Allylamine Monomer Research Articles

The osteogenesis performance of titanium modified via plasma-enhanced chemical vapor deposition: in vitro and in vivo studies

Titanium (Ti) and its alloys are widely used in dental implants due to their favorable mechanical properties and biocompatibility. Surface characteristics, including physical and chemical properties, are crucial factors to enhance the osteogenesis performance of Ti. The aim of this study is to evaluate amino group surface modification to facilitate the osteogenic potential and bone repair of dental implants both in vitro and in vivo. Herein, amino group-modified Ti surfaces were constructed via the plasma-enhanced chemical vapor deposition (PECVD) technique with an allylamine monomer. The adhesion, proliferation, alkaline phosphate activity and osteogenesis-related genetic expression of MG-63 cells on the surfaces were performed in vitro and presented a significant increase in amino group-modified Ti compared with that in Ti. The in vivo study in miniature pigs was evaluated through micro-computed tomography analysis and histological evaluation, which exhibited enhanced new bone formation in amino group-modified Ti compared with that in Ti after implantation for 4, 8 and 12 weeks. Consequently, amino group surface modification with the PECVD technique may provide a promising modification method to enhance the osteogenesis performance of Ti implants.

Controlled biodegradation of metallic biomaterials by plasma polymer coatings using hexamethyldisiloxane and allylamine monomers

Abstract Plasma enhanced chemical vapor deposition is a promising process for the generation of tailor-made polymer coatings on medical devices in order to improve their implant/ host interaction. The ultra-thin coatings can fulfil a variety of purposes, depending on the monomers used, the process conditions and the location of the coated implants in the human body. In addition, even complex geometries can be coated easily and without the application of solvents. Particularly hydrophilic and hydrophobic plasma polymer coatings can improve biocompatibility, especially in blood contact. Furthermore, the selection of the monomers used enables the generation of specific functional groups for further surface immobilization of drugs, such as proteins, by chemical crosslinking. The release of toxic residues from polymeric implants, such as monomers, additives or degraded components, can also be avoided. The aim of our investigation was the generation of plasma polymer films, their characterization and application as coatings for biodegradable metallic biomaterials in order to retard the degradation process. Metallic biomaterials, in various forms are frequently used in orthopaedics, dentistry, cardiovascular and neurosurgical equipment, because of their tensile strength, fracture toughness, fatigue strength and electrical conductivity. Plasma polymerization was performed using the monomers hexamethyldisiloxane and allylamine. The resulting plasma polymers were analysed in an accelerated degradation test. Both plasma polymers appear to be promising, while polyHMDSO appears to degrade over time and polyallylamine indicates to be stable.

Chemically interconnected light-weight 3D-carbon nanotube solid network

Owing to the weak physical interactions such as van der Waals and π-π interactions, which hold nanotubes together in carbon nanotube (CNT) bulk structures, the tubes can easily slide on each other. Creating covalent interconnection between individual carbon nanotube (CNT) structures could remarkably improve the properties of their three-dimensional (3D) bulk structures. The creation of such nanoengineered 3D solid structures with improved properties and low-density remains one of the fundamental challenges in real-world applications. Here, we report the scalable synthesis of low-density 3D macroscopic structure made of covalently interconnected nanotubes using free-radical polymerization method after functionalized CNTs with allylamine monomers. The resulted interconnected highly porous solid structure exhibits higher mechanical properties, larger surface area and greater porosity than non-crosslinked nanotube structures. To gain further insights into the deformation mechanisms of nanotubes, fully atomistic reactive molecular dynamics simulations are used. Here we demonstrate one such utility in CO2 uptake, whose interconnected solid structure performed better than non-interconnected structures.

Effect of synthesis variables of plasma synthesized polymers on growth of HepG2 cells

Low pressure plasma polymer films were synthesized using pyrrole and allylamine monomers and adding iodine was used (or not) for the reaction in both cases. They were polymerized on glass substrates under the same reaction conditions. Polymerization of allylamine was also studied at different operating powers. These thin polymer films were used as culture surfaces for HepG2 cells, a cell line derived from a human hepatoma. The proliferation, differentiation and two-dimensional propagation until obtaining monolayer of the cells was studied on the different synthetized films and correlations were established between the conditions of synthesis, the physicochemical characteristics obtained and the performance as substrates for the cellular growth.

Partial hydrophilic modification of biaxially oriented polypropylene film by an atmospheric pressure plasma jet with the allylamine monomer

In this paper, the partial modification of the biaxially oriented polypropylene (BOPP) film for potential biological and packaging applications was achieved via hydrophilic modification using atmospheric pressure plasma jet (APPJ). In the APPJ system, the allylamine (ALA) monomer was polymerized on the BOPP surface by either the Ar/O2 or the He/O2 plasma. The results showed that plasmatic modification created many micro/nano sized holes on the BOPP film, which increased the surface roughness dramatically and the increased roughness enhanced the combining intensity between the BOPP film and the ALA polymer. However, such a plasmatic modification increased the water vapor permeability. The FTIR and XPS characterizations showed that the amine groups were grafted onto the BOPP film, and the contact angle of the BOPP film decreases from 98.5° to 8°. Compared with the BOPP films treated by the Ar or He plasma, the barrier property of the modified BOPP film increased significantly when the ALA polymer was incorporated. The bio-affinity/toxicity of ALA polymer was illustrated by the attachment of the cultured SMMC-7721 hepatoma cells on the modified BOPP film. The significant enhancement in the cell density indicated that modified BOPP film was highly bio-compatible and non-toxic, especially treated with the Ar/O2/ALA plasma.

Graphene oxide functionalized polyethersulfone membrane to reduce organic fouling

Graphene-oxide can be used to modify a polymeric membrane surface to render the surface less susceptible to organic fouling. In this study, a three-step method is developed to covalently bind graphene oxide (GO) nanosheets onto a polyethersulfone (PES) support to create an ultrafiltration membrane that is resistant to organic fouling. First, amine functional groups are grafted onto a PES surface by UV-induced graft co-polymerization of allylamine monomer. Next, trimesoyl chloride (TMC, 0.2wt% in hexane) and GO nanosheets (2, 4 and 6wt% in anhydrous acetonitrile) are attached onto the polyallylamine modified membrane surface by spin coating, allowing covalent binding to take place between TMC and the amine functional group, and also between TMC and the hydroxyl or carboxylic functional groups of GO. Covalent bonding was confirmed by the emerging ester or anhydride peaks by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The GO membrane morphology was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The molecular weight cut offs (MWCO) of the GO (2, 4 and 6wt%) modified membranes were determined to be 380, 140, and 75kDa respectively. The membrane with 4wt% GO (PES-GO-4) was chosen for further study because it exhibited higher pure water flux and rejection than the other GO formulations. The PES-GO-4 membrane exhibited 2.6 times greater flux recovery than an unmodified PES-UF membrane of comparable MWCO. This method is a simple, effective way to create a robust, high flux UF membrane that is resistant to organic fouling. Such a membrane could be applied in water or wastewater treatment applications, such as pretreatment for reverse osmosis.

Single addition of an allylamine monomer enables access to end-functionalized RAFT polymers for native chemical ligation.

A novel method for the introduction of a single protected amine-functional monomer at the chain end of RAFT polymers has been developed. This monomer addition, in concert with native chemical ligation, facilitated the development of a simple and versatile method for the end-functionalization of polymers with peptides.

Increasing binding density of yeast cells by control of surface charge with allylamine grafting to ion modified polymer surfaces

Plasma immersion ion implantation (PIII) treatment of polymers creates a biointerface capable of direct covalent immobilization of biomolecules. The immobilization of protein molecules is achieved by covalent bonds formed between embedded radicals on the treated surface and amino acid side chains and cells can be immobilized through cell-wall proteins. The attachment density of negatively charged entities on a PIII treated surface is inhibited by its negative surface charge at neutral pH. To reduce the negative charge of PIII treated surfaces in phosphate buffer (pH 7.4, 11mM), we develop an effective approach of grafting allylamine monomers onto the treated surface. The results reveal reactions between allylamine and radicals on the PIII treated surface. One of these triggers polymerization, increasing the number of amine groups grafted. As a consequence, the PIII treated polystyrene surface after allylamine exposure becomes more hydrophobic and less negatively charged in phosphate buffer. Using yeast cells as an example, we have shown a significant improvement (6–15 times) of cell density immobilized on the PIII treated surface after exposure to allylamine.

Immobilization of Heparan Sulfate on Electrospun Meshes to Support Embryonic Stem Cell Culture and Differentiation *

As our understanding of what guides the behavior of multi- and pluripotent stem cells deepens, so too does our ability to utilize certain cues to manipulate their behavior and maximize their therapeutic potential. Engineered, biologically functionalized materials have the capacity to influence stem cell behavior through a powerful combination of biological, mechanical, and topographical cues. Here, we present the development of a novel electrospun scaffold, functionalized with glycosaminoglycans (GAGs) ionically immobilized onto the fiber surface. Bound GAGs retained the ability to interact with GAG-binding molecules and, crucially, presented GAG sulfation motifs fundamental to mediating stem cell behavior. Bound GAG proved to be biologically active, rescuing the neural differentiation capacity of heparan sulfate-deficient mouse embryonic stem cells and functioning in concert with FGF4 to facilitate the formation of extensive neural processes across the scaffold surface. The combination of GAGs with electrospun scaffolds creates a biomaterial with potent applicability for the propagation and effective differentiation of pluripotent stem cells.

Electrostatically Directed Visual Fluorescence Response of DNA-Functionalized Monolithic Hydrogels for Highly Sensitive Hg2+ Detection

Hydrogels are cross-linked hydrophilic polymer networks with low optical background and high loading capacity for immobilization of biomolecules. Importantly, the property of hydrogel can be precisely controlled by changing the monomer composition. This feature, however, has not been investigated in the rational design of hydrogel-based optical sensors. We herein explore electrostatic interactions between an immobilized mercury binding DNA, a DNA staining dye (SYBR Green I), and the hydrogel backbone. A thymine-rich DNA was covalently functionalized within monolithic hydrogels containing a positive, neutral, or negative backbone. These hydrogels can be used as sensors for mercury detection since the DNA can selectively bind Hg(2+) between thymine bases inducing a hairpin structure. SYBR Green I can then bind to the hairpin to emit green fluorescence. For the neutral or negatively charged gels, addition of the dye in the absence of Hg(2+) resulted in intense yellow background fluorescence, which was attributed to SYBR Green I binding to the unfolded DNA. We found that, by introducing 20% positively charged allylamine monomer, the background fluorescence was significantly reduced. This was attributed to the repulsion between positively charged SYBR Green I by the gel matrix as well as the strong binding between the DNA and the gel backbone. The signal-to-background ratio and detection limit was, respectively, improved by 6- and 9-fold using the cationic gel instead of neutral polyacrylamide gel. This study helps understand the electrostatic interaction within hydrogels, showing that hydrogels can not only serve as a high capacity matrix for sensor immobilization but also can actively influence the interaction between involved molecules.

Preparation and Characterization of a Solid Amine Adsorbent for Capturing CO2 by Grafting Allylamine onto PAN Fiber

Solid amine adsorbents using synthetic fibers instead of silica as the matrix are expected to offer more benefits for the adsorption of CO(2) because of high external surface area, low pressure drops, and flexibility of the matrix fibers. A novel kind of solid amine-containing fibrous adsorbent (PAN-AF) was prepared by preirradiation grafting copolymerization of allylamine onto polyacrylonitrile (PAN) fiber, using the redox system of (NH(4))(2)S(2)O(8)/NaHSO(3) as initiator. The effects of the reaction conditions such as reaction time, temperature, monomer concentration, amount of the initiator on grafting degree were studied. The results showed that the optimal conditions for the grafting copolymerization were using 50% allylamine monomer (V/V) and 1.5% (W/V) initiator and reacting at 100 degrees C for 10 h. FTIR was employed to characterize the corresponding changes on the surface chemical structure of PAN and PAN-AF. Thermal gravimetric analysis was used to evaluate the thermal stability of the materials. Equilibrium adsorption capacities for CO(2) and regeneration behaviors of PAN-AF were determined. Adsorption capacity for CO(2) of PAN-AF with 60.0 wt % grafting degree was 6.22 mmol CO(2)/g PAN-AF. PAN-AF could be completely regenerated by heating in boiling water for 30 min. The CO(2) adsorption performance of the regenerated PAN-AF was almost the same as that of the fresh adsorbent after several cycles, which revealed that PAN-AF exhibited good regenerating stability. The high speed and effective regeneration process proves that PAN-AF has great potential in industrial applications for CO(2) capture.

Photoactive rare earth (Eu3+, Tb3+) hybrids with organically modified silica covalently bonded polymeric chain

1,3-Bis(2-formylphenoxy)-2-propanol (BFPP) is grafted to 3-(triethoxysilyl)-propyl isocyanate (TESPIC) to prepare the organic precursor BFPP-Si. Then, the organic precursor BFPP-Si is coordinated with rare earth ion to obtain the luminescent center RE-BFPP-Si. Allylamine monomer (AM) is modified by TESPIC to form the precursor AM-Si which is then polymerized with the benzoyl peroxide as the initiator to form the polymer precursor PAM-Si. The other polymer precursor polyethylene glycol (PEG)-Si is achieved through the grafting reaction between PEG and TESPIC. Subsequently, the hybrid materials RE-BFPP-Si-PAM or RE-BFPP-Si-PEG are assembled in which RE-BFPP-Si and PAM-Si or PEG-Si connected with Si-O bonds through sol-gel process and characterized with scanning electronic microscopy, X-ray diffraction, and TG-DSC curves. Their photophysical properties are especially studied in details, indicating that the introduction of organic polymer chain is favorable for the luminescence lifetime and quantum efficiency.

Structural characterization and mechanical properties of functionalized pulsed-plasma polymerized allylamine film

Due to its surface properties, especially the presence of abundant amine groups, pulsed-plasma polymerized allylamine (PPAa) is used to manufacture biosensor and modify surface of metallic biomaterials. In the present study, PPAa films on 316L medical stainless steel are prepared by pulsed radio frequency (RF) plasma polymerization using allylamine as a precursor under different duty cycles. The effect of the pulsed duty cycles on the composition, structure, surface morphology, wettability and mechanical properties of PPAa films are investigated by Fourier transform infrared (FTIR) spectroscopy, laser Raman spectra, X-ray photoelectron spectroscope (XPS), atom force microscope (AFM), contact angle measurement, nanoscratch test and substrate straining method. All results of FTIR, XPS and Raman indicate that there are more amine groups from allylamine monomer on the 20/80 film fabricated by 20% duty cycle. The wettability of the 20/80 film is higher than that of 20/30 film prepared using 40% duty cycle. AFM micrographs demonstrate no remarkable differences in the morphological characteristics, but grain size of 20/30 film is larger than that of 20/80 film. The critical force of 20/80 film is about 71.86 mN, higher than that of 20/30 film and has a better scratch resistance. It is estimated that the mechanical properties of the plasma polymerization are different.

Microwave plasma surface modification of silicone elastomer with allylamine for improvement of biocompatibility

The microwave plasma surface modification of silicone elastomer with allylamine was studied to improve the biocompatibility of the material. An effort was made to clarify the relationships among plasma conditions and surface chemical composition, physical surface properties and biocompatibility of material, as well as the stability of plasma deposited layers. ATR-IR, XPS, Ellipsometry measurements, and contact angle measurements were used to investigate the changes of surface. The stability of plasma-treated silicone surfaces were also studied. The results demonstrated that the temperature and pressure had a strong influence on the chemical composition and structure of surface-deposited layer. The layer was nearly completely crosslinking when the modification was carried out at 60 degrees C. The polymerization speed decreased linearly with temperature. The XPS analysis results showed that the nitrogen element content in the surface layer was very high, especially under low pressure. The nitrogen/carbon ratio in the layer even greatly surpassed that of the allylamine monomer. The wettability of the silicone surface was greatly improved after plasma modification, and increased with the quantities of amine groups. The plasma-treated surfaces have good storage stability in air up to 3 months. The wettability of the surfaces decreased incipiently and then it dramatically increased with further time. The human skin fibroblasts were used to evaluate biocompatibility of plasma-treated silicone elastomer. The surface biocompatibility was greatly improved after modification; human skin fibroblasts adhered quickly and grew well on the modified silicone surface.

Preparation of nanocones for immobilizing DNA probe by a low-temperature plasma plume

Using allylamine monomer, a matrix of nanocones was fabricated by applying a low-temperature plasma plume without any catalysts and template. This nanocone acted as an adhesion layer immobilizing DNA probe for DNA hybridization assay. A simple conceptual model to describe the growth of the nanocones was also developed. The highest density of amino-labeled DNA probe was about 1.6pM∕cm2 confirmed by the dyed oligonucleotide, and each nanocone contained nearly 3×102 amine groups. This strategy provides a robust procedure to immobilize DNA, which is a very useful substrate for fabricating nanobiosensors.

Surface Analysis of Plasma Deposited Polymer Films, 7

AbstractSummary: Plasma deposited allylamine films were studied by “in situ” ToF‐SSIMS, XPS and NEXAFS Spectroscopy before exposure to ambient air. The influence of external plasma parameters such as duty cycle, plasma power, and monomer flow rate on (i) unsaturation, (ii) branching and cross‐linking, (iii) nitrogen surface concentration and (iv) retention of amino groups was investigated. Harder plasma conditions, which can be obtained when high duty cycles, high plasma power, and low monomer flow rates are employed, increase the unsaturated, branched and cross‐linked character of the plasma deposited films, while the surface concentration of N as well as the retention of the monomer's amino group decrease. As proven by NEXAFS findings and cross‐checked by ToF‐SSIMS results, the allylamine monomer's primary amino groups are partially transformed into other nitrogen functionalities during its plasma polymerization. Amongst them imines and nitriles are the conversion products with the highest probabilities of formation. Another conversion channel is the formation of nitrogen species not participating in the film growth. This is the reason for an increased N loss in plasma deposited allylamine films as observed independently by XPS and ToF‐SSIMS when the plasma parameters are changed from mild to hard.Summations of π*(CN) and π*(CN) resonance intensities for NEXAFS N K‐edge spectra measured with plasma deposited allylamine films vs. variation of duty cycle, or power.magnified imageSummations of π*(CN) and π*(CN) resonance intensities for NEXAFS N K‐edge spectra measured with plasma deposited allylamine films vs. variation of duty cycle, or power.

Functional Micropatterned Surfaces by Combination of Plasma Polymerization and Lift‐Off Processes

AbstractSummary: In this study, microstructured surfaces are produced by a spatial arrangement of different functional domains by a combination of plasma polymerization and photolithography. Two different kinds of protein and cell adhesive patterns have been alternated with non‐fouling areas. Non‐fouling patterns are made of poly(ethylene oxide) (PEO)‐like polymers obtained by pulsed plasma polymerization of diethylene glycol dimethyl ether, which leads to coatings with a high concentration of ethylene oxide groups (>70%). Fouling surfaces are composed of PEO coatings with a low concentration of ethylene oxide groups (≈40%) and films containing amino groups (from allylamine monomer) obtained by plasma polymerization. High pattern fidelity is demonstrated by ellispometry measurements, whereas XPS and ToF‐SIMS analyses have been used to characterize the surfaces. Experiments with a model protein (bovine serum albumin) and cells (L929 mouse fibroblasts) on patterned surfaces show that proteins and cells only adhere on the patterns, whereas the background stays uncovered.Optical image showing the selective proliferation of L929 mouse fibroblast cells after culture on a pulsed PEO‐like/PAL micropatterned surface.magnified imageOptical image showing the selective proliferation of L929 mouse fibroblast cells after culture on a pulsed PEO‐like/PAL micropatterned surface.

Plasma Polymerization of Allylamine onto Pan-Based Carbon Fibers

AbstractThe plasma polymerization of allylamine onto PAN-based carbon fibers has been investigated by XPS and SEM. Fiber surfaces were cleaned and oxidized by treating in an O2 plasma for 5 minutes. XPS characterization of pretreated samples showed surfaces functionalized with COH, C=O, and COOH species. Fibers were coated with poly(allylamine) by introducing a monomer-saturated stream of Ar gas into the plasma chamber and reacting for 2–30 minutes. Some samples were further treated in an O2 plasma to determine the stability of the polymer coating. N(1s) spectra from the fiber surfaces showed two nitrogen peaks at 399.9 eV and 400.7 eV, which may be assigned to amine and amide groups, respectively. C(1s) spectra showed a decrease with treatment in the amine carbon peak at 287.2 eV and a corresponding increase in the peak at 288.7 eV, assigned to carboxyl and/or amide carbon. The increase in higher binding energy carbon corresponded with an increase in the 400.7 eV N(1s) peak and gave evidence for the conversion of amines to amides. Total O(1s) intensity initially decreased following 2 minutes of allylamine treatment but increased with further treatment. In addition to the carbon fiber samples, a silica wafer was coated and analyzed by XPS. Quantitative XPS results revealed that all the nitrogen present on the surface was in the form of amine and not amide species. Oxygen in the form of carboxyl species was also present on coated silica surfaces. Most likely, oxygen dissolved in the allylamine monomer was carried into the plasma chamber by the Ar gas. Comparing the silica wafer with the fiber samples revealed treatments were strongly sample dependent. Even after only 2 minutes of treatment, fiber samples showed the presence of amide and substituted amide species. SEM revealed coatings filled in the fiber grooves and left clumps of material on the surface. Micrographs of fibers treated for longer times revealed surfaces covered with particles < 0.25 μm in diameter. Finally, the XPS N(1s)/C(1s) and O(1s)/C(1s) intensity ratios indicated that some polymer remained on the fiber surface even after 15 minute post O2 plasma treatment. These experiments illustrate that plasma polymerization can be effective for functionalizing carbon fiber surfaces, but that optimization of conditions is necessary to improve wetting and control amine/amide functionality.

Thermally regenerable ion-exchange resins. III filling macroporous resin with crosslinked resin

An aqueous solution of diallylamine hydrochloride and 1,6-bis(N,N-diallylamino)hexane hydrochloride was absorbed into a macroporous polyacrylic acid resin bead and polymerized by γ-irradiation to give resin beads which were hard and strong, and which had a high density, low swelling and a thermally regenerable capacity of 0.81 meq/g. On a volume basin the resin had a capacity of 0.22 meq/ml which is equal to that of the precious best resin, but the latter is physically weaker. The allylamine monomers, when absorbed into the macroporous polyacrylic acid, did not polymerize with a chemical initiator.