Monomeric Cryptophane with Record-High Xe Affinity Gives Insights into Aggregation-Dependent Sensing

Cryptophane host molecules provide ultrasensitive contrast agents for 129Xe NMR/MRI. To investigate key features of cryptophane-Xe sensing behavior, we designed a novel water-soluble cryptophane with a pendant hydrophobic adamantyl moiety, which has good affinity for a model receptor, beta-cyclodextrin (β-CD). Adamantyl-functionalized cryptophane-A (AFCA) was synthesized and characterized for Xe affinity, 129Xe NMR signal, and aggregation state at varying AFCA and β-CD concentrations. The Xe-AFCA association constant was determined by fluorescence quenching, KA = 114,000 ± 5000 M-1 at 293 K, which is the highest reported affinity for a cryptophane host in phosphate-buffered saline (pH 7.2). No hyperpolarized (hp) 129Xe NMR peak corresponding to AFCA-bound Xe was directly observed at high (100 μM) AFCA concentration, where small cryptophane aggregates were observed, and was only detected at low (15 μM) AFCA concentration, where the sensor remained fully monomeric in solution. Additionally, we observed no change in the chemical shift of AFCA-encapsulated 129Xe after β-CD binding to the adamantyl moiety and a concomitant lack of change in the size distribution of the complex, suggesting that a change in the aggregation state is necessary to elicit a 129Xe NMR chemical shift in cryptophane-based sensing. These results aid in further elucidating the recently discovered aggregation phenomenon, highlight limitations of cryptophane-based Xe sensing, and offer insights into the design of monomeric, high-affinity Xe sensors.

Medienart:

E-Artikel

Erscheinungsjahr:

2021

Erschienen:

2021

Enthalten in:

Zur Gesamtaufnahme - volume:93

Enthalten in:

Analytical chemistry - 93(2021), 3 vom: 26. Jan., Seite 1507-1514

Sprache:

Englisch

Beteiligte Personen:

Zemerov, Serge D [VerfasserIn]
Lin, Yannan [VerfasserIn]
Dmochowski, Ivan J [VerfasserIn]

Links:

Volltext

Themen:

3H3U766W84
Beta-Cyclodextrins
Betadex
Cryptophane A
JV039JZZ3A
Journal Article
Polycyclic Compounds
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Xenon
Xenon Isotopes

Anmerkungen:

Date Completed 18.02.2021

Date Revised 27.01.2022

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1021/acs.analchem.0c03776

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM319205614