Reversible Morphology Tuning Of DNA-perylenebisdiimide Assemblies Through Host-guest Interaction

Smart DNA nanostructures that can undergo controllable and reversible morphology change in response to environmental stimuli have found potential application in several fields including nanomaterials and biomedicine.Most stimuli-responsive systems are composed of amphiphilic DNA block copolymers or amphiphilic DNA-Dendron hybrids.These amphiphilic DNA hybrids can self-assemble into various well-defined DNA nanostructures such as spherical micelles,cylindrical micelles,vesicles and lamellar nanostructures.All of them possess DNA sequences at the periphery and hydrophobic domain at the core.The unique structure can not only act as surface addressable templates to load other functional molecules on their surfaces through DNA hybridization but can also encapsulate hydrophobic drugs at their core.So far,the morphology tuning of DNA nanostructures is upon these external triggers,such as temperature,p H values,DNA hybridization or DNA selective enzymatic activity.However,rational design of DNA hybrids and versatile approaches for morphology control of assemblies are still consistently needed.Supramolecular host-guest chemistry has been applied to material science,life science and so on.Among the well-known host molecules,cucurbit[n]urils(CB[n]s)and cyclodextrins(CDs)are two kinds of fascinating macrocyclic hosts with their distinctive molecular recognition properties.CB[n]s can selectively recognize organic cations,metal ions and so on,while CDs prefer neutral molecules,proteins,et al.On the basis of their host-guest chemistry,CB[n]s and CDs have been used in construction of supramolecular functional materials such as stimulus responsive hydrogels and in bio-system to achieve the reversible control.Thus,is there any way to regulate the assembly morphology of DNA hybrids through host-guest interaction? So far,it has been reported that amphiphilic DNA hybrids are constructed based on host-guest interaction and the self-assembly behavior of the amphiphilic DNA hybrids is studied.However,there are few reports about the effect of such host-guest interaction on the assembled morphology of guest-modified DNA.Based on the previous work,two studies were carried out: firstly,hydrophobic perylenebisdiimide core with two of 1-propinyl modified quaternary ammonium groups(PDIs-1)were employed to conjugate with DNA sequence via Cu I catalyzed [3+2] azide–alkyne cycloaddition reaction to obtain DNA-PDIs-1 conjugates.The self-assembly behavior of DNA-PDIs-1 conjugates in anqueous solution was studied.Moreover,the effect of interaction between hydrophilic PDIs-1 and host CB[8] and CB[10] on the assembled morphology and the application were further invertigated.Secondly,the DNA-PDIs-2 conjugates were synthesized from hydrophobic PDIs-2 and DNA by half-solid phase synthesis.The self-assembly behavior of DNA-PDIs-2 conjugates in aqueous solution were preliminarily studied.And the effect of the host-guest interaction between PDIs-2 and cyclodextrin on the morphology of the assembly was initially explored.