title: Mesophase in a thiolate-containing diacyl phospholipid self-assembled monolayer.
abstract: Maintaining the intrinsic features of mesophases is critically important when employing phospholipid self-assemblies to mimic biomembranes. Inorganic solid surfaces provide platforms to support, guide, and analyze organic self-assemblies but impose upon them a tendency to form well-ordered phases not often found in biomembranes. To address this, we measured mesophase formation in a thiolate self-assembled monolayer (SAM) of diacyl phospholipid, 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol (DPPTE) on Au(111), and provide thermodynamic analysis on the mixing behavior of inequivalent DPPTE acyl chains. Our work has uncovered three fundamental issues that enable mesophase formation: (1) Elimination of templating effects of the solid surface, (2) Weakening intermolecular and molecule-substrate interactions in adsorbates, and (3) Equilibrium through entropy-driven self-assembly. Thus, our work provides a more holistic understanding of phase behavior, from liquid phases to mesophases to highly crystalline phases, in organic self-assemblies on solid surfaces, which may extend their applications in nanodevices and to the wider fields of biology and medicine.
authors.affiliation: †Department of Urology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, Illinois 60611, United States.|§Simpson Querrey Institute for BioNanotechnology, Northwestern University, 303 East Superior, Chicago, Illinois 60611, United States.|#Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan 430068, China.
authors.forename: Wangqiang
authors.initials: W
authors.lastname: Sun
authors.affiliation: ∥Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States.
authors.forename: Sumit
authors.initials: S
authors.lastname: Kewalramani
authors.affiliation: ∥Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States.
authors.forename: Karl
authors.initials: K
authors.lastname: Hujsak
authors.affiliation: †Department of Urology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, Illinois 60611, United States.|§Simpson Querrey Institute for BioNanotechnology, Northwestern University, 303 East Superior, Chicago, Illinois 60611, United States.
authors.forename: Heng
authors.initials: H
authors.lastname: Zhang
authors.affiliation: ∥Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States.|⊥Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bedzyk
authors.affiliation: ∥Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States.
authors.forename: Vinayak P
authors.initials: VP
authors.lastname: Dravid
authors.affiliation: †Department of Urology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, Illinois 60611, United States.|§Simpson Querrey Institute for BioNanotechnology, Northwestern University, 303 East Superior, Chicago, Illinois 60611, United States.
authors.forename: C Shad
authors.initials: CS
authors.lastname: Thaxton
mesh_terms: D006046:Gold / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D044367:Phase Transition; D013499:Surface Properties; D014280:Triglycerides / Q000737:chemistry*
chemical_list: C520656:1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol; D014280:Triglycerides; D006046:Gold