Interaction of oligonucleotide-based amphiphilic block copolymers with cell membrane models

Oligonucleotides have unique molecular recognition properties, being involved in biological mechanisms such as cell-surface receptor recognition or gene silencing. For their use in human therapy for drug or gene delivery, the cell membrane remains a barrier, but this can be obviated by grafting a hydrophobic tail to the oligonucleotide. Here we demonstrate that two oligonucleotides, one consisting of 12 guanosine units (G12), and the other one consisting of five adenosine and seven guanosine (A5G7) units, when functionalized with poly(butadiene), namely PB–G12 and PB–A5G7, can be inserted into Langmuir monolayers of dipalmitoyl phosphatidyl choline (DPPC), which served as a cell membrane model. PB–G12 and PB–A5G7 were found to affect the DPPC monolayer even at high surface pressures. The effects from PB–G12 were consistently stronger, particularly in reducing the elasticity of the DPPC monolayers, which may have important biological implications. Multilayers of DPPC and nucleotide-based copolymers could be adsorbed onto solid supports, in the form of Y-type LB films, in which the molecular-level interaction led to lower energies in the vibrational spectra of the nucleotide-based copolymers. This successful deposition of solid films opens the way for devices to be produced which exploit the molecular recognition properties of the nucleotides.

Graphical abstractOligonucleotide-based block copolymer mixed with DPPC at the air–water interface to form thin films.Figure optionsDownload full-size imageDownload high-quality image (81 K)Download as PowerPoint slide