Polyethylene Glycol Film Research Articles

The effect of sterilization processes on the bioadhesive properties and surface chemistry of a plasma-polymerized polyethylene glycol film: XPS characterization and L929 cell proliferation tests

The influence of several sterilization processes (autoclaving, γ-ray irradiation, ethylene oxide exposure and Ar/H 2 low pressure plasma treatment) on the surface chemistry and the bioadhesive properties of thin films (thickness ∼20 nm) of plasma-polymerized diethylene glycol dimethyl ether has been studied. X-ray photoelectron spectroscopy (XPS) analysis and cell proliferation tests were used to characterize the surfaces. The XPS results revealed in all cases a change in the surface chemistry of the layer after sterilization, whereas the conservation of non-bioadhesive properties of the coating depends on the type of sterilization process. In particular, the low pressure plasma-based sterilization technique leads to a loss of the non-bioadhesive properties of the plasma coating, whereas the coatings are resistant to the other standard decontamination techniques. This property makes them suitable for biomedical applications, provided that an appropriate sterilization process is selected.

Use of polyethylene glycol coatings for optical fibre humidity sensing

Humidity induced change in the refractive index and thickness of the polyethylene glycol (PEG) coatings are in situ investigated for a range from 10 to 95%, using an optical waveguide spectroscopic technique. It is experimentally demonstrated that, upon humidity change, the optical and swelling characteristics of the PEG coatings can be employed to build a plastic fibre optic humidity sensor. The sensing mechanism is based on the humidity induced change in the refractive index of the PEG film, which is directly coated onto a polished segment of a plastic optical fibre with dip-coating method. It is observed that PEG, which is a highly hydrophilic material, shows no monotonic linear response to humidity but gives different characteristics for various ranges of humidity levels both in index of refraction and in thickness. It undergoes a physical phase change from a semi-crystalline structure to a gel one at around 80% relative humidity. At this phase change point, a drastic decrease occurs in the index of refraction as well as a drastic increase in the swelling of the PEG film. In addition, PEG coatings are hydrogenated in a vacuum chamber. It is observed that the hydrogen has a preventing effect on the humidity induced phase change in PEG coatings. Finally, the possibility of using PEG coatings in construction of a real plastic fibre optic humidity sensor is discussed.

Characteristic of hyaluronic acid derivative films cross-linked by polyethylene glycol of low water content

Objective To test the characteristics of hyaluronic acid (HA) derivative cross-linked by polyethylene glycol films of low water content. Methods The cross-linked HA film with 200 μm thickness was got at atmospheric pressure at 25°C for 5 d. After dried, cross-linked films of 10 mm × 10 mm were weighed and immersed in phosphate buffered saline (PBS pH 7.45) at 37°C for 24 h. Then the solution fraction and water content were estimated. Meanwhile, cross-linked HA derivative films were immersed in phosphate buffered saline (PBS: pH 7.45) at 37°C for determined time and then implanted subcutaneously in the back of white rats to test in vitro or in vivo degradation characteristic. Results and Conclusion HA hydrogel cross-linked by polyethylene glycol with water content is as low as 60% and this kind of HA derivative has a slow degradation rate.

Impedance Spectroscopy Study of Composite Thin Films of Hydrated Polyethylene Glycol

A polyethylene glycol (PEG) polymer was synthesized using a dip-coating procedure on 316L stainless-steel (SS) substrate precoated with a primer that consisted of radio-frequency inductively coupled plasma-polymerized di (ethylene glycol) vinyl ether (EO2V). The primer and PEG composite film was studied with profilometer, optical microscope, scanning electron microscope (SEM), and a tape test to evaluate thickness, coverage, morphology, and adhesion, respectively. Response of the PEG composite film to an applied ac voltage was studied as a function of hydration state using impedance spectroscopy (IS). A resistor/capacitor network was used to interpret the impedance spectra. Electrical capacitance of the PEG film decreased with an exponentially decaying term as dehydration progressed. PEG-film capacitance decay was consistent with a model describing water molecules diffusing through the PEG film.

In situ measurement of humidity induced changes in the refractive index and thickness of polyethylene glycol thin films

Humidity induced changes in the refractive index and thickness of polyethylene glycol (PEG) thin films are in situ determined by optical waveguide spectroscopy. PEG brushes are covalently attached to the surface of a thin gold film on a borosilicate crown glass using a grafting-from chemical synthesis technique. The measurements are carried out in an attenuated total internal reflection setup. At low humidity levels, both the refractive index and the thickness change gradually due to swelling of the PEG thin films upon water intake. At around 80% relative humidity, a steep decrease in the refractive index and a steep increase in the thickness are observed as a result of a phase change from a semicrystalline state to a physical gel state. The hydrogenation of PEG films causes a less pronounced phase change from a semicrystalline state to a gel state. Due to fewer ether oxygen atoms available for the water molecules to make hydrogen bonding, the polymer has a more stable structure than before and the phase change is observed to shift to higher humidity levels. It is discussed that such a humidity induced change in the index of refraction can be utilized in constructing a PEG based humidity sensor.

Water ice as a matrix for film production by matrix-assisted pulsed laser evaporation (MAPLE)

We have studied water ice as a matrix for the production of PEG (polyethylene glycol) films by MAPLE at 355 nm. The deposition rate is small compared with other matrices typically used in MAPLE, but the deposition of photofragments from the matrix can be avoided. At temperatures above −50°C of the target holder the deposition rate increases strongly, but the evaporation pressure in the MAPLE chamber also increases drastically.

High fluence deposition of polyethylene glycol films at 1064 nm by matrix assisted pulsed laser evaporation (MAPLE)

Matrix assisted pulsed laser evaporation (MAPLE) has been applied for deposition of thin polyethylene glycol (PEG) films with infrared laser light at 1064 nm. We have irradiated frozen targets (of 1 wt.% PEG dissolved in water) and measured the deposition rate in situ with a quartz crystal microbalance. The laser fluence needed to produce PEG films turned out to be unexpectedly high with a threshold of 9 J/cm 2, and the deposition rate was much lower than that with laser light at 355 nm. Results from matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis demonstrate that the chemistry, molecular weight and polydispersity of the PEG films were identical to the starting material. Studies of the film surface with scanning electron microscopy (SEM) indicate that the Si-substrate is covered by a relatively homogenous PEG film with few bare spots.

UV/O2가스상 세정을 이용한 실리콘 웨이퍼상의 PEG 반응기구의 관찰

An experiment to find out the removal mechanism of PEG(polyethyleneglycol) by using UV-enhanced GPC (gas phase cleaning) at low substrate temperature below was executed under various process conditions, such as substrate temperature, UV exposure, and gas. The possibility of using GPC as a low-temperature in-situ cleaning tool for organic removal was confirmed by the removal of a PEG film with a thickness of about 200 nm within 150 sec at a substrate temperature of . Synergistic effects by combining photo-dissociation and photo oxidation can only remove the entire PEG film without residues within experimental splits. In GPC with substrate temperatures higher than the glass transition temperature, the substantial increase in the PEG removal rate can be explained by surface-wave formation. The photo-dissociation of PEG film by UV exposure results in the formation of end aldehyde by dissociation of back-bone chain and direct decomposition of light molecules. The role of oxygen is forming peroxide radicals and/or terminating the dis-proportionation reaction by forming peroxide.

Dispersion of Barium Ferrite Particles for Slip Casting in Magnetic Field

Water-based slurries containing barium ferrite particles have been prepared and slip cast in magnetic field. This paper presents the characteristics of the suspensions in terms of Iso-Electric Points (IEP) and zeta potential that were evaluated through pH titration and polymer adsorption. Both enlarging the specific surface area of particles by planetary milling and adjusting the pH to low value apparently increase the zeta potentials. Stable slurry was obtained by adding polyethylene glycol (PEG) into the suspension at pH = 2 ~ 3.5. The steric repulsion plays key role in dispersion and PEG films served as insulative layers and mechanically kept particles from contact each other. The barium ferrite particles formed many stacks of plates during slip casting, which either aligned randomly without magnetic field applied or regularly aligned to form textured structure when magnetic field was applied.

Polyethylene Glycol Deposition Techniques for Antifouling Surfaces: Using Antistiction to Conserve Bioparticles for Recovery and Analysis

ABSTRACTFor bioparticle analysis within microfluidic devices, there is a risk of analytes adhering to surfaces, thereby compromising particle manipulation and recovery. To address this we have implemented polyethylene glycol (PEG)-type coatings by self-assembled monolayer (SAM) and plasma-polymerizing deposition techniques. Silane chemistry is used to deposit SAM films directly onto silicon dioxide surfaces, and in a special case for which a composite of metallic arrays and SiON within our MEMS device must be coated, an ultrathin layer of sputtered Si is added before the SAM protocol. We have also deposited PEG-like tetraglyme by plasma-polymerization onto substrates using an onsite-built reactor to provide antistiction treatment to all surfaces, including those that do not have chemical compatibility for the SAM technique. Three tests demonstrate the effectiveness of our surface treatments: static exposure to microbial suspensions, bioparticle transport across MEMS traveling-wave (TW) arrays, and bioparticle recovery from a circulating flow device. Our static microbial assays show significant reduction in B. thuringiensis adhesion to both the SAM and plasma-polymerized coatings and reduction in B. globigii adhesion to the plasma-polymerized coating. Our TW arrays, when coated with either the SAM or plasma-polymerized PEG film, are effective at reducing adhesion to polystyrene beads as well as both Bacillus species. Lastly, our bioparticle recovery, as gauged by spectrophotometry, improves by as much as one order of magnitude when we coat flow chambers with our plasma-polymerized film.

Surface morphology of polyethylene glycol films produced by matrix-assisted pulsed laser evaporation (MAPLE): Dependence on substrate temperature

Abstract The dependence of the surface morphology on the substrate temperature during film deposition was investigated for polyethylene glycol (PEG) films by matrix-assisted pulsed laser evaporation (MAPLE). The surface structure was studied with a combined technique of optical imaging and AFM measurements. There was a clear difference between the films produced below and above the melting point of PEG. For temperatures above the melting point, the polymer material was distributed non-uniformly over the substrate with growths areas, where cluster-like structures merge into large islands of micrometer size. At these temperatures, the islands in the investigated growth areas cover most of the bottom layer which has a typical height of 50–150 nm.

Direct Electrochemistry and Catalytic Activity of Hemoglobin and Myoglobin Entrapped in PEG Film

Direct electrochemistry and electrocatalysis of two heme proteins, hemoglobin (Hb) and myoglobin (Mb), incorporated in polyethylene glycol (PEG) films, were studied by cyclic voltammetry. The two proteins exhibited a pair of well‐defined, quasi‐reversible cyclic voltammetric peaks with the apparent formal potential at about −0.21 V (Hb) and −0.22 V (Mb), respectively, vs. saturated calomel electrode (SCE) in pH 5.0 acetate buffer solution, characteristic of the h eme Fe(III)/Fe(II) redox couples, indicating enhanced electron transfer between the proteins and the substrate electrode in the PEG film environment. The protein–PEG films could also exhibit excellent stability. Meanwhile, positions of Soret absorption band of the proteins in the PEG films suggested that the heme proteins kept their secondary structure similar to their native state in the medium pH range. Oxygen, trichloroacetic acid, nitric oxide, and hydrogen peroxide could all be catalytically reduced by Hb or Mb in PEG films.

Effects of Antidepressant Medication on Morbidity and Mortality in Depressed Patients After Myocardial Infarction

Polyethylene glycol (PEG) brushes are very effective at controlling non-specific deposition of biological material onto surfaces, which is of paramount importance to obtaining successful outcomes in biomaterials, tissue engineered scaffolds, biosensors, filtration membranes and drug delivery devices. We report on a simple ‘grafting to’ approach involving binary solvent mixtures that are chosen based on Hansen's solubility parameters to optimize the solubility of PEG thereby enabling control over the graft density. The PEG thiol-gold model system enabled a thorough characterization of PEG films formed, while studies on a PEG silane-silicon system examined the versatility to be applied to any substrate-head group system by choosing an appropriate solvent pair. The ability of PEG films to resist non-specific adsorption of proteins was quantitatively assessed by full serum exposure studies and the binary solvent strategy was found to produce PEG films with optimal graft density to efficiently resist protein adsorption.

Fabrication of nanostructures of polyethylene glycol for applications to protein adsorptionand cell adhesion

A simple method was developed to fabricate polyethylene glycol (PEG)nanostructures using capillary lithography mediated by ultraviolet (UV) exposure.Acrylate-containing PEG monomers, such as PEG dimethacrylate (PEG-DMA,MW = 330), were photo-cross-linked under UV exposure to generate patterned structures. Incomparison to unpatterned PEG films, hydrophobicity of PEG nanostructuremodified surfaces was significantly enhanced. This could be attributed to trappedair in the nanostructures as supported by water contact angle measurements.Proteins (fibronectin, immunoglobulin, and albumin) and cells (fibroblasts andP19 EC cells) were examined on the modified surfaces to test for the level ofprotein adsorption and cell adhesion. It was found that proteins and cells preferredto adhere on nanostructured PEG surfaces in comparison to unpatterned PEGfilms; however, this level of adhesion was significantly lower than that of glasscontrols. These results suggest that capillary lithography can be used to fabricatePEG nanostructures capable of modifying protein and cell adhesive properties ofsurfaces.

Study of microcapillary pipette-assisted method to prepare polyethylene glycol-coated microcantilever sensors

Microcantilever sensors were prepared by direct deposition of polyethylene glycol (PEG) onto the microcantilever surfaces using a microcapillary pipette. The physical properties of the PEG coatings: mass, surface area, volume and thickness were studied. The sensors were tested by exposing them to trace ethanol vapor and the physical properties of the micropipette-deposited PEG coatings were correlated with sensor response. Most of the PEG-coated microcantilevers demonstrated reproducible bending signals upon repeated exposure to ethanol (EtOH) vapor. Evident in the study is that uniformity in the gross morphology and surface structure of the PEG coating was not required for good sensor response. However, the location of the PEG on the microcantilever, PEG film thickness and surface area contributed to optimum response to exposure to EtOH vapor. The results demonstrate the utility of direct application of coatings onto microcantilevers by the micropipette technique. This method of coating microcantilevers is particularly appealing when quick, repeated tests of coated microcantilever sensors are desired as an alternative to more complex and time-consuming coating techniques.

Tissue anti-adhesion potential of ibuprofen-loaded PLLA–PEG diblock copolymer films

This study was designed to evaluate the effect of polyethylene glycol (PEG) and nonsteroidal anti-inflammatory drug (ibuprofen) on the prevention of postsurgical tissue adhesion. For this, poly( l-lactic acid) (PLLA)–PEG diblock copolymers were synthesized by ring opening polymerization of l-lactide and methoxy polyethylene glycol (Mw 5000) of different compositions. The synthesized copolymers were characterized by gel permeation chromatography and 1H-nuclear magnetic resonance spectroscopy. PLLA–PEG copolymer films were prepared by solvent casting. The prepared copolymer films were more flexible and hydrophilic than the control PLLA film, as investigated by the measurements of glass transition temperature, water absorption content, and water contact angle. The drug release behavior from the ibuprofen (10 wt%)-loaded copolymer films was examined by high performance liquid chromatography. It was observed that the drug was released gradually up to about 40% of total loading amount after 20 days, depending on PEG composition; more drug release from the films with higher PEG compositions. In vitro cell adhesions on the copolymer films with/without drug were compared by the culture of NIH/3T3 mouse embryo fibroblasts on the surfaces. For in vivo evaluation of tissue anti-adhesion potential, the copolymer films with/without drug were implanted between the cecum and peritoneal wall defects of rats and their tissue adhesion extents were compared. It was observed that the ibuprofen-containing PLLA–PEG films with high PEG composition (particularly PLLA 113–PEG 113 film with PEG composition, 50 mol%) were very effective in preventing cell or tissue adhesion on the film surfaces, probably owing to the synergistic effects of highly mobile, hydrophilic PEG and anti-inflammatory drug, ibuprofen.

A new film for the fabrication of an unmediated H 2O 2 biosensor

A novel and stable film made from polyethylene glycol (PEG) on pyrolytic graphite (PG) electrode was presented in this paper for incorporating horseradish peroxidase (HRP) to study the direct electrochemistry of the enzyme. In PEG film, HRP showed a thin-layer electrochemistry behavior. The apparent standard potential ( E°′) was −0.379 V versus SCE at pH 7.2. Moreover, the PEG–HRP modified electrode exhibited excellent electrocatalytical response to the reduction of H 2O 2 with a calibration range between 2.0×10 −6 and 6.0×10 −4 M and a good linear relation from 2.0×10 −6 to 1.0×10 −4 M, on which an unmediated H 2O 2 biosensor was based. The detection limit of 6.7×10 −7 M was estimated when the signal-to-noise ratio was 3. The relative standard deviation (R.S.D.) was 4.7% for six successive determinations at a concentration of 4.0×10 −5 M. The apparent Michaelis–Menten constant ( K m app) of the sensor was found to be 1.38 mM. Epinephrine, dopamine, and ascorbic acid did not interfere with the sensitive determination of H 2O 2.

The effect of the matrix on film properties in matrix-assisted pulsed laser evaporation

Thin films of polyethylene glycol of average molecular weight 1400 amu have been deposited by matrix-assisted pulsed laser evaporation (MAPLE). The deposition was carried out in vacuum (∼10−6 Torr) with an ArF (λ=193 nm) laser at a fluence of 220–230 mJ/cm2. Films were deposited on NaCl plates and glass microscope slides. Both deionized water (H2O) and chloroform (CHCl3) were used as matrices. The physiochemical properties of the films are compared via Fourier transform infrared spectroscopy, and electrospray ionization mass spectrometry. The results show that the matrix used during MAPLE can greatly affect the chemical structure and molecular weight distribution of the deposited film. The infrared absorption spectrum shows evidence for C–Cl bond formation when CHCl3 is used as a matrix, while there is little evidence in the IR data for photochemical modification when H2O is used as a matrix. Time-of-flight analysis was performed using a quadrupole mass spectrometer to monitor evaporation of a frozen CHCl3 target during laser exposure. Using this approach, we determined that the TOF spectra for m/z=35 (Cl) and m/z=85 (CHCl2) differed significantly in both width and peak arrival time, indicating that neutral chlorine atoms were produced at the target surface. We attribute the reduction in molecular weight and structural modification of the film deposited using CHCl3 to the presence of these highly reactive species.

Resonant infrared pulsed-laser deposition of polymer films using a free-electron laser

Thin films of polyethylene glycol (MW 1500) have been prepared by pulsed-laser deposition (PLD) using both a tunable infrared (λ=2.9 μm, 3.4 μm) and an ultraviolet laser (λ=193 nm). A comparison of the physicochemical properties of the films by means of Fourier transform infrared spectroscopy, electrospray ionization mass spectrometry, and matrix-assisted laser desorption and ionization shows that when the IR laser is tuned to a resonant absorption in the polymer, the IR PLD thin films are identical to the starting material, whereas the UV PLD show significant structural modification. These results are important for several biomedical applications of organic and polymeric thin films.

Vapor deposition of intact polyethylene glycol thin films

Thin films of polyethylene glycol (PEG) of average molecular weight, 1400 amu, were deposited by both matrix-assisted pulsed laser evaporation (MAPLE) and pulsed laser deposition (PLD). The deposition was carried out in vacuum (∼10-6 Torr) with an ArF (λ=193 nm) laser at a fluence between 150 and 300 mJ/cm2. Films were deposited on NaCl plates, Si(111) wafers, and glass slides. The physiochemical properties of the films are compared via Fourier transform infrared spectroscopy (FTIR), electrospray ionization (ESI) mass spectrometry, and matrix-assisted laser desorption and ionization (MALDI) time-of-flight mass spectrometry. The results show that the MAPLE films nearly identically resemble the starting material, whereas the PLD films do not. These results are discussed within the context of biomedical applications such as drug delivery coatings and in vivo applications where there is a need for transfer of polymeric coatings of PEG without significant chemical modification.