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It has been demonstrated that surfaces coated with poly(ethylene glycol) (PEG) are capable of reducing protein adsorption, bacterial attachment, and biofilm formation. In this communication cold-plasma–enhanced processes were employed for the deposition of PEG-like structures onto stainless steel surfaces. Stainless steel samples were coated under 1,4,7,10-tetraoxacyclododecane (12-crown-4)–ether and tri(ethylene glycol) dimethyl ether (triglyme)–radio frequency (RF)–plasma conditions. The chemistry and characteristics of plasma-coated samples and biofilms were investigated using electron spectroscopy for chemical analysis (ESCA), atomic force microscopy (AFM), and water contact angle analysis. ESCA analysis indicated that the plasma modification resulted in the deposition of PEG-like structures, built up mainly of –CH2CH2O– linkages. Plasma-coated stainless steel surfaces were more hydrophilic and had lower surface roughness values compared to those of unmodified substrates. Compared to the unmodified surfaces, they not only significantly reduced bacterial attachment and biofilm formation in the presence of a mixed culture of Salmonella typhimurium,Staphylococcus epidermidis, and Pseudomonas fluorescens but also influenced the chemical characteristics of the biofilm. Thus, plasma deposition of PEG-like structures will be of use to the food-processing and medical industries searching for new technologies to reduce bacterial contamination. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3425–3438, 2001

Polyester (PET) swatches are treated with an electrical discharge plasma of a reactive atmosphere (tetrachlorosilane) to graft chlorosilane groups, subsequently hydrolyzed to very hydrophilic hydroxysilane groups. The Kawabata evaluation system for fabrics (KES-FB), high resolution microscopy, and surface tension measurements are used to investigate the physical properties of the fabrics before and after plasma exposure. The results show that the surface parameters are considerably modified by the treatment.

It is known that for creating advanced polyolefin/cement-based composites the polymer surface should be converted into a layer which is compatible with the inorganic component. In this respect, plasma chemistry offers additional solutions to the wet chemistry approach. It has been demonstrated during the last decade that cold plasma-mediated reactions are suitable for etching and surface functionalizing even the most inert polymeric substrates, including Teflon, polypropylene (PP), and polyethylene (PE). In this paper composite preparations from SiCl4-cold plasma and chromic acid-treated fibrillated PP substrates and cement are described. The nature of plasma- and wet chemistry-induced surface functionalization and etching processes was monitored using survey and high-resolution X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, atomic force microscopy (AFM), and dynamic water contact angle measurements. It has been demonstrated that th...

Summary A novel plasma-enhanced coating for wood substrates has been developed which diminishes the degradation of wood under simulated harsh environmental conditions. Reflective (zinc oxide) and electromagnetic radiation (EMR)-absorbent (benzotriazole, 2-hydroxybenzophenone, phtalocyanine, and graphite) substances were incorporated into a liquid phase, high-molecular-weight polydimethylsiloxane and deposited as thin layers on wood surfaces. The macromolecular films, containing the dispersed materials, were then converted into a three-dimensional solid state network by exposure to a 30 kHz-oxygen-RF-plasma. The discharge induced chemistry and altered surface topographies in the surface layers were monitored by survey and high resolution Electron Spectroscopy for Chemical Analysis, Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy, and Scanning Electron Microscopy. The surface characteristics and the resistance to weathering of the plasma treated substrates were evaluated and compared to the properties of un-modified samples.

To improve the overall performance of wood-plastic composites, appropriate technologies are needed to control moisture sorption and to improve the interaction of wood fiber with selected hydrophobic matrices. The objective of this study was to determine the surface thermodynamic characteristics of a wood fiber and to correlate those characteristics with the fiber's water vapor adsorption behavior. The surface thermodynamic properties, determined by inverse gas chromatography at infinite dilution or near zero surface coverage, were the dispersive component of the surface energy, surface acid-base free energy and enthalpy of desorption of acid-base probes, and surface acid-base acceptor and donor parameters (K A and K D ). Water vapor adsorption was expressed in terms of the percentage of weight gain (ΔW%) resulting from water vapor adsorption on the wood particles, calculated relative to their initial weight after preconditioning in a vacuum dessicator at room temperature. The results showed a strong correlation between ΔW% and K A , and between ΔW% and surface acid-base free energy of water desorption (ΔH AB water ), calculated from experimental K A and K D and values in the literature for acceptor and donor values of water. These results suggest that for substrates such as wood, whose surface Lewis acid-base properties are characterized by a relatively stronger tendency to accept electrons, the key to controlling water vapor adsorption is to manipulate the magnitude of ΔH AB water , primarily via K A , and to a lesser extent via K D .

Summary Southern yellow pine wood surfaces were modified under cold plasma conditions in order to create water repellent characteristics. The surface chemistry of the plasma “polymerized” hexamethyldisiloxane (PHMDSO) deposited onto wood surfaces was investigated using Electron Spectroscopy for Chemical Analysis (ESCA) and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR). The presence of a crosslinked macromolecular structure, based on Si-O-Si and Si-O-C linkages was detected. Pyrolysis Mass Spectroscopy (MS) was carried out to investigate the nature of the building blocks of the plasma generated macromolecular structure. Plasma modified samples exhibited very high water contact angle values (contact angle = 130 degrees) in comparison to the unmodified samples (contact angle ≤ 15 degrees), indicating the presence of a hydrophobic surface. Atomic Force Microscopy (AFM) images, collected both from unmodified and HMDSO-plasma modified samples, indicate the progressive growth of the plasma “polymer”, resulting in the deposition of a smooth layer at 10 minutes treatment time. Differential Thermal Analysis (DTA) indicated high thermal stability of the PHMDSO.

Isobutylene was polymerized by Si2Cl6-RF-plasma-generated silylium ions. Initiation is due to Cl x Si+ in-situ adsorbed on frozen isobutylene surfaces at liquid nitrogen temperature. The polymerization of isobutylene occurs in the absence of counterions. According to survey and high resolution ESCA spectra, silicon is present in the resulting polymers, which suggests initiation by Cl x Si*. FT-IR, 1H- and 13C-NMR spectroscopies, GC-MS, high resolution pyrolysis MS, as well as FAB and FI-MS analyses indicate that plasma-polymerized isobutylenes are linear oligomers of broad molecular weight distribution. DTA-TG analyses substantiate the conclusion that the average molecular weight of plasma-polymerized isobutylene is low. The findings demonstrate the usefulness of RF-plasma for generating silylium ions and silylium ions-mediated cationic polymerization. The possibility of producing novel polyisobutylene/polysiloxane block copolymers is suggested.

A non-myeloablative conditioning protocol containing dibromomannitol (DBM/cytosine arabinoside/cyclophosphamide) has been applied to 36 chronic myeloid leukemia (CML) patients followed by bone marrow transplantation (BMT) from sibling donors. Risk factors include: accelerated phase (10 patients), older age (17 patients over >40 years) and long interval between diagnosis and BMT (27 months on average). Severe mucositis did not occur. Venoocclusive liver disease was absent. Infectious complications were rare. Although grade II–IV acute graft-versus-host disease (GVHD) was present in 9 (25%) cases, there were only 2 serious (III–IV) ones. Chronic GVHD occurred in 25 (69%) cases, preceded by acute GVHD in 9 of the 25 affected patients. Early hematological relapse, 7–29 weeks after BMT, developed in 6 patients (17.6%). No relapse was noted in the completely chimeric patients, however molecular genetic residual disease was observed in 6 patients, in most of them after transient short-term mixed chimeric state. Overall actual survival rate is 83.3% for the 36 cases, and leukemia-free survival is 72.2% for the 34 engrafted patients.

Because of the increased risk of infection with the associated diagnostic and therapeutic problems in bone marrow transplantation (BMT) patients, the usefulness of surveillance cultures (SC) at the BMT department of the National Institute of Haematology, Blood Transfusion, Transplantation and Immunology, Budapest, was reviewed. Between January 1992 and May 1995, 26 BMT operations were performed; 13 patients had 23 febrile espisodes. In 12 of these episodes infection was clinically documented; however, SC of these patients yielded bacteria identical with those in the blood culture in only two episodes (1 and 6 days before their blood cultures became positive, respectively). Out of a total of 1187 samples from these patients, potentially pathogenic bacteria were isolated from 145 SC and 43 blood cultures (drawn on 31 different days). Suppression of the gastrointestinal flora could be achieved by the department's decontamination regimen; however, overgrowth by gram-positive organisms (mainly coagulase-negative staphylococci) occurred in the intestine and at other body sites. On the basis of these results, SC are of limited value in predicting infection or identifying the causative organisms of fever. On the other hand, SC are useful in confirming the efficiency of suppression of the body flora by antimicrobial agents. Specific treatment was based on suitably sampled materials, and close contact between physicians, infectious disease specialists and microbiologists was essential.

Conditioning regimens for BMT are important in determining transplant outcome. A radiation-free protocol containing Mitobronitol (DBM), Cytarabine (Ara-C) and Cyclophosphamide (Cy) was used for conditioning of patients with chronic granulocytic leukemia (CGL). Using this conditioning treatment, fewer transplant related complications, including acute GVHD, VOD and severe infections, were observed. Acute GVHD did not develop, but chronic GVHD, accompanied with graft-versus leukemia, was present in half of the cases. To determine the clinical effect of the DBM/Ara-C/Cy conditioning, the recovery of peripheral blood lymphocytes was examined after allogeneic BMT for patients with CGL in comparison with TBI/Cy conditioning. The lymphocyte subsets of 11 DBM patients were followed and analyzed periodically (30-90 days, 4-12 months and > 13 months) using ten monoclonal antibodies and flow cytometry. Decreased percentage of total T cells as well as CD4+ and CD8+ subpopulations, significantly decreased T cell activation and increased proportion of TCR gamma delta + cells were found to be characteristic in the early post-transplant period in the DBM group. Early recovery and consistently higher percentage of B cells were observed for the whole follow-up period of patients receiving DBM conditioning. A high proportion of NK cells was observed in all transplant recipients. These findings suggest that the characteristic pattern of recovering lymphocytes is associated with the lack of severe transplant-related clinical complications following DBM/Ara-C/Cy conditioning.

Our approach serves several purposes: To demonstrate the response of aortic cell nuclei to a changing environment (e.g. hypercholesterolemia, experimental diabetes, drug treatment), to apply the acridine orange (AO) ultracytochemical method, and to determine the euchromatin/heterochromatin (EU/HET) ratio by morphometric procedures as suitable criteria, and to emphasize the differential nuclear activity of adventitial cells. Hypercholesterolemia in rabbits results in an increase of AO positive nuclei in the adventitia. Additional treatment with tinofedrine, a new cerebral vasodilator drug, reveals an even higher number of AO positive nuclei in adventitial and also in endothelial and plaque cells. In streptozotocin induced diabetes in rats the increased number of AO positive cells coincides with an elevated EU/HET ratio.