Conjugated Polymeric Nanostructures as Potential Tools in DNA Nanotechnology: Interactions with the Double Helix

We synthesized two types of conjugated polymeric nanoparticles (CPNs), made with MEH-PPV (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]) and PFD (poly(9,9-di-n-dodecyl fluorenyl-2,7-diyl)), that significantly interact with double-stranded DNA. The binding between these nanostructures and the biopolymer was characterized via single-molecule force spectroscopy assays performed by optical tweezers and by direct visualization via atomic force microscopy imaging. The results show that both types of CPNs bind cooperatively outside the double helix, inducing bending, and with a considerably high equilibrium association constant, on the order of 106 M–1. We thus demonstrate that conjugated polymeric nanostructures can strongly and cooperatively interact with double-stranded DNA using single-molecule force spectroscopy. These interactions may represent promising long-term perspectives for applications in DNA nanotechnology and functional nanomaterials, such as the design of DNA-based nanodevices and the development of new drug carriers based on functionalized nanoparticles for cancer chemotherapies, to cite a few.