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At least 19 recordsLinked to original sources
PubMed2005

[Effect of surface modification on surface energy of lactose and performance of dry powder inhalations].

AIM: To investigate the effects of surface modification of lactose carrier on performance of dry powder inhalations (DPIs). METHODS: Modified lactose surface was prepared using a "particle smoothing" process to obtain smooth carrier surface and low surface energy with the presence of magnesium stearate, colloidal silica dioxide and talc. Inverse gas chromatography (IGC) was used to assess the surface energy of treated lactose, and the in vitro deposition of carrier-based IFNa-2b DPIs was evaluated with twin stage impinger. RESULTS: The flowing property of lactose was greatly improved and the surface energy decreased by the "particle smoothing" process. Decreasing surface energy resulted in greater aspiration fraction of IFNa-2b. CONCLUSION: IGC is a potentially useful tool for rapid formulation design and screening.

Administration, Inhalation↗
PubMed2005

Surface modification of surface sol-gel derived titanium oxide films by self-assembled monolayers (SAMs) and non-specific protein adsorption studies.

Biological events occurring at the implant-host interface, including protein adsorption are mainly influenced by surface properties of the implant. Titanium alloys, one of the most widely used implants, has shown good biocompatibility primarily through its surface oxide. In this study, a surface sol-gel process based on the surface reaction of metal alkoxides with a hydroxylated surface was used to prepare ultrathin titanium oxide (TiOx) coatings on silicon wafers. The oxide deposited on the surface was then modified by self-assembled monolayers (SAMs) of silanes with different functional groups. Interesting surface morphology trends and protein adhesion properties of the modified titanium oxide surfaces were observed as studied by non-specific protein binding of serum albumin. The surface properties were investigated systematically using water contact angle, ellipsometry, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) measurements. Results showed that the surface sol-gel process predominantly formed homogeneous, but rough and porous titanium oxide layers. The protein adsorption was dependent primarily on the silane chemistry, packing of the alkyl chains (extent of van der Waals interaction), morphology (porosity and roughness), and wettability of the sol-gel oxide. Comparison was made with a thermally evaporated TiOx-Ti/Si-wafer substrate (control). This method further extends the functionalization of surface sol-gel derived TiOx layers for possible titanium alloy bioimplant surface modification.

Adsorption↗
PubMed2002

Surface modification of montmorillonite on surface Acid-base characteristics of clay and thermal stability of epoxy/clay nanocomposites.

In this work, the effect of surface treatments on smectitic clay was investigated in surface energetics and thermal behaviors of epoxy/clay nanocomposites. The pH values, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) were used to analyze the effect of cation exchange on clay surface and the exfoliation phenomenon of clay interlayer. The surface energetics of clay and thermal properties of epoxy/clay nanocomposites were investigated in contact angles and thermogravimetric analysis (TGA), respectively. From the experimental results, the surface modification of clay by dodecylammonium chloride led to the increases in both distance between silicate layers of about 8 A and surface acid values, as well as in the electron acceptor component (gamma(+)(s)) of surface free energy, resulting in improved interfacial adhesion between basic (or electron donor) epoxy resins and acidic (electron acceptor) clay interlayers. Also, the thermal stability of nanocomposites was highly superior to pure epoxy resin due to the presence of the well-dispersed clay nanolayer, which has a barrier property in a composite system.

Journal Article↗
PubMed1992

A brief introduction to advanced surface modification technologies.

Techniques for the modification of surfaces are evolving rapidly. In implantology, few of the newer surface modification techniques have been used. The purpose of this paper is to provide an introduction to advanced surface modification processes that could be useful in dental implant manufacturing. There are three general techniques used to modify surfaces: add material, remove material, and change the material already present. Several processes for the addition of material to surfaces are described in this paper. Two new processes that can create relatively thick coatings are sol-gel and plasma-spraying. Several new processes making thin film coatings (sub-micron) have come from the electronics and optics industries. These are vapor deposition techniques, where the coating material condenses onto a surface from a vapor. The three basic vapor deposition techniques are: evaporation, sputtering, and chemical vapor deposition. New processes for the removal of material from surfaces, often for cleaning purposes, are glow discharge treatment and sputter-etching. Surface properties can also be changed without addition or removal of material by use of laser and electron beam thermal treatments. Ion implantation can be used to add material to surfaces, modify coatings, and change microstructures. The techniques outlined in this paper have great potential for improving implants.

Dental Implants↗
PubMed2007

Effect of sequential layer-by-layer surface modifications on the surface energy of plasma-modified poly(dimethylsiloxane).

Surface-initiated grafting of N,N-dimethylacrylamide, styrenesulfonate (SS), and (ar-vinylbenzyl)trimethylammonium chloride (VBTAC) from microwave plasma carboxylated, initiator-functionalized poly(dimethylsiloxane) (PDMS) surfaces was accomplished utilizing reversible addition-fragmentation chain transfer (RAFT) polymerization. Surface spectroscopic attenuated total reflectance (ATR) FT-IR analysis and atomic force microscopy (AFM) measurements were utilized to determine surface grafting and morphological surface features. The VBTAC-grafted PDMS provided a smooth, hydrophilic cationic surface for creating layer-by-layer (LBL) surfaces via alternating deposition of well-defined poly(SS) and poly(VBTAC), also prepared via aqueous RAFT. Comparisons of the ATR FT-IR spectra of the LBL assemblies and those of respective anionic poly(SS) and cationic poly(VBTAC) components confirmed strong electrostatic complexation of a fraction of the sulfonate and quarternary ammonium species in the layers as well as the existence of noncomplexed species. AFM images of surface topology indicated the presence of domains, likely phase-separated segments of the respective homopolymers, as well as interlayer mixing. The employed LBL methodology results in formation of stable, highly hydrophilic surfaces on a PDMS substrate. To our knowledge, this is the first study that illustrates surface functionalization of PDMS using microwave plasma and RAFT polymerization, followed by LBL deposition of polyelectrolytes.

Journal Article↗
PubMed1992

The effects of heparin bound surface modification (Carmeda Bioactive Surface) on human platelet alterations during simulated extracorporeal circulation.

To determine if treatment with covalently bound heparin (Carmeda Bioactive Surface (CBAS)) to the synthetic surface of the extracorporeal circuit (ECC) would alter the stereotypic pattern of adverse platelet alterations, 450 ml of heparinized blood (lU/ml) was recirculated at a flow rate of twice the circulating volume (L/min) for 2 hrs at 37 degrees C through either untreated (CONT,n=7) or treated (CBAS,n=7) circuits constructed of identical components including a pediatric (0.8m 2) reversed hollow fiber membrane oxygenator. In CONT circuits, platelet count maintained 88+1% (x+/-SEM) of its initial level in the circuit prime sample, dropped to 36+/-6% after 5 min, and returned to 56+/-2% following 2 hrs of ECC. In CBAS circuits, platelet count in the circuit prime sample demonstrated 90+/-4%, decreased to 68+/-10% after 5 min (p less than 0.05) and declined further to 45+/-5% after 2 hrs (NS). Although platelets from both groups retained reactivity to ADP after priming the circuit, only at 5 min of recirculation did CBAS circuits significantly preserve this responsiveness. In CONT circuits, baseline plasma levels of platelet factor 4 rose from 24+/-3 to 581+/-82 ng/ml in the primed circuit and continued to rise to 2933+/-276 ng/ml by 2 hrs of ECC. In contrast, CBAS circuits markedly reduced this release after 2 hrs (577+/-165 ng/ml). Furthermore by 2 hrs of ECC, plasma levels of thromboxane B 2 in the CBAS circuits were significantly reduced when compared to CONT circuits (3035+/-1529 vs 29916+/-16293 pg/ml, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed2005

Review paper: surface modification for bioimplants: the role of laser surface engineering.

Often hard implants undergo detachment from the host tissue due to inadequate biocompatibility and poor osteointegration. Changing surface chemistry and physical topography of the surface influences biocompatibility. At present, the understanding of biocompatibility of both virgin and modified surfaces of bioimplant materials is limited and a great deal of research is being dedicated to this aspect. In view of this, the current review casts new light on research related to the surface modification of biomaterials, especially materials for prosthetic applications. A brief overview of the major surface modification techniques has been presented, followed by an in-depth discussion on laser surface modifications that have been explored so far along with those that hold tremendous potential for bioimplant applications.

Biocompatible Materials↗
PubMed1995

Surface modification of polymers: chemical, biological and surface analytical challenges.

Surface modification methods can optimise the biocompatibility or the specificity of biointeraction of a biosensor or medical device. With only the surface modified, the manufacture and implantation protocol remain unchanged. This review article summarises some of the chemical, surface analytical and biological challenges associated with surface modification of biosensors and biomedical devices.

Biocompatible Materials↗
PubMed1999

A new advanced surface modification technique--titanium oxide ceramic surface implants: the background and long-term results.

This paper discusses the background of advanced surface modification technologies and presents a new technique that forms a titanium oxide ceramic coating with relatively long-term clinical use. Three general techniques are used to modify surfaces: adding or removing material, or changing material already present. Surface properties can also be changed through laser or electron beam thermal treatment without adding or removing material. The new technique outlined in this paper describes producing a corrosion-resistant, 2000 A to 2500 A thick, coherent crystalline oxide ceramic layer on the surface of titanium implants. The layer is grown electrochemically from the bulk of the metal and modified by heat treatment. Compared with implants covered with other coatings, the improved properties of such oxide ceramic-coated implants include the advantages of higher external hardness and greater adherence between the titanium and the ceramic oxide coating. The virtually perfect insulation between the tissue and the metal prevents metal allergy. The coated implants were subjected to various physical and chemical tests and electron microscopy for a qualitative characterization. Finally, these implants (plates, screws for maxillofacial osteosynthesis, and dental root implants) were followed in surgical practice for 10 years. Tests demonstrated and the acquired experience confirmed the good properties of the titanium oxide ceramic-coated implants.

Ceramics↗
PubMed2005

Electron injection into the surface states of ZrO2 nanoparticles from photoexcited quinizarin and its derivatives: effect of surface modification.

The effect of surface modification on interfacial electron transfer (IET) dynamics into the surface states of ZrO(2) nanoparticles sensitized by quinizarin (Qz) and its derivatives has been carried out using time-resolved emission spectroscopy. The surface of ZrO(2) nanoparticles has been modified by sodium dodecyl benzyl sulfonate . We have observed that Qz's can form a strong charge-transfer (CT) complex with both unmodified and surface-modified (SM) ZrO(2) nanoparticles. We have confirmed electron injection into the surface states of ZrO(2) nanoparticles from the photoexcited Qz molecule in our earlier work (J. Phys. Chem. B 2004, 108, 4775; Langmuir 2004, 20, 7342). In the present investigation, we have observed electron injection from photoexcited Qz derivatives into the surface states of both unmodified and SM ZrO(2) nanoparticles and also detected CT emission. Monitoring CT emission, we have determined back electron transfer (BET) dynamics of the dye-nanoparticle systems. We have found that the BET rate for the QZs/ZrO(2) systems decreases as the relative driving force increases following Marcus inverted region kinetic behavior for an IET process. BET dynamics was found to be faster on SM ZrO(2) nanoparticles as compared to that of the unmodified (bare) one. Our time-resolved emission data indicates that upon surface modification the majority of the deeper trap states of ZrO(2) nanoparticles can be removed with the formation of some new shallower trap states in the band gap region.

Journal Article↗
PubMed2005

Surface modification and functionalization through the self-assembled monolayer and graft polymerization.

The modification of a surface at the molecular level with precise control of the building blocks generates an integrated molecular system. This field has progressed rapidly in recent years through the use of self-assembled monolayer (SAM) interfaces. Recent developments on surface-initiated chemical reactions, functionalization, and graft polymerization on SAM interfaces are emphasized in the present review. A number of surface modifications by grafting are reviewed. The grafting of polyaniline on a glass surface, previously modified with a silane self-assembled monolayer (SAM), is examined in detail for both planar and 3-D systems, such as fibers, nanoparticles, and even polymer patterned surfaces. We also discuss the graft polymerization of water-soluble polymers on the surface of silicon nanoparticles, which generate stable aqueous colloidal solutions and have numerous applications. Finally, we compare and review some surface-modification techniques on the surfaces of polymers, such as two-solvent entrapment, polymer blending, and chemical grafting, which improve their biocompatibility.

Aniline Compounds↗
PubMed2004

Improvement in the luminescence properties and processability of LaF3/Ln and LaPO4/Ln nanoparticles by surface modification.

The surface of lanthanide(III)-doped LaPO4 nanoparticles was modified by reaction with an alcohol, leading to a covalent bond between the ligand and the particle surface. The surface of lanthanide(III)-doped LaF3 nanoparticles was modified to alter the solubility of the nanoparticles and study the influence of surface effects on the luminescence of lanthanide ions doped in the nanoparticles. The coordinated organic ligands can be modified by a quantitative exchange reaction in solution or by using functionalized ligands during the synthesis. Variation of the ratio of ligand to core reagents had a significant influence on the size of the nanoparticles. Smaller nanoparticles were formed with a higher ligand ratio. The optical properties of these nanoparticles show a strong dependence on nanoparticle size, indicating the influence of quenching probably by CH and OH groups at or near the surface of the nanoparticle cores. The luminescence lifetime of LaF3/Eu nanoparticles varied from 6.5 to 7.4 ms for nanoparticles with an average size of 7.1 to 8.4 nm. A significant reduction of the quenching from the surface of the nanoparticles was obtained by the synthesis of core-shell nanoparticles, in which a shell of LaF3 was grown epitaxially around the doped core nanoparticles. This leads to an increase in the luminescence lifetime of the Eu3+ ion and the observation of emissions from the 5D2 energy level, in addition to emissions from the 5D1 and 5D0 levels. The quantum yield of LaF3/Ce,Tb nanoparticles could be increased from 24 to 54% by the growth of a LaF3 shell around the nanoparticles.

Journal Article↗
PubMed2002

Water-soluble and optically pH-sensitive single-walled carbon nanotubes from surface modification.

There is great interest in using single-walled carbon nanotubes (SWNTs) as nanoscale probes and sensors in biological electronics and optical devices because the electronic and optical properties of SWNTs are extremely sensitive to the surrounding environments. A well-controlled modification of SWNT surfaces may provide unique interfaces that are sensitive to the biological variables such as pH, glucose, various ions and proteins. In this paper, we report a facile chemical routine to prepare water-soluble SWNTs that still retain their van Hove singularities after acid oxidative treatment. The aqueous solutions (0.03-0.15 mg/mL) are stable for more than a month. The solubility in water for as-treated SWNTs with surfaces modified by carboxylate groups provides us with a unique opportunity to reveal the relationship of the SWNT electronic and optical properties with pH. Here we present the first observation that after surface modification with carboxylate groups, the optical absorption of the first interband transition of as-treated water-soluble semiconducting SWNTs reversibly responds to the pH change in aqueous solutions. Our results indicate that surface modification of SWNTs is a promising way for preparing chemically selective SWNT interfaces, which may open new exciting opportunities for various applications.

Biosensing Techniques↗
PubMed2003

Wavelength and average power density dependency of the surface modification of root dentin using an MIR-FEL.

BACKGROUND AND OBJECTIVES: Surface modification of root dentin by mid-infrared (MIR) pulsed-laser irradiation is one of the candidates for a novel, non-invasive treatment to prevent root surface caries. To modify root dentin effectively and non-invasively it is essential to estimate quantitatively and qualitatively the laser parameters, such as the wavelength and power density, required for surface modification. The key aspect is to bring about effective surface modification of the root dentin while minimizing the unwanted removal of the underlying dentin. STUDY DESIGN/MATERIALS AND METHODS: Using a tunable, MIR Free Electron Laser with lambda = 8.8-10.6 microm, we have investigated macroscopically the extent of the surface modification (morphological and chemical changes) of root dentin. We have obtained experimental results related to the ablation depth, the MIR absorption spectrum, and the elemental chemical composition. RESULTS: The observations showed that the surface modification of root dentin was inclined toward well-recrystallized HAp-like material, leading to an increase in the acid resistance and dentinal tubule sealing. The laser parameters, at which efficient surface modification without enhanced ablation occurred, were estimated to be approximately in the wavelength region around lambda = approximately 9.0 or approximately 9.7 microm and in the average power density region of approximately 10-20 W/cm2 (resulting in total energy density and peak power density regions of approximately 1-2 kJ/cm2 and approximately 0.67-1.2 kW/cm2). CONCLUSIONS: The surface modification of root dentin strongly depends on the laser parameters applied. We conclude that the optimum wavelengths for laser treatment of root surface caries are lambda = approximately 9.0 or approximately 9.7 microm, corresponding to the absorption peak due to P-O stretching.

Animals↗
PubMed2002

Influence of 30% hydrogen peroxide bleaching on compomers in their surface modifications and thermal expansion.

The surface modifications and the coefficient of thermal expansion of compomers after treatment with a 30% hydrogen peroxide bleaching agent were investigated. Three compomers (Compoglass F, Elan and F2000) were nonbleached and bleached for 1 and 3 days. The surface modification and the coefficient of thermal expansion of each bleached compomer were evaluated using a scanning electron microscope and a thermomechanical analyzer, respectively. As a result, Compoglass F and Elan showed slight surface degradation, whereas F2000 showed many cracks on its surface and these cracks were not observed in Compoglass F and Elan. Bleached Elan and F2000 has changed to the extent where their the coefficient of thermal expansion increased compared with those of nonbleached specimens. In addition, bleached compomers showed a strong inverse correlation between the coefficient of thermal expansion and the volume percent of filler.

Analysis of Variance↗
PubMed2004

Surface modification of nanoporous alumina surfaces with poly(ethylene glycol).

Nanoporous alumina surfaces have a variety of applications in biosensors, biofiltration, and targeted drug delivery. However, the fabrication route to create these nanopores in alumina results in surface defects in the crystal lattice. This results in inherent charge on the porous surface causing biofouling, that is, nonspecific adsorption of biomolecules. Poly(ethylene glycol) (PEG) is known to form biocompatible nonfouling films on silicon surfaces. However, its application to alumina surfaces is very limited and has not been well investigated. In this study, we have covalently attached PEG to nanoporous alumina surfaces to improve their nonfouling properties. A PEG-silane coupling technique was used to modify the surface. Different concentrations of PEG for different immobilization times were used to form PEG films of various grafting densities. X-ray photoelectron spectroscopy (XPS) was used to verify the presence of PEG moieties on the alumina surface. High-resolution C1s spectra show that with an increase in concentration and immobilization time, the grafting density of PEG also increases. Further, a standard overlayer model was used to calculate the thickness of PEG films formed using the XPS intensities of the Al2p peaks. The films formed by this technique are less than 2.5 nm thick, suggesting that such films will not clog the pores which are in the range of 70-80 nm.

Adsorption↗
PubMed1999

Physical polymer surface modification methods and applications in food packaging polymers.

Continued innovations in the polymer industry have made polymer surface modification methods a subject of intense research. The importance and necessity of surface modification of plastics are explained, and the advantages of physical surface treatments over the less-sophisticated chemical methods are outlined. Currently available physical surface modification methods for food packaging polymers are reviewed from the food packaging perspective. These physical surface modification methods include flame, corona discharge, UV, gamma-ray, electron beam, ion beam, plasma, and laser treatments. The principle of operation of each method is briefly described, and the advantages and disadvantages of each technique are cited. The extent to which each of these methods can produce the specific modifications desired is discussed. Furthermore, the effects of each treatment on barrier, mechanical, and adhesion properties of food packaging polymers are also examined. Finally, an overview of economic aspects of sophisticated surface modification techniques, including ion beam, plasma, and laser treatments, is presented.

Food Packaging↗
PubMed2000

Influence of surface modifications to titanium on oral bacterial adhesion in vitro.

The influence of surface modifications to titanium on the initial adherence of Porphyromonas gingivalis ATCC33277 and Actinobacillus actinomycetemcomitans ATCC43718 was evaluated. Surface modifications were performed with dry processes including ion implantation (Ca(+), N(+), F(+)), oxidation (anode oxidation, titania spraying), ion plating (TiN, alumina), and ion beam mixing (Ag, Sn, Zn, Pt) with Ar(+) on polished pure titanium plates. Comparatively large amounts of P. gingivalis and A. actinomycetemcomitans adhered to polished titanium plates. The degree of P. gingivalis adhesion showed a positive correlation with surface energy and the amount of calcium-ion adsorption. Adherence of both P. gingivalis and A. actinomycetemcomitans increased on calcium-implanted surfaces compared with polished titanium surfaces, whereas adherence of P. gingivalis was remarkably decreased on alumina-coated surfaces. These findings indicate that titanium implants exposed to the oral cavity require surface modification to inhibit the adherence of oral bacteria, and that surface modification with a dry process is useful in controlling the adhesion of oral bacteria as well as ensuring resistance against wear.

Aggregatibacter actinomycetemcomitans↗