• bivalent stopper
• CB[8]-nanoparticles
• supramolecular nanoparticles
• valency effects

Supramolecular materials hold great promise as they allow the development of a versatile toolbox combined with properties such as responsiveness, exchange, uptake and delivery, size control, and many others. Supramolecular nanoparticles (SNPs) are of huge interest because of their high potential for biomedical applications, for example as in-vivo imaging and drug delivery vehicles. Here, SNPs based on the ternary-complex formation among cucurbit[8]uril (CB[8]), a methyl viologen polyethylene imine (MV-PEI) and novel multivalent naphthol-functionalized moieties, were assembled and the influence of the multivalency over the size-tunability was studied.
A bivalent PEG-based stopper and a more intense grafted PAMAM dendrimer, named Np2-PEG and Np16-PAMAM, were synthesized, functionalized with the naphthol moieties and then separately employed as recognition units in the nanoparticles self-assembling. The effects of their greater valency over the SNPs size-tunability were investigated through Dynamic Light Scattering (DLS) and Scanning Electron Microscopy (SEM). Particles assembled with the bivalent stopper revealed that the increased valency of the stopper induces the formation of more stable ternary complexes. Hence, the dynamic disassembly and reassembly processes, required for the formation of well-defined and size-tunable SNPs, are disfavored unless the temperature increases and well-defined nanoparticles are shaped. In contrast, the studies about the increased valency in the core of the nanoparticles showed that by respecting the 1:1:1 ratio among MV2+:CB[8]:Np-PEG/Np16-PAMAM, required for the formation of the ternary complex, the amount of the stopper is not enough to control the intermolecular network formation caused by the more intense grafted dendrimer. However, a control over the size of the SNPs was possible when the ratio among the supramolecular recognition units was changed from the traditional 1:1:1 to the newly 1:1:1:X, where X represents the amount of Np16-PAMAM.