polymeric liposomes—attempts to mimic biomembrane processes : h. ringsdorf, university of mainz,...

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343 Polymeric Liposomes--Attempts to Mimic Biomembrane Processes H. Ringsdorf, University of Mainz, Mainz, Federal Republic of Germany Macromolecular chemistry has become a mature science with all advantages and handicaps of a well-established scientific discipline: many heights have been conquered and the harvest is abundant, but adventures and the future might be elsewhere. Future polymer chemistry cannot be limited to repetitive improvement of already successful mass polymers, but should rather expand into neighbouring fields of materials science as well as life science where '°polymer thinking" might help to overcome difficulties. The contribution deals with the stabilization of membrane model systems (monolayers, black lipid membranes, vesicles) in general. The desired further biological functionalization of these stabilized polymeric membranes is possible via incorporation of proteins. Addition of natural lipids to polymerizable membranes and enzymatic degradation of the unpolymerized component after polymerization makes selective opening of otherwise stable compartments possible. Cell-cell recognition--of vital importance in immuno- logical reactions--can be mimicked with polymeric vesicles carrying sugar headgroups. Finally, attempts are made to unite biological specification of natural cells and toughness of polymerized membranes via cell-vesicle fusion. Reversibly Polymerized Liposomes Steven L. Regen, Lehigh University, Bethlehem, PA, U.S.A. Phospholipid bilayer vesicles are of considerable current interest as models for biomembranes, as carriers of drugs, and as devices for photochemical solar energy conversion. In this paper we describe two unique classes of synthetic vesicles which can be transformed into a polymerized state via oxidation and macrocyclic ring opening, respectively. These membranes are based on the thiol-bearing molecules, 1,2-bis(ll-mercaptoundecanoyl)-sn-glycero-3-phos- phocholine, 1,2-bis(16-mercaptohexadecanoyl)-sn-glycero-3-phosphocholine, 1,2-bis(2-mercaptohexadecanoyl)-sn- glycero-3-phosphocholine, as well as a macrocyclic disulfide derivative of the first of these. Two key features of these assemblies, which distinguish them from other forms of polymerized phospholipid vesicles, are that they can be depolymerized via mild chemical reduction and that they are potentially biodegradable. Published in J. Amer. Chem. Soc., 107 (1985) 42 and 5804. Design of Submicroscopic Polyaldehyde Monospheres for Biological Applications S. Margel, L. Marcus, H. Meshulam and E. Wiesel, Weizmann Institute of Science, Rehovot, Israel Monodisperse polyaldehyde microspheres, e.g., polyglutaraldehyde and polyacrolein microspheres were formed by polymerization of the monomers in the presence of an appropriate surfactant which has both steric and electrostatic stabilizing effects. The conditions and the mechanism for obtaining monodisperse systems were studied. The microspheres were prepared via several mechanisms, in various sizes and with designated physical and chemical properties. The reaction of these microspheres through their aldehyde groups with ligands containing various functional groups, e.g., amine, thiol and carboxylate, will be discussed. The effect of temperature and pH on these reactants will also be illustrated. The polyaldehyde microspheres with the desired properties were used for applications such as specific cell labeling and separation, cell culturing, affinity chromatography and specific hemoperfusion.

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Polymeric Liposomes--Attempts to Mimic Biomembrane Processes H. R i n g s d o r f , University of Mainz, Mainz, Federal Republic of Germany

Macromolecular chemistry has become a mature science with all advantages and handicaps of a well-established scientific discipline: many heights have been conquered and the harvest is abundant, but adventures and the future might be elsewhere. Future polymer chemistry cannot be limited to repetitive improvement of already successful mass polymers, but should rather expand into neighbouring fields of materials science as well as life science where '°polymer thinking" might help to overcome difficulties. The contribution deals with the stabilization of membrane model systems (monolayers, black lipid membranes, vesicles) in general. The desired further biological functionalization of these stabilized polymeric membranes is possible via incorporation of proteins. Addition of natural lipids to polymerizable membranes and enzymatic degradation of the unpolymerized component after polymerization makes selective opening of otherwise stable compartments possible. Cell-cell recognition--of vital importance in immuno- logical reactions--can be mimicked with polymeric vesicles carrying sugar headgroups. Finally, attempts are made to unite biological specification of natural cells and toughness of polymerized membranes via cell-vesicle fusion.

Reversibly Polymerized Liposomes Steven L. Regen , Lehigh University, Bethlehem, PA, U.S.A.

Phospholipid bilayer vesicles are of considerable current interest as models for biomembranes, as carriers of drugs, and as devices for photochemical solar energy conversion. In this paper we describe two unique classes of synthetic vesicles which can be transformed into a polymerized state via oxidation and macrocyclic ring opening, respectively. These membranes are based on the thiol-bearing molecules, 1,2-bis(ll-mercaptoundecanoyl)-sn-glycero-3-phos- phocholine, 1,2-bis(16-mercaptohexadecanoyl)-sn-glycero-3-phosphocholine, 1,2-bis(2-mercaptohexadecanoyl)-sn- glycero-3-phosphocholine, as well as a macrocyclic disulfide derivative of the first of these. Two key features of these assemblies, which distinguish them from other forms of polymerized phospholipid vesicles, are that they can be depolymerized via mild chemical reduction and that they are potentially biodegradable.

Published in J. Amer. Chem. Soc., 107 (1985) 42 and 5804.

Design of Submicroscopic Polyaldehyde Monospheres for Biological Applications S. Marge l , L. M a r c u s , H. M e s h u l a m a n d E. Wiese l , Weizmann Institute of Science, Rehovot, Israel

Monodisperse polyaldehyde microspheres, e.g., polyglutaraldehyde and polyacrolein microspheres were formed by polymerization of the monomers in the presence of an appropriate surfactant which has both steric and electrostatic stabilizing effects. The conditions and the mechanism for obtaining monodisperse systems were studied. The microspheres were prepared via several mechanisms, in various sizes and with designated physical and chemical properties. The reaction of these microspheres through their aldehyde groups with ligands containing various functional groups, e.g., amine, thiol and carboxylate, will be discussed. The effect of temperature and pH on these reactants will also be illustrated. The polyaldehyde microspheres with the desired properties were used for applications such as specific cell labeling and separation, cell culturing, affinity chromatography and specific hemoperfusion.