Self-assembly of size-tunable supramolecular nanoparticle clusters in a microfluidic channel

Supramolecular nanoparticle clusters (SNPCs) have been formed in a microfluidic device by controlling the diffusive mixing of the constituting supramolecular building blocks. Cluster formation between ligand-functionalized silica nanoparticles, dendrimers, and poly(ethylene glycol) (PEG) stopper molecules is induced by the ternary charge-transfer complex formation between cucurbit[8]uril, methyl viologen and naphthol. The resulting SNPC size depends strongly on the stoichiometry of the host and guest binding partners, the competition between multivalent and monovalent naphthol entities, and the microfluidic flow conditions. Variation of the PEG length leads to modulation of its diffusion rate and thus to an additional kinetic control parameter of the SNPC formation process.