title: Self-assembly of lipopolysaccharide layers on allantoin crystals.
abstract: Self-assembly of lipopolysaccharides (LPS) on solid surfaces is important for the study of bacterial membranes, but has not been possible due to technical difficulties and the lack of suitable solid supports. Recently we found that crystals of the natural compound allantoin selectively bind pure LPS with sub-nanomolar affinity. The physicochemical origins of this selectivity and the adsorption mode of LPS on allantoin crystals remain, however, unknown. In this study we present evidence that LPS adsorption on allantoin crystals is initiated through hydrogen-bond attachment of hydrophilic LPS regions. Hydrophobic interactions between alkyl chains of adjacently adsorbed LPS molecules subsequently promote self-assembly of LPS layers. The essential role of hydrogen-bond interactions is corroborated by our finding that allantoin crystals bind to practically any hydrophilic surface chemistry. Binding contributions of hydrophobic interactions between LPS alkyl chains are evidenced by the endothermic nature of the adsorption process and explain why the binding affinity for LPS is several orders of magnitude higher than for proteins (lysozyme, BSA and IgG) and polysaccharides. Self-assembly of LPS layers via hydrogen-bond attachment on allantoin crystals emerges as a novel binding mechanism and could be considered as a practical method for preparing biomimetic membranes on a solid support.
authors.affiliation: Bioprocessing Technology Institute, A*STAR (Agency for Science, Technology and Research), 20 Biopolis Way #06-01 Centros, Singapore 138668, Singapore. Electronic address: Vincent_Vagenende@bti.a-star.edu.sg.
authors.forename: Vincent
authors.initials: V
authors.lastname: Vagenende
authors.affiliation: Bioprocessing Technology Institute, A*STAR (Agency for Science, Technology and Research), 20 Biopolis Way #06-01 Centros, Singapore 138668, Singapore.
authors.forename: Tim-Jang
authors.initials: TJ
authors.lastname: Ching
authors.affiliation: Bioprocessing Technology Institute, A*STAR (Agency for Science, Technology and Research), 20 Biopolis Way #06-01 Centros, Singapore 138668, Singapore.
authors.forename: Rui-Jing
authors.initials: RJ
authors.lastname: Chua
authors.affiliation: Bioprocessing Technology Institute, A*STAR (Agency for Science, Technology and Research), 20 Biopolis Way #06-01 Centros, Singapore 138668, Singapore.
authors.forename: Qiu Zhen
authors.initials: QZ
authors.lastname: Jiang
authors.affiliation: Bioprocessing Technology Institute, A*STAR (Agency for Science, Technology and Research), 20 Biopolis Way #06-01 Centros, Singapore 138668, Singapore.
authors.forename: Pete
authors.initials: P
authors.lastname: Gagnon
mesh_terms: D000327:Adsorption; D000481:Allantoin / Q000737:chemistry*; D000818:Animals; D016466:CHO Cells; D002522:Chlorocebus aethiops; D003412:Cricetulus; D003460:Crystallization; D003911:Dextrans / Q000737:chemistry; D008050:Lipid A / Q000378:metabolism; D008070:Lipopolysaccharides / Q000737:chemistry* / Q000378:metabolism; D009113:Muramidase / Q000378:metabolism; D053758:Nanoparticles / Q000737:chemistry; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013499:Surface Properties; D013696:Temperature
chemical_list: D003911:Dextrans; D008050:Lipid A; D008070:Lipopolysaccharides; D012710:Serum Albumin, Bovine; D000481:Allantoin; D009113:Muramidase
keywords: Allantoin; Endotoxins; Hydrogen-bonding; Lipopolysaccharides; Self-assembled monolayer (SAM); Solid-supported lipid bilayer (SLB)