Regulation Of DNA Properties By Conjugated Polymer Nanoparticles

The conjugated polymer has a long-range delocalized?-electron structure,good light absorption capability,and signal amplification effect.In recent years,scientists have developed a series of conjugated polymers that absorb in the near-infrared region,which convert the absorbed near-infrared light energy into heat.In addition,in order to improve water solubility,conjugated polymers are usually prepared into nanoparticles,which are widely used for drug loading,fluorescence imaging,antibacterial,and carbon dioxide response because of their excellent dispersibility,biocompatibility,and photostability.Based on the development of conjugated polymer nanoparticles and carbon dioxide,the conjugated polymer nanoparticles were designed and studied,and their regulation of DNA properties was studied.(1)CPN_S with uniform distribution of maleimide groups on the surface was prepared by coprecipitation of DSPE-PEG₂₀₀₀-MAL with donor-acceptor(D-A)conjugated polymer(PD-8-DTTE-7) using 1,2-distearoyl-sn-glycero-3-phosphor-ethanol-amine-N-[maleimide(polyethyleneglycol)-2000](DSPE-PEG₂₀₀₀-MAL)as encapsulation matrix.2-Mercapto-1-methylimidazole exhibiting carbon dioxide response characteristics was grafted onto the shell to obtain imidazole-functionalized nanoparticles(Imidazole-CPNs).After reacting with carbon dioxide,the imidazole group is protonated,and the surface charge of the nanoparticles changes,thereby affecting the adsorption of ds DNA on the surface of imidazole-CPNs.At the same time,the microscopic morphology,diameter and surface charge are detedted by scanning electron microscopy,dynamic light scattering,and Zeta potential.(2)After the addition of carbon dioxide,the negatively charged DNA on the surface can be electrostatically adsorbed on the surface of the positively charged nanoparticles to form an imidazole-CPNs/DNA assembly,which could promotes the regulation of the unwinding of the double-stranded DNA by imidazole-CPNs under near-infrared light stimulation.The unwinding of DNA was detected by measuring changes in the fluorescence intensity of ethidium bromide EB,circular dichroism of DNA,and agarose gel electrophoresis.