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Recent study evidences the influence of shape complementarity and specific interactions on colloidal lock-and-key self-assembly


Confocal micrographs of the lock-and-key self-assembly into colloidal molecules with thermo-responsive valence. Scale bars: 1um.

So-called lock-and-key interactions, i. e., the preferred association of molecular building blocks with complementary shapes, are omnipresent in biology, where they for example describe the interactions between enzymes and their substrates. They are also providing the basis for the formation of well-defined molecular complexes using supramolecular chemistry. This approach from the molecular world has now been successfully transferred to the colloidal domain, i.e. to much larger synthetic particles with complementary shapes.

Scientists at the Divisions of Physical Chemistry and Theoretical Chemistry at Lund University have investigated the association between oppositely charged thermos-responsive synthetic lock and key particles. Supported by model calculations, the experiments demonstrate the high specificity of the assembly highlighted by the formation of defined clusters, so-called colloidal molecules. The lock and key particles exhibit temperature-dependent changes in size and conformation that allowed the researchers to reversibly tune the ‘valence’ of the colloidal molecules (see illustration). This reversible temperature-responsive dynamic self-association process can be seen as the colloidal analogue of adaptive chemistry. The emerging assembly rules could provide new routes to the creation of higher order hierarchical structures, which can be reversibly controlled by external stimuli. 

The work has been published in Science Advances.