Binding studies of cucurbit[7]uril with gold nanoparticles bearing different surface functionalities

Abstract

Host-guest interactions between a synthetic receptor, cucurbit[7]uril (CB[7]), and gold nanoparticles (AuNPs) have been quantified using isothermal titration calorimetry. AuNPs were functionalized with ligands containing tertiary or quaternary benzylamine derivatives, with electron donating or withdrawing groups at the para position of the benzene ring. Analysis of binding interactions reveals that functional groups at the para position have no significant effect on binding constant. However, headgroups bearing a permanent positive charge increased the binding of AuNPs to CB[7] ten-fold compared to monomethyl counterparts.

Regulating Host–Guest Interactions between Cucurbit[7]uril and Guests on Gold Surfaces for Rational Engineering of Gold Nanoparticles

“…However, it was slightly stronger than when CB[7] was attached to the gold nanospheres. We also noticed that, in our case, the binding constant of 1 and CB[7] is 3 orders of magnitude higher than that of a similar guest and CB[7] reported by Rotello and co-workers . The large difference can be attributed to our use of pure water instead of salt buffer to avoid the competition binding from cationic ions …”

“…Most of the host–guest interactions with nanoparticles can be classified into four groups: (1) free host and free guest in the solution; (2) immobilized host and free guest; (3) free host and immobilized guest; (4) immobilized host and immobilized guest (Figure , classified host–guest interactions in this study). Rotello and co-workers quantified the host–guest interactions of CB[7] and some guests with phenyl (attached to gold nanospheres, group III in our classification) by direct isothermal titration calorimetry (ITC) experiments . However, the binding constants of the selected guests are very close, and they did not determine the binding constants when CB[7] is attached to the gold nanospheres.…”

Solution NMR methods for structural and thermodynamic investigation of nanoparticle adsorption equilibria

“…In particular, ITC was used to quantify the affinity of ligands towards the NP surface and guide the rational design of NP receptors with regulated binding strength towards specific targets. 142,143 In the drug-delivery field, ITC derived data are used to quantify the loading of active pharmaceutical ingredients on NP delivery vehicles. 144 In addition, ITC was reportedly used to characterize the thermodynamics of a few other ligand–NP systems.…”

Nanoparticle Probes for Quantifying Supramolecular Determinants of Biosurface Affinity

“…All the AuNPs used in this study have been synthesized and characterized in previous studies. [28,29,30,31,32] The octanol-water partition coefficients (LogP) of the terminal groups of AuNP surface ligands were estimated using ChemDraw Ultra 8.0.…”