Q: Could you explain the significance of your article to the non-specialist?

A: Firstly, due to the fluid character of the water/oil interface, stepwise interfacial self-assembly allows generation of macroscopic nanoparticle multilayered films with few defects. Secondly, due to the Janus-faced character of the interface, the interface self-assembly allows assembly of both aqueous and organic nanoparticles together, combining the advantages of both aqueous and organic synthesis methodologies. Thirdly, due to the well-established chemistry of DNA-bases, the DNA specific pairing allows flexible alteration of the surface functionality of the nanoparticles attached at the interface. Fourthly, multiple hydrogen bonding between DNA bases can cross-link the resulting films to form mechanically robust freestanding films.

Q: What has motivated you to conduct this work?

A: This work is an extension of our current success on directing nanoparticles to selfassemble at the water/oil interface. The recognition of the Janus-faced character of the interface between water and oil inspired us to conduct phase-selective surface modification of the nanoparticles attached at the interfaces and consecutively absorb other aqueous and organic nanoparticles into the interface.

Q: Where do you see this work developing in the future?

A: Of particular interest is to construct multilayered freestanding films of different nanoparticles to create a vectorial transfer of charge or energy across the film, which should not only lead to advanced thin film devices but shed light on fundamental issues associated with interface physics such as the structure of water surrounding nanoparticles attached at the water/oil interface and the surface charge of the particles in the oil side. It is also worthy to pursue to use of stimuli-responsive spacers, either ligands or nanoparticles, to manipulate the charge transfer across the nanoparticle films.

Q: Are there any particular challenges facing future research in this area?

A: Due to the exceedingly tiny dimension of the nanoparticles, it is a formidable challenge to determine the multilayered structure of nanoparticle films structures at the water/oil interface. This task should be inevitable in future, though. Furthermore, analyzing the distribution of the ligands modified on the surfaces of the nanoparticles attached at the water/oil interfaces is also beyond the capability of our current experimental facilities.