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PubMed2001

Protective humoral immunity induced by surface-associated material from Actinobacillus actinomycetemcomitans in mice.

The aim of the present study was to determine the role of antibodies specific to anti-surface-associated material from Actinobacillus actinomycetemcomitans (anti-SAM-Aa) in an infection induced by this periodontopathogen in mice. When SAM-Aa obtained by saline extraction of A. actinomycetemcomitans Y4 was separated on one-dimensional gel electrophoresis, this constituent contained antigen fragments with molecular weights ranging from 14000 to 79000. Immunoblot analysis revealed that increased antigen dose/immunization resulted in increased numbers of antigen epitopes recognized by serum antibodies of the immunized mice. Rapid healing of the primary lesions and high levels of specific IgG antibodies after challenge with live A. actinomycetemcomitans were seen in the immunized mice, especially at the highest-dose level of 100 microg/immunization. Transfer of SAM-Aa-immunized, but not the SAM-Aa-immunized and adsorbed, serum prior to challenge with live bacteria led to rapid healing of the lesions in the recipient mice. Increased phagocytosis of A. actinomycetemcomitans by murine macrophages (RAW264.7 cells) was observed when this periodontopathogen was opsonized by the SAM-Aa-immunized, but not SAM-Aa-immunized and adsorbed, serum. These results suggest that in mice, SAM-Aa antigens may induce protective antibodies by acting, at least, as an opsonin against challenge with live A. actinomycetemcomitans.

Aggregatibacter actinomycetemcomitans↗
PubMed2002

Arrays of self-assembled monolayers for studying inhibition of bacterial adhesion.

This paper describes a simple and convenient method for the rapid screening of potential inhibitors of bacterial adhesion and for the quantitative evaluation of the efficacy of the inhibitors using arrays of self-assembled monolayers (SAMs) of alkanethiolates on gold that are presented on a 96-well microtiter plate. The SAMs present mixtures of alpha-D-mannopyranoside (a ligand that promotes the adhesion of uropathogenic Escherichia coli by binding to the FimH proteins on the tip of type 1 pili), and tri(ethylene glycol) moieties (organic groups that resist nonspecific adsorption of proteins and cells). The SAMs provide surfaces for studies of adhesion of uropathogenic E. coli to specific ligands; they also provide excellent resistance to nonspecific adhesion. Using arrays of mannoside-presenting SAMs, inhibitors of bacterial adhesion were easily screened by observing the number of bacteria that adhered to the surface of the SAMs in the presence of inhibitor. The potency of the inhibitor was quantified by measuring the percentage of inhibition as a function of the concentration of the inhibitor. The properties of SAMs, when combined with the convenience and standardization of a microtiter plate, make arrays of SAMs a versatile tool that can be applied to high-throughput screening of inhibitors of bacterial, viral, and mammalian cell adhesion and of strongly binding ligands for proteins.

Bacterial Adhesion↗
PubMed2004

Palladium as a substrate for self-assembled monolayers used in biotechnology.

This paper describes self-assembled monolayers (SAMs) on palladium that resist the nonspecific adsorption of proteins and the adhesion of mammalian cells. These SAMs form when thin films of palladium are exposed to solutions of alkanethiol with the general structure HS(CH(2))(m)()(OCH(2)CH(2))(n)()OH (m = 2, 11; n = 3, 6, 7). Ellipsometry and surface plasmon resonance spectroscopy (using a palladium-on-gold substrate) showed that these SAMs resist adsorption of all proteins present in bovine serum. Microislands of SAMs of octadecanethiol on palladium allowed patterned adhesion and growth of mammalian cells (in a "sea" of oligo(ethyleneglycol)-terminated SAM). The oligo(ethyleneglycol)-terminated SAM resisted the invasion of cells for over four weeks under standard conditions of cell culture; similar SAMs on gold remained patterned for only two weeks.

3T3 Cells↗
PubMed2001

Self-assembled monolayers of 4-mercaptobiphenyls.

This Account focuses on our systematic studies of the formation and properties of self-assembled monolayers (SAMs) of 4-mercaptobiphenyls on gold surfaces. The key difference between alkanethiolate and biphenyl thiolate SAMs is the rigid pi-character of the latter. The pi-conjugation between the adsorbing thiolate and the substituent at the 4'-position results in a molecular dipole moment that affects the adsorption kinetics as well as the equilibrium structure of mixed SAMs. Due to the lack of conformational disorder in the assembling molecules, these SAMs can serve as stable molecularly engineered model surfaces. Infrared spectroscopy and scanning tunneling microscopy, as well as X-ray and helium diffraction studies, suggest that biphenyl moieties in the SAMs have small tilt angles with respect to the surfaces normal. Finally, the morphology of glycine crystals nucleated and grown on these SAM surfaces depends on the structure of the nucleating glycine layer, which, in turn, depends on the H-bonding of these molecules with the SAM surface.

Journal Article↗
PubMed2001

Glutamate 47 in 1-aminocyclopropane-1-carboxylate synthase is a major specificity determinant.

Glutamate 47 is conserved in 1-aminocyclopropane-1-carboxylate (ACC) synthases and is positioned near the sulfonium pole of (S,S)-S-adenosyl-L-methionine (SAM) in the modeled pyridoxal phosphate quinonoid complex with SAM. E47Q and E47D constructs of ACC synthase were made to investigate a putative ionic interaction between Glu47 and SAM. The k(cat)/K(m) values for the conversion of (S,S)-SAM to ACC and methylthioadenosine (MTA) are depressed 630- and 25-fold for the E47Q and E47D enzymes, respectively. The decreases in the specificity constants are due to reductions in k(cat) for both mutant enzymes, and a 5-fold increase in K(m) for the E47Q enzyme. Importantly, much smaller effects were observed for the kinetic parameters of reactions with the alternate substrates L-vinylglycine (L-VG) (deamination to form alpha-ketobutyrate and ammonia) and L-alanine (transamination to form pyruvate), which have uncharged side chains. L-VG is both a substrate and a mechanism-based inactivator of the enzyme [Feng, L., and Kirsch, J. F. (2000) Biochemistry 39, 2436-2444], but the partition ratio, k(cat)/k(inact), is unaffected by the Glu47 mutations. ACC synthase primarily catalyzes the beta,gamma-elimination of MTA from the (R,S) diastereomer of SAM to produce L-VG [Satoh, S., and Yang, S. F. (1989) Arch.Biochem. Biophys. 271, 107-112], but catalyzes the formation of ACC to a lesser extent via alpha,gamma-elimination of MTA. The partition ratios for (alpha,gamma/beta,gamma)-elimination on (R,S)-SAM are 0.4, < or =0.014, and < or =0.08 for the wild-type, E47Q, and E47D enzymes, respectively. The results of these experiments strongly support a role for Glu47 as an anchor for the sulfonium pole of (S,S)-SAM, and consequently a role as an active site determinant of reaction specificity.

Catalytic Domain↗
PubMed2005

Photooxidation of self-assembled monolayers by exposure to light of wavelength 254 nm: a static SIMS study.

Self-assembled monolayers (SAMs) of alkanethiols have been photooxidized by exposure to light from a lamp emitting light with a wavelength of 254 nm. The data confirm that SAM oxidation on exposure to UV light sources occurs in the absence of ozone, but also suggest that the mechanism is different from that observed in previous studies using broad-spectrum arc lamps. In particular, for monolayers on both gold and silver, carboxylic acid-terminated SAMs oxidize significantly faster than methyl-terminated SAMs, in contrast to earlier observations for monolayers exposed to light from a mercury arc lamp. The difference in rates of photooxidation for the two classes of monolayer is significantly greater on silver than on gold. These data support our recent suggestion that while methyl-terminated SAMs are able to pack much more closely on silver than on gold, carboxylic acid-terminated thiols are not able to adopt the same close-packed structures, and their rates of photooxidation on silver are similar to, or slightly greater than, those measured for the same adsorbates on gold. Surface potential measurements were made for carboxylic acid- and methyl-terminated SAMs using a Kelvin probe apparatus. It was found that the work functions of carboxylic acid-terminated SAMs are significantly greater than those of methyl-terminated monolayers. It is concluded that these data are consistent with the oxidation reaction being initiated by "hot" electrons generated following the interaction of photons with the metallic substrate.

Gold↗
PubMed2006

Structure and identity of 4,4'-thiobisbenzenethiol self-assembled monolayers.

Self-assembled monolayers (SAMs) of 4,4'-thiobisbenzenethiol (TBBT) can be formed on Au surface spontaneously. The structural characteristics and adsorption behavior of TBBT SAMs on Au have been investigated by surface enhanced Raman scattering (SERS), electrochemical cyclic voltammetry (CV), ac impedance spectroscopy (EIS), and atomic force microscopy (AFM). It is demonstrated that TBBT adsorbed on Au by losing a H atom, forming one Au-S bond, and the other mercapto group is free at the surface of the monolayer owing to the presence of the nu(S-H) at 2513 cm(-1) and the delta(C-S-H) at 910 cm(-1) in SERS. The enhancement of the vibration of C-S (1064 cm(-1)), the aromatic C-H vibration (3044 cm(-1)), and the absence of the vibration of S-S illustrate TBBT adsorbed on Au forming a monolayer with one benzene ring tilted with respect to the Au surface. The interpretation of the observed frequencies is aided by ab initio molecular orbital (MO) calculations at the HF/6-31G level of theory. Electrochemical CV and EIS indicate TBBT monolayers can passivate the Au effectively for its low ratio of pinhole defects (theta = 99.6%). AFM studies give details about the surface morphology. The applications of TBBT SAMs have been extensively investigated by exposure of Cu2+ ion to TBBT SAMs on Au and covalent adsorption of metal nanoparticles. Electrochemical, X-ray photoelectron spectroscopic, and SERS results indicate that Cu2+ can react with TBBT SAMs and present on TBBT SAMs as Cu(I). A scanning electron microscopic image of Ag nanoparticles on TBBT/Au and the Raman spectrum of TBBT in smooth macroscopic Au/TBBT SAMs/Ag nanoparticle sandwich structure indicate that metal nanoparticles can be adsorbed on TBBT SAMs effectively through covalent linkage.

Journal Article↗
PubMed2004

Dielectric properties and frequency response of self-assembled monolayers of alkanethiols.

This paper presents dielectric properties of alkanethiol self-assembled monolayers (SAMs) under an ac electric field. Using a Hg-SAM/SAM-Hg junction, we measured the ac impedance of alkanethiol SAMs using a sinusoidal perturbation of 30 mV (peak-to-peak) with frequency ranging from 1 Hz to 1 MHz at zero bias. Semicircles at higher frequencies and at middle frequencies along with Warburg lines at lower frequencies were observed in complex plane impedance plots, that is, Nyquist plots. The frequency response of SAMs was analyzed by modeling the junction using an equivalent circuit and fitting the Nyquist plots. The semicircles at higher frequencies are attributed to the effect of the SAM/SAM interfaces, and the ones at middle frequencies are attributed to the effect of alkanethiol SAMs. The comparison in the plots of the imaginary part of the impedance Z against frequency for the bare Hg electrodes (in pure ethanal) and the SAM-covered Hg electrodes (in alkanethiol solution) supports the analysis. The Warburg lines are attributed to a certain ionic impurity. The dielectric loss spectra are further analyzed. Chain-length-dependent peaks, which correspond to different relaxation mechanisms, at higher frequencies and middle frequencies were observed in the spectra of the dissipation factor (tan delta vs frequency). The peaks move to small frequency with the increase of chain length of alkanethiols. Using a correlation of peak position with the chain length, we then derived active energies of 39-99 meV for alkanethiol SAMs of C7-C18 under an ac electric field.

Journal Article↗
PubMed2004

Role of surface heterogeneity and molecular interactions in the charge-transfer process through self-assembled thiolate monolayers on Au(111).

A comparative study of charge-transfer processes from/to methyl-terminated and carboxylate-terminated thiolate-covered Au(111) surfaces to/from immobilized methylene blue (MB) molecules is presented. Scanning tunneling microscopy images with molecular resolution reveal the presence of molecular-sized defects, missing rows, and crystalline domains with different tilts that turn the thickness of the alkanethiolate SAM (the spacer) uncertain. The degree of surface heterogeneity at the SAMs increases as the number of C units (n) in the hydrocarbon chain decreases from n = 6. Defective regions act as preferred paths for MB incorporation into the methyl-terminated SAMs, driven by hydrophobic forces. The presence of negative-charged terminal groups at the SAMs reduces the number of molecules that can be incorporated, immobilizing them at the outer plane of the monolayer. Only MB molecules incorporated into the SAMs close to the Au(111) surface (at a distance < 0.5 nm) are electrochemically active. MB molecules trapped in different defects explain the broad shape and humps observed in the voltammogram of the redox couple. The heterogeneous charge-transfer rate constants for MB immobilized into methyl-terminated thiolate SAMs are higher than those estimated for carboxylate- terminated SAMs, suggesting a different orientation of the immobilized molecule in the thiolate environment.

Journal Article↗
PubMed2005

Improved method for the preparation of carboxylic acid and amine terminated self-assembled monolayers of alkanethiolates.

We present an improved method to prepare carboxylic acid (COOH) and amine (NH2) terminated self-assembled monolayers (SAMs) of alkanethiolates. In this method, a small amount of CF3COOH (for COOH-SAM) or N(CH2CH3)3 (for NH2-SAM) is added into the ethanolic solution of alkanethiols during SAM formation. The freshly formed COOH- and NH2-SAMs are then rinsed with an ethanolic solution of NH4OH or CH3COOH, respectively. Both SAMs prepared with the improved method show better quality in terms of surface chemical composition, roughness, and wettability as measured by X-ray photoelectron spectroscopy, atomic force microscopy, and contact angle, respectively. The formation of better SAMs can be attributed to the disruption of interplane hydrogen bonds.

Alkanes↗
PubMed2005

Molecular dynamics simulations of peptide-surface interactions.

Proteins, which are bioactive molecules, adsorb on implants placed in the body through complex and poorly understood mechanisms and directly influence biocompatibility. Molecular dynamics modeling using empirical force fields provides one of the most direct methods of theoretically analyzing the behavior of complex molecular systems and is well-suited for the simulation of protein adsorption behavior. To accurately simulate protein adsorption behavior, a force field must correctly represent the thermodynamic driving forces that govern peptide residue-surface interactions. However, since existing force fields were developed without specific consideration of protein-surface interactions, they may not accurately represent this type of molecular behavior. To address this concern, we developed a host-guest peptide adsorption model in the form of a G(4)-X-G(4) peptide (G is glycine, X is a variable residue) to enable determination of the contributions to adsorption free energy of different X residues when adsorbed to functionalized Au-alkanethiol self-assembled monolayers (SAMs). We have previously reported experimental results using surface plasmon resonance (SPR) spectroscopy to measure the free energy of peptide adsorption for this peptide model with X = G and K (lysine) on OH and COOH functionalized SAMs. The objectives of the present research were the development and assessment of methods to calculate adsorption free energy using molecular dynamics simulations with the GROMACS force field for these same peptide adsorption systems, with an oligoethylene oxide (OEG) functionalized SAM surface also being considered. By comparing simulation results to the experimental results, the accuracy of the selected force field to represent the behavior of these molecular systems can be evaluated. From our simulations, the G(4)-G-G(4) and G(4)-K-G(4) peptides showed minimal to no adsorption to the OH SAM surfaces and the G(4)-K-G(4) showed strong adsorption to the COOH SAM surface, which is in agreement with our SPR experiments. Contrary to our experimental results, however, the simulations predicted a relatively strong adsorption of G(4)-G-G(4) peptide to the COOH SAM surface. In addition, both peptides were unexpectedly predicted to adsorb to the OEG surface. These findings demonstrate the need for GROMACS force field parameters to be rebalanced for the simulation of peptide adsorption behavior on SAM surfaces. The developed methods provide a direct means of assessing, modifying, and validating force field performance for the simulation of peptide and protein adsorption to surfaces, without which little confidence can be placed in the simulation results that are generated with these types of systems.

Adsorption↗
PubMed2005

Controlled crystallization of CaCO(3) on hyperbranched polyglycerol adsorbed to self-assembled monolayers.

The formation of biominerals by living organisms is governed by the cooperation of soluble and insoluble macromolecules with peculiar interfacial properties. To date, most of the studies on mineralization processes involve model systems that only account for the existence of one organic matrix and thus disregard the interaction between the soluble and insoluble organic components that is crucial for a better understanding of the processes taking place at the inorganic-organic interface. We have set up a model system composed of a matrix surface, namely, a self-assembled monolayer (SAM), and a soluble component, hyperbranched polyglycerol. The model mineral calcium carbonate displays diverse polymorphism. It could be demonstrated that the phase selection of calcium carbonate is controlled by the cooperative interaction of the SAM and hyperbranched polyglycerol of different molecular weights (M(n) = 500-6000 g/mol) adsorbed to the SAM. Our studies showed that hyperbranched polyglycerol is adsorbed to polar as well as to nonpolar SAMs. This effect can be related to its highly flexible structure and its amphiphilic character. The adsorption of hyperbranched polyglycerol to the SAMs with different surface polarities resulted in the formation of aragonite for alkyl-terminated SAMs and no phase selection for carboxylate-terminated SAMs.

Adsorption↗
PubMed2005

Thermal study of accumulation of conformational disorders in the self-assembled monolayers of C8 and C18 alkanethiols on the Au111 surface.

The thermal stability of short alkanethiol CH(3)(CH(2))(7)SH (C(8)) and long C(18) self-assembled monolayers (SAMs) is investigated using grazing angle reflection-absorption infrared spectroscopy, cyclic voltammetry, and molecular dynamics simulation. We track the disordering of SAM by untilting and gauche defect accumulation with increasing temperature in the 300-440 K range, a range of interest to tribology. Molecular dynamics simulation with both fully covered and partially covered C(6), C(8), and C(18) monolayers brings out the morphological changes in the SAM, which may be associated with the observed thermal stability characteristics. The molecular dynamics simulations reveal that short-chain C(6) and C(8) alkanethiols are more defective at lower temperature than the long-chain C(18) alkanethiol. With increasing temperature disorder in the SAM, as reflected in both untilting and gauche defect accumulation, tends to saturate at temperatures below 360 K for short-chain SAMs such that any further increase in temperature, until desorption, does not lead to any significant change in conformational order. In contrast the disorder in the long-chain C(18) SAM increases monotonically with temperature beyond 360 K. Thus, in a practical range of temperature, the ability of a SAM to retain order with increasing thermal perturbations is governed by the state of disorder prior to heat treatment. This deduction derived from molecular dynamics simulation helps to rationalize the significant difference we have observed experimentally between the thermal response of short- and long-chain thiol molecules.

Journal Article↗
PubMed2004

Acid-base properties and zeta potentials of self-assembled monolayers obtained via in situ transformations.

Siloxane-anchored, self-assembled monolayers (SAMs) on single crystal Si were prepared with a variety of surface functional groups using a single commercially available surfactant (1-bromo-11-(trichlorosilyl)undecane) followed by in situ transformations. Polar (thioacetate and thiol), nonpolar (methyl), acidic (sulfonic and carboxylic), basic (various amines), and ionic (alkylammonium) surface functionalities were prepared. For primary amine and sulfonate surfaces, the degree of surface charge as a function of pH was determined ex situ using X-ray photoelectron spectroscopy (XPS). Sulfonate SAMs exhibited much higher effective pKa (approximately 2) than dilute sulfonic acid (-5 to -6), and amine SAMs exhibited much lower pKa (approximately 3) than dilute organic amines (approximately 10). This is attributed to the stabilization of nonionized groups by adjacent ionized groups in the SAM. Zeta potentials of these SAMs as a function of pH were consistent with the XPS results and indicated that ionizable SAM surfaces can generate surface potentials much higher than those of nonionic SAMs (thioacetate, methyl) and typical oxide surfaces.

Journal Article↗
PubMed2004

X-ray studies of self-assembled organic monolayers grown on hydrogen-terminated Si(111).

The structure of self-assembled monolayers (SAMs) of undecylenic acid methyl ester (SAM-1) and undec-10-enoic acid 2-bromo-ethyl ester (SAM-2) grown on hydrogen-passivated Si(111) were studied by X-ray reflectivity (XRR), X-ray standing waves (XSW), X-ray fluorescence (XRF), atomic force microscopy, and X-ray photoelectron spectroscopy (XPS). The two different SAMs were grown by immersion of H-Si(111) substrates into the two different concentrated esters. UV irradiation during immersion was used to create Si dangling bond sites that act as initiators of the surface free-radical addition process that leads to film growth. The XRR structural analysis reveals that the molecules of SAM-1 and SAM-2 respectively have area densities corresponding to 50% and 57% of the density of Si(111) surface dangling bonds and produce films with less than 4 angstroms root-mean-square roughness that have layer thicknesses of 12.2 and 13.2 angstroms. Considering the molecular lengths, these thicknesses correspond to a 38 degrees and 23 degrees tilt angle for the respective molecules. For SAM-2/Si(111) samples, XRF analysis reveals a 0.58 monolayer (ML) Br total coverage. Single-crystal Bragg diffraction XSW analysis reveals (unexpectedly) that 0.48 ML of these Br atoms are at a Si(111) lattice position height that is identical to the T1 site that was previously found by XSW analysis for Br adsorbed onto Si(111) from a methanol solution and from ultrahigh vacuum. From the combined XPS, XRR, XRF, and XSW evidence, it is concluded that Br abstraction by reactive surface dangling bonds competes with olefin addition to the surface.

Hydrogen↗
PubMed2005

Self-assembly, characterization, and chemical stability of isocyanide-bound molecular wire monolayers on gold and palladium surfaces.

Self-assembled monolayers (SAMs) of the isocyano derivative of 4,4'-di(phenylene-ethynylene)benzene (1), a member of the "OPE" family of "molecular wires" of current interest in molecular electronics, have been prepared on smooth, {111} textured films of Au and Pd. For assembly in oxygen-free environments with freshly deposited metal surfaces, infrared reflection spectroscopy (IRS) indicates the molecules assume a tilted structure with average tilt angles of 18-24 degrees from the surface normal. The combination of IRS, X-ray photoelectron spectroscopy, and density functional theory calculations all support a single sigma-type bond of the -NC group to the Au surface and a sigma/pi-type of bond to the Pd surface. Both SAMs show significant chemical instability when exposed to typical ambient conditions. In the case of the Au SAM, even a few hours storage in air results in significant oxidation of the -NC moieties to -NCO (isocyanate) with an accompanying decrease in surface chemical bonding, as evidenced by a significant increase in instability toward dissolution in solvent. In the case of the Pd SAM, similar air exposure does not result in incorporation of oxygen or loss of solvent resistance but rather results in a chemically altered interface which is attributed to polymerization of the -NC moieties to quasi-2D poly(imine) structures. Conductance probe atomic force microscope measurements show the conductance of the degraded Pd SAMs can diminish by approximately 2 orders of magnitude, an indication that the SAM-Pd electrical contact has severely degraded. These results underscore the importance of careful control of the assembly procedures for aromatic isocyanide SAMs, particularly for applications in molecular electronics where the molecule-electrode junction is critical to the operational characteristics of the device.

Journal Article↗
PubMed2006

Electron transport through a self-assembled monolayer of thiol-end-functionalized tetraphenylporphines and metal tetraphenylporphines.

The monolayers of several thiol-end-functionalized tetraphenylphophines (SH-TPP) and metal tetraphenylporphines (SH-MTPP) were self-assembled on gold surfaces and identified by cyclic voltammetry (CV), electrochemical impedance spectroscopy, scanning electrochemical microscopy, and the contact angle. The CV peaks of the [Fe(CN)6]3-/ [Fe(CN)6]4- couple were used to identify the efficiency of electrons transferring through the self-assembled monolayer (SAM). The results suggested that SH-TPP and SH-MTPP could form high-quality SAMs on gold surfaces. The SAMs blocked electron transport from the gold electrode to solution. When the length of the thiol-end-link spacer (alkyl group) increased, the electron transport ability of the SAM decreased because of the increased insulator properties of the alkyl chain. With the insertion of metallic ions, the electron transport ability of the SAM of SH-MTPP increased compared to that of the SAM of SH-TPP, which was probably due to the fact that (i) the insertion of metallic ions changed the molecular structure and the molecular structure of SH-MTPP played an important role in electron transport through the SAM and (ii) the insertion of metallic ions increased the electron tunneling probability through the monolayer.

Journal Article↗
PubMed2006

Strong resistance of oligo(phosphorylcholine) self-assembled monolayers to protein adsorption.

In this work, we demonstrate the strong resistance of oligo(phosphorylcholine) (OPC) self-assembled monolayers (SAMs) to protein adsorption and cell adhesion. OPC SAMs were characterized using X-ray photoelectron spectroscopy (XPS), and protein adsorption was measured using a surface plasmon resonance (SPR) sensor. Results are compared with those of phosphorylcholine (PC) SAMs. Despite the existence of negative charge on OPC SAMs and the simple synthesis procedure of OPC thiols, OPC SAMs resist protein adsorption as effectively as or better than PC SAMs formed from highly purified PC thiols. The ease of their preparation and the effectiveness of their function make OPC SAMs an attractive alternative for creating nonfouling surfaces.

Adsorption↗