Cucurbit[8]uril as Nanocontainer in a Polyelectrolyte Multilayer Film: A Quantitative and Kinetic Study of Guest Uptake

Abstract

The host-guest chemistry of cucurbit[8]uril (CB[8]) and the layer-by-layer self-assembly technique are combined to obtain a molecular imprinted polyelectrolyte multilayer film for the recognition and binding of a guest molecule. Cucurbit[8]uril as a ready-made binding site is first associated with a polyelectrolyte and then assembled into a polyelectrolyte multilayer film via layer-by-layer deposition. A cationic guest is subsequently included into the nanocontainer due to specific host-guest interactions. The quantitative analysis of both CB[8] and the included guest molecule in dependence of the surface charge of the multilayer film identifies a high nanocontainer density as well as good to excellent binding efficiencies, therefore yielding a promising imprinted nanomaterial with potential applications in filtration or sensor technology. The investigation of the guest molecule uptake kinetics reveals two processes on different time scales, respectively, which are again related to the charge of the multilayer film surface. The combination of the results obtained from both ultraviolet spectroscopy and dissipative quartz crystal microbalance enables us to describe a full picture of several simultaneous processes initiated by the guest molecule.

pH-Responsive Host–Guest Complexation in Pillar[6]arene-Containing Polyelectrolyte Multilayer Films

“…In conclusion, the WP6-containing multilayer films do not provide other sufficiently strong attractive interactions towards the guest, except of the desired hostguest interactions. This fact demonstrates a rare and outstanding property of these multilayer films compared to previous approaches, which were found to suffer from a decomposition of the binding sites, and moderate to enhanced unspecific binding of the guest due to secondary interactions [42,43,49,59]. Following this procedure over several samples, each undergoing ten pH-stimulated binding and release cycles, averaged data of Γ MV was obtained and is given in Figure 11 (green squares).…”

“…Taking our previous approaches employing cucurbituril into account [48,49,59,60], the CB[8]-based layer systems revealed a host coverage of 0.5 nmol cm −2 per bilayer, while classical SmiLbL films also yielded a binding site coverage of 0.1 nmol cm −2 per bilayer [40]. A potential explanation for the reduced host coverage of WP6 as compared to CB [8] might be the fact that WP6 was deposited as single molecule and without pre-association to a polyelectrolyte in order to reduce the content of non-binding and "inactive" material.…”

“…Therefore, the host-guest chemistry of CB [8] could be implemented in polyelectrolyte multilayer films and be able to perform the reversible binding and release of a guest molecule controlled by either redox-conditions [47] or light irradiation [48]. A quite high binding efficiency over several binding and release cycles was observed [49]. Furthermore, the initial imprinting step, realized via pre-complexation during preparation, was no longer required as a result of the ready-made character of CB [8] as artificial binding site.…”

Host-Guest Chemistry in Layer-by-Layer Assemblies Containing Calix[n]arenes and Cucurbit[n]urils: A Review

“…Thus, CB [8] is a promising synthetic glue, similar to binding proteins, such as avidin and lectin [72,73], for the construction of protein nano-assemblies. It is anticipated that CB[n]-containing LbL films will be suitable for use as scaffolds for the binding and release of small molecules by taking advantage of the binding ability of CB[n]s. In this context, LbL films have been prepared by the alternate deposition of PAA and a cationic polymer bearing viologen side chains complexed with CB [8] [74]. The LbL films thus prepared were able to bind anthracene-substituted pyridinium bromide (AnPy), which formed charge-transfer complexes with the viologen moiety in the cavity of CB [8] in the film.…”

Stimuli‐Responsive Cucurbit[n]uril‐Mediated Host‐Guest Complexes on Surfaces

“…[83] This type of multilayer films with imprints has potential for sensing platforms or nanomaterials, since they can mimic complicated molecular recognition systems in nature (Figure 5c). Usual multilayer films can lose their shape and stability over time, however the multilayer films containing CB [8] were found to be more rigid and had specific recognition properties.…”