicating that they are potential for antitumor treatment.Because of the bright red fluorescence of CA-CPNs,the nanoparticles were successfully applied to image the live cell of MCF-7.It can be observed that CA-CPNs enter the cell nucleus for fluorescence imaging.In summary,we designed and synthesized multifunctional CA-CPNs,which not only exhibit broad-spectrum and highly efficient antibacterial activity in the dark,but also successfully achieved fluorescence imaging in living cells.Furthermore,it is has potential for antitumor treatment.