Optical detection of aqueous phase analytes via host-guest interactions on a lipid membrane surface

The organization and assembly of molecules in cellular membranes is orchestrated through the recognition and binding of specific chemical signals. A simplified version of the cellular membrane system has been developed using a synthetically prepared membrane receptor incorporated into a biologically derived lipid bilayer. Through an interplay of electrostatic and van der Waals interactions, aggregation or dispersion of molecular components could be executed on command using a specific chemical signal. A pyrene fluorophore was used as an optical probe to monitor the aggregational state of the membrane receptors in the bilayer matrix. The pyrene excimer emission to monomer emission (E/M) intensity ratio gave a relative assessment of the local concentration of receptors in the membrane. Bilayers were prepared with receptors selective for the divalent metal ions of copper, mercury, and lead. Addition of the metal ions produced a rapid dispersion of aggregated receptor components at nano- to micro-molar concentrations. The process was reversible by sequestering the metal ions with EDTA. Receptors for proteins and polyhistidine were also prepared and incorporated into phosphatidylcholine lipid bilayers. In this case, the guest molecules bound to the membrane through multiple points of interaction causing aggregation of initially dispersed receptor molecules. The rapid, selective, and sensitive fluorescence optical response of these lipid assemblies make them attractive in sensor applications for aqueous phase metal ions and polypeptides.

[1]  H. Galla,et al.  Excimer-forming lipids in membrane research. , 1980, Chemistry and physics of lipids.

[2]  Frances H. Arnold,et al.  METAL-INDUCED DISPERSION OF LIPID AGGREGATES : A SIMPLE, SELECTIVE, AND SENSITIVE FLUORESCENT METAL ION SENSOR , 1995 .

[3]  Darryl Y. Sasaki,et al.  DITHIOAMIDE METAL ION RECEPTORS ON FLUORESCENT LIPID BILAYERS FOR THE SELECTIVE OPTICAL DETECTION OF MERCURIC ION , 1998 .

[4]  D. Lasič,et al.  Liposomes: From Physics to Applications , 1993 .

[5]  Markus Lerchi,et al.  Lead-selective bulk optodes based on neutral ionophores with subnanomolar detection limits , 1992 .

[6]  G. Gaines,et al.  Insoluble Monolayers at Liquid-gas Interfaces , 1966 .

[7]  Klaus Eichmann,et al.  Transmembrane Signaling of T Lymphocytes by Ligand‐Induced Receptor Complex Assembly , 1993 .

[8]  Frances H. Arnold,et al.  Specific Protein Attachment to Artificial Membranes via Coordination to Lipid-Bound Copper(II) , 1994 .

[9]  A. Ulmann,et al.  An introduction to ultrathin organic films , 1991 .

[10]  Kenneth M. Yamada,et al.  Synergistic roles for receptor occupancy and aggregation in integrin transmembrane function , 1995, Science.

[11]  B. Seaton,et al.  Effect of vesicle composition and curvature on the dissociation of phosphatidic acid in small unilamellar vesicles--a 31P-NMR study. , 1994, Biochimica et biophysica acta.

[12]  Frances H. Arnold,et al.  Engineering protein-lipid interactions : targeting of histidine-tagged proteins to metal-chelating lipid monolayers , 1995 .

[13]  F. Arnold,et al.  Fluorescence signaling of ligand binding and assembly in metal-chelating lipid membranes. , 1996, Chemistry & biology.