Cell adhesion and growth on surfaces modified by plasma and ion implantation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structural and optical properties of brominated plasma polymers

Novel brominated amorphous hydrogenated carbon (a-C:H:Br) films were produced by the plasma polymerization of acetylene-bromoform mixtures. The main parameter of interest was the degree of bromination, which depends on the partial pressure of bromoform in the plasma feed, expressed as a percentage of the total pressure, R-B. When bromoform is present in the feed, deposition rates of up to about 110 nm min(-1) may be obtained. The structure and composition of the films were characterized by Transmission Infrared Reflection Absorption Spectroscopy (IRRAS) and X-ray Photo-electron Spectroscopy (XPS). The latter revealed that films with atomic ratios Br:C of up to 0.58 may be produced. Surface contact angles, measured using goniometry, could be increased from similar to 63 degrees (for an unbrominated film) to similar to 90 degrees for R-B of 60 to 80%. Film surface roughness, measured using a profilometer, does not depend strongly on R-B. Optical properties the refractive index, n, absorption coefficient, alpha(E), where E is the photon energy, and the optical gap, E-g, were determined from film thicknesses and data obtained by Transmission Ultraviolet-Visible Near Infrared Spectroscopy (UVS). Control of n was possible via selection of R-B. The measured optical gap increases with increasing F-BC, the atomic ratio of Br to C in the film, and semi-empirical modeling accounts for this tendency. A typical hardness of the brominated films, determined via nano-indentation, was similar to 0.5 GPa. (C), 2013 Elsevier B.V. All rights reserved.

Aging of plasma-activated copper and gold surfaces and its hydrophilic recovery after water immersion

A significant increase of surface hydrophilicity of copper and gold surfaces was obtained after atmospheric pressure plasma treatment using the surface dielectric barrier discharge with specific electrode geometry, the so-called diffuse coplanar surface barrier discharge. Surface wettability was estimated using the sessile drop method with further calculation of the surface free energy. After the plasma treatments, it was observed that the treated surfaces exhibited hydrophobic recovery (or aging effect). The aging effect was studied in different storage environments, such as air, low and high vacuum. The role of plasma and the reasons of the following aging effect are discussed with respect to the observed hydrophilic recovery after immersing the aged surfaces into deionized water. The changes in the surface morphology, composition and bond structure are presented and discussed as well. (C) 2013 Elsevier B. V. All rights reserved.

Platelet-Rich Plasma, Low-Level Laser Therapy, or Their Combination Promotes Periodontal Regeneration in Fenestration Defects: A Preliminary In Vivo Study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Study of magnetic field enhanced plasma immersion ion implantation in Silicon

A comparison between experimental measurements and numerical calculations of the ion current distribution in plasma immersion ion implantation (PIII) with external magnetic field is presented. Later, Silicon samples were implanted with nitrogen ion to analyze the effect on them. The magnetic field considered is essentially non-uniform and is generated by two magnetic coils installed on vacuum chamber. The presence of both, electric and magnetic field in PIII create a crossed ExB field system, promoting drift velocity of the plasma around the target. The results found shows that magnetized electrons drifting in ExB field provide electron-neutral collision. The efficient ionization increases the plasma density around the target where a magnetic confinement is formed. As result, the ion current density increases, promoting significant changes in the samples surface properties, especially in the surface wettability.

Effect of Silver Nanoparticles in a Hydroxyapatite Coating applied by Atmospheric Plasma Spray

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Amorphous silicon carbonitride films modified by plasma immersion ion implantation

Amorphous silicon carbonitride (a-SiCN:H) films were deposited from hexamethyldisilazane (HMDSN) organic compounds via radio-frequency (RF) glow discharges. Afterwards the films were bombarded, from 15 to 60 min, with nitrogen ions using Plasma Immersion Ion Implantation (PIII) technique. X-ray photoelectron spectroscopy (XPS) showed that O-containing groups increased, while C-C and/or C-H groups decreased with treatment time. This result indicates chemical alterations of the polymeric films with the introduction of polar groups on the surface, which changes the surface wettability. In fact, the hydrophobic nature of a-SiCN:H films (contact angle of 100 degrees) was changed by nitrogen ion implantation and, and after aging in atmosphere air, all samples preserved the hydrophilic character (contact angle <80 degrees) independently of treatment time. The exposure of the films to oxygen plasma was performed to evaluate the etching rate, which dropped from 24% to 6% while the implantation time increased from 15 to 60 min. This data suggests that Pill increased the film structure strength, probably due to crosslinking enhancement of polymeric chains. Therefore, the treatment with nitrogen ions via Pill process was effective to modify the wettability and oxidation resistance of a-SiCN:H films. (C) 2014 Elsevier Ltd. All rights reserved.

Acetylene plasma polymer treated by atmospheric dielectric barrier discharge

Plasma polymer films are very attractive for industrial applications in several sectors such as in the electronic, mechanic, biomedic, coating and others, due to its good adhesion, being insoluble in mild acids and bases and having a high crosslinking structure. This work reports the physical, structural, and surface properties of the polymer obtained from an acetylene plasma polymerization technique and treated by dielectric barrier discharge (DBD). The film was deposited in a reactor supplied by a radio-frequency power source at low pressure. After deposition, the nanofilms were treated in a DBD plasma reactor operating in air. The treatment times varied from 1 to 5 min. The analysis of molecular structure of the samples was investigated by FTIR spectroscopy, showing absorption bands in 3480, 2930, 1720, 1450 and 1380 cm(-1). The water contact-angle was investigated by goniometric technique and presented values from 5 to 65 degrees. The aging effect of these films was also studied. The alteration in the films surface morphology was assessed by an atomic force microscopy (AFM) which indicated that the roughness increased from 60 nm to 160 nm as a result of the DBD treatment. The refractive index of the samples presented values near 1.7, measured by UV-Visible spectroscopy. (C) 2014 Elsevier Ltd. All rights reserved.

Cell Adhesion to Plasma-Coated PVC

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Platelet-Rich Plasma Derived From Bone Marrow Aspirate Promotes New Cementum Formation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Implantação iônica por imersão em plasma e deposição de filmes finos poliméricos provenientes da mistura hexametildisilazano/argônio

Thin polymeric films deposited by plasma are very atractive for many industrial and scientific applications, in areas such as electronics, mechanics, coatings, biomaterials, among others, due to its favorable properties such as good adhesion to the substrate, high crosslinking, nanomectric thickness, homogeneity, etc. In this work, thin films were deposited by plasma immersion ion implantation and deposition technique from a hexamethyldisilazane/argon mixture at different proportions. These films were subjected to several characterizations, such as, contact angle, which presented values near to 100 degrees, surface energy, with values near to 31 mJ/m2, hardness with values between 0.7 and 2.6 GPa, thickness from 100 to 200 nm, refractive index from 1.56 to 1.64, molecular structure presenting the following functional groups in the infrared spectra region: CHx from 2960 to 2900 cm-1; Si-H around 2130 cm-1; CH3 in Si-(CH3)x around 1410 cm-1; CH3 in Si-(CH3)x in 1260 cm-1; N-H around 1180 cm-1; CH2 in Si-CH2-Si bonds around 1025 cm-1; Si-O in Si-O-Si from 1020 to 1100 cm-1; Si-N in Si-H-Si bonds around 940 cm-1; CH3 in Si-(CH3)3 in 850 cm-1; Si-C bonds in Si-(CH3)2 around 800 cm-1; and Si-H in 680 cm-1 . From these characterizations, it was possible to conclude that the concentration of argon or hexamethyldisilazane in the mixture changed the resulting polymer

Tratamento da superfície do alumínio via eletrólise a plasma

This paper presents the study on the application of the electrolytic plasma for surface treatment of aluminum. A bibliographical study on the material of interest was preliminarily performed and later designed and built an electrolytic cell, including the excitation source. Unlike conventional electrolysis process, the plasma assisted carry on in the non-linear region of characteristic current/voltage curve. Therefore it requires for the on set of the process that the power supply operates on harder conditions than those on high current process. The plasma produced during the present investigation has temperatures in the range o 6,0.10 3 -7,0 .10 3 K, well above those found in conventional chemical process. It also shows a particular dynamic to promote changes on surface and to produce new materials. The plasma is generated by microdischarge in vapor or gas bubbles involved in physic-chemical processes in electrode regions of the electrolytic cell. The electrode material was the aluminum (7075). The Process Electrolytic Plasma Processing (EPP) is sensitive to various parameters such as operating voltage, current density, electrolyte, concentration of electrolyte, geometry of reactor, temperature of electrolytic solution and dynamic of the fluid in the cell. The experiments were carried on in order to find parameters for a stable abd steady operation. The choice for the electrolytic was silicate/alkali solution in various concentrations to operate in various voltage as well. Plasma was produced on negative (cathode) and positive (anode) electrode, in specific conditions. A stable operation on the cathode process was obtained with low concentration of the electrolytic in aqueous solution, current density around 250V effective voltage. For the evolution of plasma in anodic process it was required higher concentrations and higher... (Complete abstract click electronic access below)

Fadiga axial do aço inoxidável 15-5 PH tratado pela implantação iônica por imersão em plasma

When materials for application in aircraft structural components are studied, it must be considered that they will be submitted to cyclic loading, and this is an important parameter to design the study in fatigue life of the materials. Whereas, for example, a landing gear operation, the study of fatigue life and corrosion in the materials used in it is essential, especially when you want to use new techniques for surface treatments. The objective is to study the influence of surface treatment of immersion ion implantation nitrogen plasma, in axial fatigue of Stainless steel 15-5 PH in 39-42 HRC condition. Stainless steel 15-5 PH was tested in axial fatigue and corrosion in salt spray. It was also performed microindentation tests, optical microscopy for microstructural analysis and scanning electron microscopy for fractographic analysis. It was observed that the 3IP had no effect on the thickness of the material and not the hardness of it, and still provided a significant increase in fatigue life of the material

Estudo comparativo da utilização de PRP (Plasma Rico em Plaquetas) autólogo na cicatrização de feridas metacarpianas em equinos: aspectos macroscópicos, histopatológicos, imunoistoquímicos e morfométricos

Pós-graduação em Medicina Veterinária - FMVZ

Estudo da modificação superficial de fibras de carbono por meio de tratamentos a plasma para o aumento da adesão na interface de compósitos fibra de carbono/PPS

Pós-graduação em Engenharia Mecânica - FEG