Rational design and implementation of a cucurbit[8]uril-based indicator-displacement assay for application in blood serum

Abstract

In this study, we report the first supramolecular indicator displacement assay (IDA) based on cucurbit[n]uril (CBn) host and a [2.2]paracyclophane derivative as indicator that is operational in blood serum.

Teaching indicators to unravel the kinetic features of host–guest inclusion complexes

“…Fig. 3a shows the kinGDA traces that were obtained when the ultra-high-affinity dye MPCP 33 was added to a solution of spectroscopically silent CB8*nandrolone complex. During the re-equilibration, nandrolone leaves the CB8 cavity, making room for the inclusion of indicator dye MPCP, which is the stronger binding guest.…”

Covalent cucurbit[7]uril–dye conjugates for sensing in aqueous saline media and biofluids

“…73 Dilution-stable unimolecular CBn-dye conjugates are attractive chemosensors for diagnostics applications in biouids because cucurbit[n]uril macrocycles (CBn, n ¼ 5-8, 10, 12), especially CB7, show high binding affinities for several biologically relevant molecules in aqueous media such as amino acids and their derivatives, peptides, and drugs. 11,[14][15][16]21,[74][75][76] Amantadine, which is a common drug to treat type A inuenza viruses 77 and dyskinesia associated with Parkinson's disease, [78][79][80] is strongly bound to CB7 with affinities up to 10 12 M À1 . 58 In the particular case of amantadine, the line between curing treatment and the occurrence of a series of side effects due to the accumulation of amantadine in the human body is narrow.…”

“…19,20 We recently demonstrated that the use of a high-affinity dye for CB8 enabled the detection of the drug memantine in blood serum by IDA. 21 However, this approach can have severe fundamental limitations, e.g. for CB7-based assays, that are discussed further below.…”

Kinetics and Mechanism of Cation‐Induced Guest Release from Cucurbit[7]uril

“…[1] They have acontinuously expanding range of applications in the biomedicine, [2] drug delivery, [3] catalysis [4] and sensing. [5] The nonpolar,l ow-polarisability CBn cavity readily includes hydrophobic moieties, whereas the high electron density of the carbonyl-laced portals facilitates the interaction with cations. Thee lectrostatic and hydrophobic effects combined with the complementary dimensions of CBn interior and guests leads to particularly strong binding of cationic organic compounds.…”

“…It is known for CB n host–guest complexes that the apparent binding constant of guest encapsulation is reduced in the presence of inorganic salts, but it is unknown to what extent this effect arises from competitive binding of M n + to form CB n –M n + complexes or from the formation of less‐stable guest–CB n –M n + ternary complexes. Although it is difficult to obtain such mechanistic insights by affinity measurements, we show here that these two scenarios can be easily distinguished by kinetic studies.…”