Plasma-polymerized Ethylenediamine Research Articles

Ciprofloxacin‐Loaded Ceramic/Polymer Composite Coatings on Ti with Improved Antibacterial and Corrosion Resistance Properties for Orthopedic Applications

AbstractPast few decades witnessed the upcoming of osteomyelitis which is a challenging infectious bone disease. Complications related to this infection is encountered by local drug delivery via orthopedic surgery. In this work, TiO2‐SiO2 based bioceramics coatings were fabricated on Ti alloy by anodization method using sulphuric acid and Sodium silicofluoride (SSF) as an electrolyte. Plasma polymerized ethylenediamine (PPEDA) thin film deposited on composites by inductively coupled plasma chemical vapor deposition and followed by ciprofloxacin were used as a model drug by electrodeposition method. The resultant coatings were characterized by FTIR, XRD, FESEM, EDAX and AFM techniques. The mechanical behavior of the composite coatings was evaluated using thickness and hardness tester and electrochemical properties were studied in Ringer's solution. Similarly, CIP@PPEDA/TiO2‐SiO2 composite coating on Ti alloy shows good corrosion resistance and better antibacterial efficacy as well as L929 fibroblast cell line, which exhibited a high cell adhesion and high cell viability compared than TiO2‐SiO2 and PPEDA/TiO2‐SiO2 coatings. All these results suggest that, this newly developed composite coating exhibits superior bioactivity and improved anticorrosion performance on Ti specimen and can be a potential candidate for orthopedic applications.

Quantification of osseointegration of plasma-polymer coated titanium alloyed implants by means of microcomputed tomography versus histomorphometry.

A common method to derive both qualitative and quantitative data to evaluate osseointegration of implants is histomorphometry. The present study describes a new image reconstruction algorithm comparing the results of bone-to-implant contact (BIC) evaluated by means of µCT with histomorphometry data. Custom-made conical titanium alloyed (Ti6Al4V) implants were inserted in the distal tibial bone of female Sprague-Dawley rats. Different surface configurations were examined: Ti6Al4V implants with plasma-polymerized allylamine (PPAAm) coating and plasma-polymerized ethylenediamine (PPEDA) coating as well as implants without surface coating. After six weeks postoperatively, tibiae were explanted and BIC was determined by µCT (3D) and afterwards by histomorphometry (2D). In comparison to uncoated Ti6Al4V implants demonstrating low BIC of 32.4% (histomorphometry) and 51.3% (µCT), PPAAm and PPEDA coated implants showed a nonsignificant increase in BIC (histomorphometry: 45.7% and 53.5% and µCT: 51.8% and 62.0%, resp.). Mean BIC calculated by µCT was higher for all surface configurations compared to BIC detected by histomorphometry. Overall, a high correlation coefficient of 0.70 (p < 0.002) was found between 3D and 2D quantification of BIC. The μCT analysis seems to be suitable as a nondestructive and accurate 3D imaging method for the evaluation of the bone-implant interface.

Evaluation of Osseointegration of Titanium Alloyed Implants Modified by Plasma Polymerization

By means of plasma polymerization, positively charged, nanometre-thin coatings can be applied to implant surfaces. The aim of the present study was to quantify the adhesion of human bone cells in vitro and to evaluate the bone ongrowth in vivo, on titanium surfaces modified by plasma polymer coatings. Different implant surface configurations were examined: titanium alloy (Ti6Al4V) coated with plasma-polymerized allylamine (PPAAm) and plasma-polymerized ethylenediamine (PPEDA) versus uncoated. Shear stress on human osteoblast-like MG-63 cells was investigated in vitro using a spinning disc device. Furthermore, bone-to-implant contact (BIC) was evaluated in vivo. Custom-made conical titanium implants were inserted at the medial tibia of female Sprague-Dawley rats. After a follow-up of six weeks, the BIC was determined by means of histomorphometry. The quantification of cell adhesion showed a significantly higher shear stress for MG-63 cells on PPAAm and PPEDA compared to uncoated Ti6Al4V. Uncoated titanium alloyed implants showed the lowest BIC (40.4%). Implants with PPAAm coating revealed a clear but not significant increase of the BIC (58.5%) and implants with PPEDA a significantly increased BIC (63.7%). In conclusion, plasma polymer coatings demonstrate enhanced cell adhesion and bone ongrowth compared to uncoated titanium surfaces.

Aging effects of plasma polymerized ethylenediamine (PPEDA) thin films on cell-adhesive implant coatings

Thin plasma polymer films from ethylenediamine were deposited on planar substrates placed on the powered electrode of a low pressure capacitively coupled 13.56MHz discharge. The chemical composition of the plasma polymer films was analyzed by Fourier Transform Infrared Reflection Absorption Spectroscopy (FT-IRRAS) as well as by X-ray photoelectron spectroscopy (XPS) after derivatization of the primary amino groups. The PPEDA films undergo an alteration during the storage in ambient air, particularly, due to reactions with oxygen. The molecular changes in PPEDA films were studied over a long-time period of 360days. Simultaneously, the adhesion of human osteoblast-like cells MG-63 (ATCC) was investigated on PPEDA coated corundum blasted titanium alloy (Ti-6Al-4V), which is applied as implant material in orthopedic surgery. The cell adhesion was determined by flow cytometry and the cell shape was analyzed by scanning electron microscopy. Compared to uncoated reference samples a significantly enhanced cell adhesion and proliferation were measured for PPEDA coated samples, which have been maintained after long-time storage in ambient air and additional sterilization by γ−irradiation.

Optimization of Plasma Polymerized Ethylenediamine Film Chemistry on Quartz Particles

Ethylenediamine plasma polymerization has been investigated to modify the surface of quartz particles to optimize the nitrogen concentration of coatings produced via a rotating barrel plasma reactor. Plasma polymerized ethylenediamine (ppED) films were deposited at varying powers, flow rates, and polymerization times. X-ray photoelectron spectroscopy indicated that plasma power appeared to have little effect on ppED chemistry while increasing the ethylenediamine flow rate and polymerization time increased the nitrogen concentration due to reduced fragmentation and increased film thickness respectively. Time of flight secondary-ion mass spectrometry demonstrated uniform distribution of nitrogen species across the particle surface. Ethylenediamine plasma polymerization using a rotating plasma reactor has shown to be a successful method for producing nitrogen rich particle coatings.

Plasma polymerization in a microcapillary using an atmospheric pressure dielectric barrier discharge

Atmospheric pressure plasma deposition is a beneficial technology due to its low cost and flexibility in terms of its operation and integration for in-line processing. This paper presents the use of an atmospheric pressure dielectric barrier discharge (DBD) to deposit an amine functional polymer film onto the inner surface of a glass microcapillary. A micro discharge was generated in a DBD chip made from a rectangular borosilicate glass capillary using externally attached parallel plate electrodes. A new microplasma configuration which consists of a perforated high voltage electrode and a ground electrode with large surface area is implemented to sustain a stable glow discharge at atmospheric pressure and a temperature of 35°C. Polymerization was performed using a laboratory made plasma source working at a frequency of 8kHz with 50% duty ratio of the inverter. The monomer precursors allylamine and ethylenediamine were selected to optimize the polymerization conditions at atmospheric pressure. The hydrophobicity and philicity of the deposited surface were controlled as functions of plasma power. The atmospheric pressure plasma polymerized (APPP) films were characterized using Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM), plasma emission spectroscopy, contact angle measurements and growth rate analysis. An average growth rate of 1.18μgs−1 for plasma polymerized ethylenediamine (PPEDA) and 1.91μgs−1 for plasma polymerized allylamine (PPAA) was obtained at a discharge power of 15W and 10sccm of monomer flow rate. The film thickness of 0.9μm for PPEDA and 2.1μm for PPAA was determined using AFM for deposition time of 10min. Polymerization results showed that the properties of APPP films can be controlled through optimization of parameters such as discharge power, treatment time and flow rates of the main gas and monomer vapors.

In vivo examination of the local inflammatory response after implantation of Ti6Al4V samples with a combined low-temperature plasma treatment using pulsed magnetron sputtering of copper and plasma-polymerized ethylenediamine

Copper (Cu) could serve as antibacterial coating for Ti6Al4V implants. An additional cell-adhesive layer might compensate Cu cytotoxicity. This study aimed at in vitro and in vivo evaluation of low-temperature plasma treatment of Ti6Al4V plates with Ti/Cu magnetron sputtering (Ti6Al4V-Ti/Cu), plasma-polymerized ethylenediamine (Ti6Al4V-PPEDA), or both (Ti6Al4V-Ti/Cu-PPEDA). Ti6Al4V-Ti/Cu and Ti6Al4V-Ti/Cu-PPEDA had comparable in vitro Cu release and antibacterial effectiveness. Following intramuscular implantation of Ti6Al4V-Ti/Cu, Ti6Al4V-PPEDA, Ti6Al4V-Ti/Cu-PPEDA and Ti6Al4V controls for 7, 14 and 56 days with 8 rats/day, peri-implant tissue was immunohistochemically examined for different inflammatory cells. Ti6Al4V-PPEDA had more mast cells and NK cells than Ti6Al4V, and more tissue macrophages, T lymphocytes, mast cells and NK cells than Ti6Al4V-Ti/Cu-PPEDA. Ti6Al4V-Ti/Cu had more mast cells than Ti6Al4V and Ti6Al4V-Ti/Cu-PPEDA. Results indicate that PPEDA-mediated cell adhesion counteracted Cu cytotoxicity. Ti6Al4V-Ti/Cu-PPEDA differed from Ti6Al4V only for mast cells on day 56. Altogether, implants with both plasma treatments had antibacterial properties and did not increase inflammatory reactions.

Plasma processes for cell-adhesive titanium surfaces based on nitrogen-containing coatings

Differently deposited amino functionalized surfaces were compared regarding their physico-chemical surface properties in connection with cell biological response. The nitrogen containing coatings were prepared on polished titanium alloy substrates by microwave or radio frequency discharges using allylamine and ethylenediamine as precursors, respectively, or by means of radio frequency magnetron sputtering of nylon 6.6 under N2/H2 1:1 gas mixture. The chemical composition of the deposited films was determined by FT-IR and XPS analyses. Closed pinhole-free polymer films resistant to hydrolysis and delamination were detected in most cases. Advantageous medium hydrophilicities exist. The density of primary amino groups NH2/C differs on plasma polymerized allylamine (2.5%), and plasma polymerized ethylenediamine (3.7%) from the value on plasma sputtered nylon films in N2/H2 1:1atmosphere (7.2%), determined after preparation. The positively charged surfaces improve adhesion and spreading of MG-63 osteoblastic cells as initial cellular effect. Furthermore, it could be demonstrated that a direct correlation does not exist between the densities of primary amino groups and an enhanced cell growth. In fact, not only the primary amino groups but also other nitrogen-functional groups as e.g. acid amides or imides play a role for initial cell functions. All examined plasma polymer coatings enable the cells to literally melt into the structure of the titanium alloy substrate. The edges of the cells can hardly be distinguished from the surface.

Selective adhesion of intestinal epithelial cells on patterned films with amine functionalities formed by plasma enhanced chemical vapor deposition

Control of cell adhesion to surfaces is important to develop analytical tools in the areas of biomedical engineering. To control cell adhesiveness of the surface, we constructed a variety of plasma polymerized hexamethyldisiloxane (PPHMDSO) thin films deposited at the plasma power range of 10–100W by plasma enhanced chemical vapor deposition (PECVD). The PPHMDSO film that was formed at 10W was revealed to be resistant to cell adhesion. The resistance to cell adhesion is closely related to physicochemical properties of the film. Atomic force microscopic data show an increase in surface roughness from 0.52nm to 0.74nm with increasing plasma power. From Fourier transform infrared (FT-IR) absorption spectroscopy data, it was also determined that the methyl (–CH3) peak intensity increases with increasing plasma power, whereas the hydroxyl (–OH) peak decreases. X-ray photoelectron spectroscopy data reveal an increase in C–O bonding with increasing plasma power. These results suggest that C–O bonding and hydroxyl (–OH) and methyl (–CH3) functional groups play a critical part in cell adhesion. Furthermore, to enhance a diversity of film surface, we accumulated the patterned plasma polymerized ethylenediamine (PPEDA) thin film on the top of the PPHMDSO thin film. The PPEDA film is established to be strongly cell-adherent. This patterned two-layer film stacking method can be used to form the selectively limited cell-adhesive PPEDA spots over the adhesion-resistant surface.

Culturing of Rat Intestinal Epithelial Cells-18 on Plasma Polymerized Ethylenediamine Films Deposited by Plasma Enhanced Chemical Vapor Deposition

Many researchers studied cell culturing on surfaces with chemical functional groups. Previously, we reported surface properties of plasma polymerized ethylenediamine (PPEDA) films deposited by plasma enhanced chemical vapor deposition with various plasma conditions. Surface properties of PPEDA films can be controlled by plasma power during deposition. In this work, to analyze correlation of cell adherence/proliferation with surface property, we cultured rat intestinal epithelial cells-18 on the PPEDA films deposited with various plasma powers. It was shown that as plasma power was decreased, density of cells cultured on the PPEDA film surface was increased. Our findings indicate that plasma power changed the amine density of the PPEDA film surface, resulting in density change of cells cultured on the PPEDA film surface.

Simultaneous detection of five indices of hepatitis B based on an integrated automatic microfluidic device

Immunophenotyping evaluation is of particular importance for the clinical diagnosis, therapy, and prognosis of viral hepatitis. In this study, an integrated micro flow device has been developed to detect the differentiated antigens/antibodies for immunophenotyping of viral hepatitis. The sensors were fabricated with plasma-polymerized ethylenediamine film (PPF) and nanometer-sized gold particles (nanogold) on which the different hepatitis B antigens/antibodies (markers) were subsequently immobilized. Monitoring the changes in the potential signals before and after the antigen-antibody interaction provides the basis for an immunoassay that is simple, rapid, and cost-effective. It permits the detection of hepatitis B in the dynamic concentration range of 2 orders of magnitude (10(-6) g x L(-1) - 10(-4) g x L(-1)). Up to 7 successive assay cycles with retentive sensitivity were achieved for the sensors regenerated by 8 M urea. Moreover, the microfluidic device was applied to evaluate a number of practical specimens with analytical results in acceptable agreement with those clinically classified. The newly proposed multiparameter analysis technique provides a feasible alternative tool for the diagnosis and monitoring of hepatitis B.

Quantitative analysis of surface amine groups on plasma-polymerized ethylenediamine films using UV–visible spectroscopy compared to chemical derivatization with FT-IR spectroscopy, XPS and TOF-SIMS

A quantitative analysis of the surface density of amine groups on a plasma-polymerized ethylenediamine thin film deposited on a platinum surface using inductively coupled plasma chemical vapor deposition method is described. UV–visible spectroscopy together with a chemical derivatization technique using Fourier transform infrared (FT-IR) spectroscopy was used to obtain the quantitative information. Chemical tags of pentafluorobenzaldehyde were hybridized with the surface amine groups and were easily detected due to the characteristic absorption bands of C–F stretching, aromatic ring and C N stretching vibrations in the reflection–absorption FT-IR spectra. The surface amine density was reproducibly controlled as a function of deposition plasma power and quantified using UV–visible spectroscopy. A good linear correlation was observed between the FT-IR intensities of the characteristic absorption bands and the surface amine densities, suggesting the possibility of using this chemical derivatization technique to quantify the surface densities of specific functional groups on an organic surface. Chemical derivatization was also used with X-ray photoelectron spectroscopy on the same samples, and the results were compared with those obtained from FT-IR and time-of-flight secondary ion mass spectrometry. Although each analysis technique has different probing depths from the surface, the three different data sets obtained from the chemical tags correlated well with each other since each analysis technique measured the chemical tags on the sample surface.

Chemical derivatization technique in ToF-SIMS for quantification analysis of surface amine groups

A chemical derivatization technique in ToF-SIMS along with principal component analysis (PCA) were used to perform a quantitative study of the surface amine density of the plasma-polymerized ethylenediamine (PPEDA) thin film. We used the scores on principal component (PC) 1 from a PCA of ToF-SIMS data for the PPEDA films and their chemical-derivatized surfaces for comparison with the surface amine densities. These surface amine densities were independently determined by UV–visible spectroscopy. Our work found a good linear relationship between the surface amine densities and the scores on PC 1 from a PCA of the ToF-SIMS data for the chemical-derivatized PPEDA surfaces, but not for the PPEDA thin films themselves. In addition to quantification, our PCA results provided insights into the surface chemical composition of each surface.

Formation of amine groups by plasma enhanced chemical vapor deposition and its application to DNA array technology

A plasma enhanced chemical vapor deposition (PECVD) method using plasma polymerized ethylenediamine (PPEDA) was employed to coat glass slides with amine functional groups. Fluorescein isothiocyanate (FITC) labeling indicated that the density of amine functional groups on these coated slides was affected by PECVD conditions, particularly deposition time. The PPEDA-coated slides were used for the development of DNA arrays. 5′-Amino-modified oligodeoxyribonucleotides (ODNs) and cDNA strands were immobilized onto PPEDA-coated slides and used for hybridization to labeled target strands. In addition, patterning of amine groups, which is a very useful technique for preparing high-density DNA arrays, was achieved by selectively depositing PPEDA films on specific areas of a glass surface. These results demonstrate that the formation of amine groups on glass slides by PECVD is an excellent tool for DNA array technology.

Quantitative Chemical Derivatization Technique in Time-of-Flight Secondary Ion Mass Spectrometry for Surface Amine Groups on Plasma-Polymerized Ethylenediamine Film

A chemical derivatization technique in time-of-flight secondary ion mass spectrometry (TOF-SIMS) has been developed to quantify the surface density of amine groups of plasma-polymerized ethylenediamine thin film deposited on a glass surface by inductively coupled plasma chemical vapor deposition. Chemical tags of 4-nitrobenzaldehyde or pentafluorobenzaldehyde were hybridized with the surface amine groups and were detected in TOF-SIMS spectra as characteristic molecular secondary ions. The surface amine density was controlled in a reproducible manner as a function of deposition plasma power and was also quantified using UV-visible spectroscopy. A good linear correlation was observed between the results of TOF-SIMS and UV-visible measurements as a function of plasma power. This shows that the chemical derivatization technique in TOF-SIMS analysis would be useful in quantifying the surface density of specific functional groups that exist on the organic surface.

A potentiometric acetylcholinesterase biosensor based on plasma-polymerized film

A potentiometric acetylcholinesterase biosensor based on pH-sensitive PVC membrane with plasma-polymerized ethylenediamine film has been proposed. Glow discharge plasma technique was utilized to deposit a film containing amino groups on the surface of pH-sensitive PVC membrane. Such an approach makes it possible to fabricate a very simple self-mounted acetylcholinesterase membrane directly attached to PVC pH-sensing electrode surface. The deposition conditions were optimized and the optimum plasma polymerization parameters were as follows: applied power, 75 W; pressure, 130 Pa; plasma exposure time, 60 min and flow rates, 10 ml min −1. Two neutral carriers, DOODA and DAMAB were compared as the pH-carrier, and the biosensor based on DAMAB showed better response characteristics. The effect of pH of the medium was also examined. The potential responses of biosensor increase with the acetylcholine chloride concentration over the concentration range of 10 −6 to 10 −1 mol dm −3 and the detection limit is 0.002 mmol dm −3 in pH 8.0 PB buffer solution. The biosensor was employed more than 200 times in 20 days while the maximum response span of biosensor retained 90%.

A plasma-polymerized film for capacitance immunosensing

A capacitance immunosensor based on a plasma-polymerized ethylenediamine film (PPEF) has been developed. The resulting PPEF is studied with scanning electrode micrograph (SEM), IR reflection spectrum and cyclic voltammetry. SEM and IR reflection spectrum showed that the plasma-polymerized film (PPF) formed on the gold electrode surface is quite homogeneous, flat, nonporous and contains plenty of free-reacted NH 2. Moreover, cyclic voltammetry showed that the hexacyanoferrate redox reactions were blocked well by the formed PPF, that is to say, the formed PPF has excellent insulating characteristics. To investigate its applicability for capacitive immunosensing, goat-anti-human IgG antibody (IgGAb) was coupled to the PPF-coated gold electrode surface via glutaraldehyde (GA) to form an immunoglobulin G (IgG) probe. Alternating current (ac) impedance and capacitance measurement were used in the immunoassay. The experiment results show that the PPEF is applicable to form insulating layer of capacitive immunosensors.

Protein immobilization on plasma-polymerized ethylenediamine-coated glass slides

For protein chip construction, protein immobilization on the surface of the glass slide is essential. It was previously reported that glass slides are embedded with chemicals that contain primary amines and aldehydes for protein immobilization. We fabricated a plasma-polymerized ethylenediamine (PPEDA)-coated slide that exposed primary amines. For the plasma polymer deposition on the glass slide, the inductively coupled plasma (ICP) power was found to be a critical factor in sustaining a high density of amine on the surface of the PPEDA films. We prepared PPEDA-coated slides at three different ICP powers (3, 30, or 70 W). In the slide that was prepared at a low ICP power (3 W), we detected a high density of primary amine. Therefore, the fluorescein isothiocyanate-conjugated immunoglobulin G (IgG) was highly immobilized to the PPEDA-coated slide that was prepared at the low ICP power. For protein immobilization, 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC) was used as a cross-linker. The immobilization of the protein to the PPEDA-coated slide was carried out by consecutive incubations with 1 mg/ml EDC for 5 min and 0.1 mg/ml IgG for 1 h. This efficiently produced the functionally active protein-immobilized slide. Therefore, this work shows that the plasma technique can be applied to produce a high-quality glass surface for the immobilization of proteins and other materials.

Detection of the red tide-causing planktonAlexandrium affineby a piezoelectric immunosensor using a novel method of immobilizing antibodies

In this paper, the determination of Alexandrium affine in sea water was performed using piezoelectric immunosensors. In addition, we report a novel method of immobilizing antibodies on the quartz crystal immunosensors using plasma-polymerized ethylenediamine film. The films formed on the quartz crystals are extremely thin, homogeneous and incorporate amino groups. Sensors produced using this method show higher sensitivity than sensors made using conventional immobilization methods for example polyethylenimine or γ-aminopropyltrimethoxysilane.