Controlled crystallization of hydroxyapatite under hexadecylamine self-assembled monolayer

The role of self assembled monolayer in inducing the crystal growth was investigated by X ray diffractions (XRD), and scanning electron microscopy (SEM). Results show that crystallization in the absence of monolayer results in a mixture of poorly crystallized calcium phosphates, including hydroxyapatite (HAP) and octacalcium phosphate (OCP), while the presence of self assembled monolayer gives rise to oriented and well crystallized HAP crystals. Moreover, the HAP crystal grows very quickly under the self assembled monolayer, whereas very little calcium phosphate crystals grow without the monolayer. It is rationalized that the hexadecylamine monolayer with high polarity and charged density leads to increase supersaturation and lower the interfacial energy, which attributes to the HAP crystals nucleation. On the other hand, the positive headgroups construct the ordered "recognized site" with distinct size and topology, which results in the oriented HAP crystals deposit.

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.

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.

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.

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.

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.

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.

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

Preparation and characterization of 3-mercaptopropyl trimethoxysilane self-assembled monolayers

Silane coupling regent （3-mercaptopropyl trimethoxysilane （MPTS）） was prepared on the single-crystal silicon substrate to form 2-dimensional self-assembled monolayers （SAMs）. The growth behavior of SAMs formed from 3-MPTS was investigated using atomic force microscopy （AFM）, contact angle measurements, ellipsometry, and X-ray photoelectron spectroscopy （XPS）. The formation behavior of MPTS SAMs was investigated by a series of AFM images and the roughness of MPTS SAMs on silicon substrates with the assembling time from 1 min to 24 h. The water contact angle measurements indicated the growth behavior of MPTS that correlated with the AFM measurements at different immersion times, too. The chemical states of the typical elements in the MPTS SAMs were analyzed using X-ray photoelectron spectroscopy. The results show that MPTS is self-assembled on the substrate.

Nano-tribological characteristics of lanthanum-based thin films on sulfonated self-assembled monolayer of 3-mercaptopropyl trimethoxysilane

Silane coupling reagent （3-mercaptopropyl trimethoxysilane （MPTS）） was prepared on silicon substrate to form two-dimensional Self-Assembled Monolayer （SAM） and the terminal -SH group in the film was in situ oxidized to -SO3H group to endow the film with good chemisorption ability. Thus, lanthanum-based thin films were deposited on oxidized MPTS-SAM to form rare earth composite thin films （RE thin films）, making use of the chemisorption ability of the -SO3H group. Atomic Force Microscope （AFM）, X-ray Photoelectron Spectrometry （XPS）, and contact angle measurements were used to characterize the RE thin films. Adhesive force and friction force of the RE thin films and silicon substrate were measured under various applied normal loads and scanning speed of AFM tip. The results showed that the friction force increased with applied normal loads and scanning speed of AFM tip. To study the effect of capillary force, tests were performed in various relative humidities. The results showed that the adhesive force of silicon substrate increased with relative humidity and the adhesive force of RE thin films only increased slightly with relative humidity. Research showed that surfaces with higher hydrophobic property reveal lowered adhesive and friction forces.

Seed-mediated growth of gold nanoparticles using self-assembled monolayer of polystyrene microspheres as nanotemplate arrays

Arrays of noble metal nanoparticles show potential applications in （bio-）sensing, optical storage, surface-enhanced spectroscopy, and waveguides. For all such potential devices, controlling the size, morphology, and interparticle spacing of the nanoparticles is very important. Here, we combine seed-mediated growth with nanosphere lithography to study the controllable growth of gold nanoparticles （Au NPs）, in which the self-assembly monolayer of polystyrene （PS） on a silicon surface is used to guide the modification of allaunesilanes and the subsequent adsorption of gold seeds; seed-mediated growth is applied to controlling the morphology and size of Au NPs. The size of adsorption region （determining the number of adsorbed gold seeds） is controlled by etching PS microspheres with oxygen plasma or annealing PS microspheres at the glass transition temperature. The size and morphology of the Au NPs are controlled by changing growth conditions. In such a way, we have achieved the dual control of the obtained Au NPs. Preliminary results show that this strategy holds a great promise. This approach can also be extended to a wide range of materials and substrates.

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.

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 Channel Behavior of Gramicidin D in the Self-assembled Monolayer

It was found for the first time that gramicidin D (GD) molecules can be incorporated into the ODM monolayer which is self-assembled on the surface of the gold electrode and form monovalent cation channels.

A New Self-Assembled Monolayer of Fullerene Derivative and ItsPhotoelectric Conversion Property

A new self-assembled monolayer (SAM) of fullerene derivative has been fabricated and their photoelectric conversion property has been observed. The SAM was fabricated on indium-tin-oxide (ITO) and quartz by amide bonding. It was characterized bq contact angle, UV spectrum. and cyclic voltammetry. The mild fabrication conditions and the stability of the SAM provides a way to build three-dimensional structure more easily.

Permselectivity of 4－Aminophenol，Paracetanol and Phenacetin on the Self－Assembled n－Alkanethiol Monolayer Modified Gold Electrode

The gold electrodes coated by n-alkanethiol with various chain lengths were used to study the permeability of uric acid,ascorbic acid,4-aminophenol,paracetanol and phenacetin by means of linear sweep voltammetry.The results show that the optimum chain length is n=10.The improvements in the selectivity and the stability of the amperometric detection of these compounds in a flow stream were obtained by n-alkanethiol self assembled monolayers modified electrodes based on their differences in the hydrophobicity and the permeability.