Spontaneous assembly of phosphatidylcholine monolayers via chemisorption onto gold

Abstract

Phosphatidylcholine molecules bearing thiol and disulfide moieties at the terminus of both the sn-1 and sn-2 chains have been synthesized and chemisorbed onto freshly evaporated gold film. A combination of ellipsometry, contact angle measurements, heterogeneous electron-transfer properties, and X-ray photoelectron spectroscopy has shown that 1,2-bis (16-mercaptohexadecanoyl) -sn-glycero-3-phosphocholine and l,2-bis[12-(lipoyloxy)dodecanoyl]-sn-glycero-3-phosphocholine yield chemisorbed monolayers which are (i) densely packed, (ii) macroscopically uniform, (iii) strongly hydrophilic, and (iv) oriented such that the polar head groups extend outward from the surface and the sulfur moieties are in intimate contact with the gold. Ellipsometry and contact angle measurements indicate that analogous surfaces can be produced from l,2-bis(ll-mercaptoundecanoyl)-sn-glycero-3-phosphocholine and 1,2-bis[ 12-(isolipoyloxy)dodecanolyl]-sn-glycero-3-phosphocholine. The potential for adjusting and utilizing this new class of "biomembrane-like" surfaces for biochemistry, biology, and medicine is briefly discussed.

Is the Enhanced Adhesion of PEDOT Thin Films on Electrodes Due to Sulfur - Gold Interaction? - An XPS Study

“…A finding which is consistent throughout the literature is that covalent bonding to gold shifts the sulfur signal to lower binding energies, i.e. 161-162 eV, whereas unbound sulfur of organic molecules evokes a signal at 163-164 eV [13][14][15][16][17][18][19][20][21][22][23][24]. However, part of the signal at 163-164 eV may also originate from radiation damage due to extensive irradiation with X-rays [17].…”

“…As PEDOT contains a sulfur atom in every unit, and sulfur and gold are known to build strong self-assembled covalent bonds [11,12], the question arose of whether this thiol-gold chemistry is also found at the PEDOT-gold interface and could contribute to the mechanical stability of the coatings. While there is a vast number of studies on the interaction of thiols with gold [13][14][15][16][17][18][19], knowledge is limited with respect to thioethers such as thiophene or 3,4ethylenedioxythiophene (EDOT). For thiophene and its oligomers, somewhat contradictory results have been published.…”

Evidence of the Disassembly of α-Cyclodextrin-octylamine Inclusion Compounds Conjugated to Gold Nanoparticles via Thermal and Photothermal Effects

“…The peak with a lesser intensity, at 402.4 eV, is assigned to the nitrogen atom of the ammonium ion (-NH 3 + ) of the OA molecule (which is protonated, consistent with a pKa of 10.75 at pH 7). The peak with a higher intensity and lower binding energy, at 399.9 eV, is assigned to the -NH 2 groups that are adsorbed on the AuNPs, thereby increasing the electron density of the nitrogen atom [25,26,27,28]. Pong et al calculated the energy associated with the nitrogen interaction with different planes and ridges for the AuNPs, obtaining energies between 3.4 and 9.2 kcal/mol.…”

Determination of the physical structure of biological materials at biosensor interfaces by techniques of increasing magnification from microscopic to molecular scale

“…Various mediating reagents such as glutaraldehyde can be used to link biochemical species such as proteins to the free amine of APTES, which can be present in high density as a monolayer after initial derivatization of a surface. Surface deposition does not necessarily imply that covalent bonding is required, and new procedures such as selfassembly of thiol or disulphide terminated lipid, protein or polypeptide species on gold through sulphurgold interactions have generated much interest (Fabianowski et al, 1989). Techniques which rely on self-assembly or covalent deposition of protein or lipid layers tend to provide surfaces of variable density of coverage with numerous physical imperfections in the molecular packing.…”