Factors resisting protein adsorption on hydrophilic/hydrophobic self-assembled monolayers terminated with hydrophilic hydroxyl groups

The hydroxyl-terminated self-assembled monolayer(OH-SAM),as a surface resistant to protein adsorption,exhibits substantial potential in applications such as ship navigation and medical implants,and the appropriate strategies for designing anti-fouling surfaces are crucial.Here,we employ molecular dynamics simulations and alchemical free energy calculations to systematically analyze the factors influencing resistance to protein adsorption on the SAMs terminated with single or double OH groups at three packing densities(∑=2.0 nm^(-2),4.5 nm^(-2),and 6.5 nm^(-2)),respectively.For the first time,we observed that the compactness and order of interfacial water enhance its physical barrier effect,subsequently enhancing the resistance of SAM to protein adsorption.Notably,the spatial hindrance effect of SAM leads to the embedding of protein into SAM,resulting in a lack of resistance of SAM towards protein.Furthermore,the number of hydroxyl groups per unit area of double OH-terminated SAM at ∑=6.5 nm^(-2) is approximately 2 to 3 times that of single OH-terminated SAM at ∑=6.5 nm^(-2) and 4.5 nm^(-2),consequently yielding a weaker resistance of double OH-terminated SAM towards protein.Meanwhile,due to the structure of SAM itself,i.e.,the formation of a nearly perfect ice-like hydrogen bond structure,the SAM exhibits the weakest resistance towards protein.This study will complement and improve the mechanism of OH-SAM resistance to protein adsorption,especially the traditional barrier effect of interfacial water.

The lipase monolayer film self-assembly on the negatively charged poly(ethylene terephthalate) substrate

The PET-CO2- film was prepared and the lipase was assembled on the surface of the PET-CO2- substrate The structure at the surface and activity of lipase/PET monolayer were studied by ATR-FTIR and AFM, and other methods.

Self-assembly to monolayer graphene film with high electrical conductivity

Monolayer chemically converted graphene （CCG） nanosheets can be homogeneously self-assembled onto silicon wafer modified by 3-aminopr- opyl triethoxysilane （APTES） to form very thin graphene film. The CCG film was characterized by FT-IR, XRD, SEM, TEM and AFM. Results show that CCG sheets formed monolayer film after assembled onto silicon wafer and there is a very tight chemical bond between sheets and wafer. Furthermore, the electrical measurements revealed that the monolayer graphene film has an excellent electrical conductivity.

The Effects of Contact Interface on the Friction Characteristics of Self-assembly Monolayers

The effects of different contact interfaces on the friction characteristics of OTS self-assembled monolayers were investigated by a universal micro-tribometer in different sliding velocities. The results indicate that there exist lower friction coefficients between OTS SAMs and Ti, Ni and Cu films deposited on GCr15 steel balls than those between OTS SAMs and GCr15 steel ball. The friction coefficient between OTS SAMs and Ti film is the largest, and the friction coefficient between OTS SAMs and Cu film is the least in these three films, which depends on the intrinsic characteristics of the materials. The friction coefficients between OTS SAMs and GCr15 steel ball and three nanometer films increase with the sliding velocity increasing, which can be explained by the relaxation characteristics of OTS molecules.

Colloidal monolayer self-assembly and its simulation via cellular automaton model

A wafer-scale colloidal monolayer consisting of SiO2 spheres is fabricated by a method combining spin coating and thermal treatment for the first time. Moreover, a new cellular automaton model describing the self-assembly process of the colloidal monolayer is introduced. Rather than simulate molecular self-assembly to establish the most energetically favored position, we reconstruct the self-assembly of the colloidal monolayer by adjusting several simple transition rules of a cellular automaton. This model captures the main self-assembly characteristics of SiO2 spheres, including experimental processing time, morphology, and some statistics. It possesses the advantage of less calculation and higher efficiency, paving a new way to simulate a mesoscopic system.

Self-Assembled Monolayers (SAMs): Which Perspectives in Implant Dentistry?

Self-assembled monolayers (SAMs) are ordered organic films formed by adsorption of an active organic coating on a solid surface. Their formation provides an alternative, highly innovative, to current traditional chemical treatments of the titanium surfaces. For this reason the structural phases, the formation and the growth of SAMs is described from a surface science point of view. Particulars are given to SAMs on titanium concerning surface morphology, chemical composition and affinity of specific head group for Ti surfaces (silanes, siloxane, phosphonates and phosphates). Preparation, coating methodologies, limitations and techniques used for the characterization of SAMs are reported. For their physicochemical characteristics and micro-nano scale features some perspectives of using SAMs in biomedical application are outlined.

Dielectric Properties of Self-assembled Monolayers of Dithiols

Dielectric properties of dithiol self-assemble monolayers （SAMs） under ac electric field were presented, Using a Hg-SAM/SAM-Ⅱg junction, the ac impedances of dithiol SAMs were measured using a sinusoidal perturbation of 30 mV （peak to-peak） with the frequency ranging from 1 Hz to 1 MHz at zero bias. The contributions from dithiol SAMs and solvent interlayers were separated due to their different behaviors at ac impedance. The peak position in the loss spectra （the plot; of tgδ vs. frequency） moves to low frequcney with the incrcase of chain length of dithiols. Using a correlation of peak position with the chain length, the active energies of 23-39 meV for dithiol SAMs of C6-C10 under an ac electric field were derived,

Tunneling Electron Induced Fluorescence from Single Porphyrin Molecules Decoupled by Striped-Phase Octanethiol Self-assembled Monolayer

We investigate tunneling electron induced luminescence from isolated single porphyrin molecules that are decoupled by striped-phase self-assembled monolayer of octanethiol from the underneath Au（111） substrate. Intrinsic single-molecule electroluminescence has been realized by such decoupling at both bias polarities. The photon emission intensity acquired from the molecular lobe is found stronger than that from the molecular center. These re- sults provide useful information on the understanding of electroluminescent behavior and mechanism in molecular tunnel junctions.

Attachment of tyrosinase on mixed self-assembled monolayers for the construction of electrochemical biosensor

A mixed self-assembled monolayers （SAMs） of thioctic acid （T-COOH） and thioctic acid amide （T-NH2） were used to immobilize tyrosinase for fabricating biosensor. The results showed that the mixed SAMs prepared from solution at the ratio of 1：4 provided an excellent microenvironment for enzymatic reaction between tyrosinase and substrate. The biosensor exhibited a fast response and high sensitivity for sensing substrate.

Enhanced Hole-Injection Property in an OLED with a Self-assembled Monolayer of Hole-Transporting TPD on Thin Au as the Anode

A thioester-functionalized triphenylamine hole-transporting molecule （TPD-SAc） was synthesized and self-assembled to form a monolayer on an ultra-thin Au film supported on indium-tin oxide glass. The modified surface was characterized by aqueous contact angle, ellipsometer, atomic force microscopy, X-ray photoelectron spectroscopy, and ultraviolet pho- toelectron spectrometer to substantiate the formation of compact and pinhole-free monolayers. The modified organic light emitting diode device [indium-tin oxide/Au （5 nm）/self-assembled monolayers （SAM）/TPD （50 nm）/Alq3 （40 nm）/TPBI （15 nm）/LiF （1 nm）/A1 （100 nm）] showed a luminance of 7303.90 cd/m^2 and a current efficiency of 8.49 cd/A with 1.78 and 2.29-fold increase, respectively, compared to the control device without SAM. The improvements were attributed to the enhanced compatibility of the organic-inorganic interface, matched energy level by introduction of an energy mediating step and superior hole-injection property of SAM molecules.

Electrochemical Behavior and Determination of Trifluoperazine at Decanethiol Self-Assembled Monolayer Modified Gold Electrodes

The electrochemical behavior of trifluoperazine at decanethiol self-assembledmonolayer (SAM) modified gold electrodes (i. e. C_(10) H_(21) SH/Au) has been studied,Trifluoperazine can effectively accumulate on C_(10) H_(21) SH/Au electrodes and generate asensitive anodic peak at about 0.63 V (vs. SCE) in 0.05 mol/L pH 9.4 Na_2 B_4 O_7 buffer solution.Under the selected conditions, the anodic peak current was linear to trifluoperazine concentrationin the range of 5.0 X 10^(-7)-3.O X 10^(-3) mol/Lwith correlation coefficient of 0.997, thedetection limit was 3.0 X 10^(-5) mol/L. This method was applied to the determination oftrifluoperazine in drug samples and the recovery was 97.3%-104.0% It was found that sodium dodecylsulfate (SDS) could make the anodic peak current increase. In the presence of SDS, the peak at about0.63 V turned into two peaks, resulting from the change of the electrochemical mechanism.

The Molecular Recognition Characteristics of ω-MercaptoMethoxy Poly(Ethylene Glycol) Self-assembled Monolayer at Gold Electrode and the Detection of Dopamine in Serum

Self assembled monolayers (SAMs) of to-mercapto methoxy poly(ethylene glycol)(MPEG) on gold electrode were used as a means to detect dopamine. Dopamine (DA) had good response at the MPEG film electrode and ascorbic acid (AA) was repelled from the SAMs. TheMPEG film is a biocompatible film, there was no adsorption of biosample and no inactivation atelectrode surface when it was used to detect DA in biosamples.

Characterization of Self-assembled Monolayers on Gold Electrode Using Electrochemical Quartz Crystal Microbalance

The electrochemical quartz crystal microbalance (EQCM) is used to investigate the characteristics of the thiolated self-assembled monolayer(SAM) on gold surface.A 5MHz QCM element serves as both the mass-sensitive sensor and the working electrode of the electrochemical system.The 6-mecapto-1-hexanol and and the 16-mer oligonucleotide with a mercaptohexyl group at the 5'-phosphate end are utilized to form the SAM on the gold electrode.The frequency response of the QCM during cyclic voltammetry (CV) scanning and cbronoamperometry are recorded together with the electrochemical current.The experimental results indicates that the frequency response is more sensitive to the surface coverage.Therefore,the response of the EQCM reveals more details of the SAM on gold electrode.It is especially useful for analysing the immobilization quality,such as probe orientation and coverage,of the SAM.

Preparation and Characterization of SrTiO_3 Thin Film on Functional Organic Self-Assembled Monolayers

SrTiO3 thin film was successfully prepared on the functionalized organic self-assembled monolayers（SAMs） by the Liquid Phase Deposition（LPD） method.The as-prepared samples were characterized by X-ray diffraction（XRD）,atomic force microscope（AFM）,scanning electron microscopy（SEM） and metallographic microscope.Measurement of contact angle showed that the hydrophobe substrate was changed into hydrophile by UV irradiation.AFM photographs of octadecyl-trichloro-silane self-assembled monolayer（OTS-SAM） surface approved that UV irradiation did change the morphology of OTS monolayer and provided evidence for the conversion of hydrophilic characteristic.Photographs of Metallographic Microscope showed that OTS-SAM had an active effect on the deposition of SrTiO3 thin film.XRD and SEM indicated that the thin film was of pure cubic phase SrTiO3 and composed of nanosized grains with a size in the range of 100-500 nm.The formation mechanism of the SrTiO3 film was proposed.

Self-Assembled Monolayer of Lipoic Acid on Gold and Its Application to Rapid Determination of 2, 3, 7, 8-Tetrachlorodibenzo-p-Dioxin

Lipoic acid (LA) has received great attention in the area of gold surface functionalization. In this study, LA was employed as a linker for the attachment of antibody to the gold surface of surface plasmon resonance (SPR) chip. By using this chip in a homemade SPR immunosensor, low molecular weight compound 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) can be detected at a low level of 0.01 ng/mL. There is a good linear relationship(R2 =0.943 1) between the results of SPR biosensor and enzyme-linked immunosorbent assay(ELISA).

Simultaneous Determination of Dopamine and Uric Acid at 2-Amino-5-mercapto-[1, 3, 4]triazole Self-assembled Monolayers Gold Electrode

A newly synthesized reagent 2-amino-5-mercapto-[1, 3, 4]triazole (MATZ) has been usedto fabricate self-assembled monolayers (SAMs) on gold electrode for the first time. The SAMselectrode was characterized by electrochemical methods and scanning electronic microscopy (SEM),the SAMs electrode can be used to determinate dopamine (DA) and uric acid (UA) simultaneouslywith a detection limit of 8×10-7 mol/L for DA and 1×10-6 mol/L for UA respectively. The SAMscan also be used to detect the contents of DA and UA in synthetic urine sample with satisfactoryresults.

Immobilization of antibodies on the self-assembled monolayer by antigen-binding site protection and immobilization kinetic control

The orientation of the biological molecule immobi-lized on a solid surface has been critical in devel-opment of various applications. In this study, ori-entation of antibody was retained by protecting the antigen-binding site of the antibody prior to immo-bilization to -functionalized mixed self-assembled monolayer (SAM) of 12-mercaptododecanoic acid and 1-heptanethiol. More importantly, the number of immobilization bonds formed between each an-tigen-binding site protected antibody molecule and the solid surface was controlled by optimizing the mole fraction of the activated carboxyl group of the linker molecules in the mixed SAM. The amount of antibody used in this study was approximately equivalent to the amount for one monolayer surface coverage. The resulting activity of protected immo-bilized antibody was about 10 fold higher than that of random immobilized

Stability Behaviour of Monolayer Tetraether Lipids on the Amino-Silanised Silicon Wafer: Comparative Study between Langmuir-Blodgett Monolayers with Self-Assembled Monolayers

This study investigated the stability behaviour of molecular monolayer symmetric chemically modified tetraether lipids caldarchaeol-PO4 on the amino-silanised silicon wafer using Langmuir-Blodgett films, Self Assembling Monolayers (SAMs), ellipsometry, and atomic force microscopy (AFM). The monolayers of caldarchaeol-PO4 were stable on the solid surface amino-silanised silicon wafer. The organizations of molecular monolayers caldarchaeol-PO4 by Langmuir-Blodgett method and SAMs have been analyzed. The surface of pressure in Langmuir-Blodgett processing is carried out monolayers caldarchaeol-PO4 more flat island inhomogeneous. Another method of monolayers caldarchaeol-PO4 by SAMs is showed a large flat domain. Monolayers caldarchaeol-PO4 by Langmuir-Blodgett method seems to be stable and chemically resistant after washing with organic solvent and an additional treatment ultrasonification with various thickness lipids arround 2 nm to 6 nm. Conversely, monolayer caldarchaeol-PO4 by SAMs appears fewer than monolayers caldarchaeol-PO4 by Langmuir-Blodgett method, the thickness of various from 1 nm to 3 nm.

Studies of Self-assembled Monolayers Formed by Imidazofine on Iron Surface by SEM and SECM

The self-assembled monolayers （SAMs） of imidazoline （IM） on the iron surface were characterized by scanning electron microscope （SEM） and scanning electrochemical microscopy （SECM）. The results showed that SAMs were an effective inhibition film for iron.

The Electrochemistry of Cytochrome c at a Viologen-thiol Self-Assembled Monolayer

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