title: Depolarization Laplace transform analysis of exchangeable hyperpolarized ¹²⁹Xe for detecting ordering phases and cholesterol content of biomembrane models.
abstract: We present a highly sensitive nuclear-magnetic resonance technique to study membrane dynamics that combines the temporary encapsulation of spin-hyperpolarized xenon ((129)Xe) atoms in cryptophane-A-monoacid (CrAma) and their indirect detection through chemical exchange saturation transfer. Radiofrequency-labeled Xe@CrAma complexes exhibit characteristic differences in chemical exchange saturation transfer-driven depolarization when interacting with binary membrane models composed of different molecular ratios of DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) and POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine). The method is also applied to mixtures of cholesterol and POPC. The existence of domains that fluctuate in cluster size in DPPC/POPC models at a high (75-98%) DPPC content induces up to a fivefold increase in spin depolarization time τ at 297 K. In POPC/cholesterol model membranes, the parameter τ depends linearly on the cholesterol content at 310 K and allows us to determine the cholesterol content with an accuracy of at least 5%.
authors.affiliation: European Research Council Project BiosensorImaging, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Schnurr
authors.affiliation: European Research Council Project BiosensorImaging, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Witte
authors.affiliation: European Research Council Project BiosensorImaging, Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany. Electronic address: lschroeder@fmp-berlin.de.
authors.forename: Leif
authors.initials: L
authors.lastname: Schröder
mesh_terms: D002784:Cholesterol / Q000032:analysis*; D008051:Lipid Bilayers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011083:Polycyclic Compounds / Q000737:chemistry; D014979:Xenon Isotopes / Q000737:chemistry
chemical_list: D008051:Lipid Bilayers; D011083:Polycyclic Compounds; D014979:Xenon Isotopes; C545484:cryptophane A; D002784:Cholesterol