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1.
ACS Appl Mater Interfaces ; 13(28): 32790-32798, 2021 Jul 21.
Article in English | MEDLINE | ID: mdl-34232024

ABSTRACT

Cell sheet engineering represents a new era of precise and efficient regenerative medicine, but its efficacy is limited by the elaborative preparation and the weak mechanics. Herein, a near-infrared (NIR)-triggered dynamic wrinkling biointerface was designed for rapid acquisition of practical cell sheets. The biocompatible NIR can initiate the photothermal-mechanical linkage cascade to efficiently dissolve the collagen supporting layer and release the high-quality cell sheets. The interfacial shear force generates with the dynamic wrinkling, playing an active role in accelerating the cell sheet release. High-quality and self-supporting cell sheets can be harvested within a few minutes, demonstrating a new paradigm of photothermal-mechanical manipulation. The transplantable cell sheets with outstanding physiological and mechanical performances were proven to promote wound healing in skin regeneration. This method may open a completely new front in thermal and mechanical responsive cascade to harvest cell sheets, facilitating their wide applications in regenerative medicine.


Subject(s)
Cell Culture Techniques/methods , Collagen Type I/chemistry , Fibroblasts/metabolism , Myoblasts/metabolism , Regenerative Medicine/methods , Wound Healing/physiology , Acrylic Resins/chemistry , Acrylic Resins/radiation effects , Animals , Cell Line , Dimethylpolysiloxanes/chemistry , Dimethylpolysiloxanes/radiation effects , Fibroblasts/transplantation , Heating , Infrared Rays , Mice , Myoblasts/transplantation , Nanotubes, Carbon/chemistry , Nanotubes, Carbon/radiation effects , Phase Transition , Polystyrenes/chemistry , Polystyrenes/radiation effects , Proof of Concept Study , Skin Transplantation
2.
Biomed Mater ; 11(1): 015014, 2016 Feb 19.
Article in English | MEDLINE | ID: mdl-26894472

ABSTRACT

We show that femtosecond laser irradiation of polydimethylsiloxane (PDMS) enables selective and patterned cell growth by altering the wetting properties of the surface associated with chemical and/or topographical changes. In the low pulse energy regime, the surface becomes less hydrophobic and exhibits a low water contact angle compared to the pristine material. X-ray photoelectron spectroscopy (XPS) also reveals an increased oxygen content in the irradiated regions, to which the C2C12 cells and rabbit anti-mouse protein were found to attach preferentially. In the high pulse energy regime, the laser-modified regions exhibit superhydrophobicity and were found to inhibit cell adhesion, whereas cells were found to attach to the surrounding regions due to the presence of nanoscale debris generated by the ablation process.


Subject(s)
Cell Adhesion/physiology , Dimethylpolysiloxanes/chemistry , Lasers , Molecular Imprinting/methods , Myoblasts/cytology , Myoblasts/physiology , Animals , Biocompatible Materials/chemistry , Biocompatible Materials/radiation effects , Cell Line , Dimethylpolysiloxanes/radiation effects , Materials Testing , Mice , Surface Properties/radiation effects
3.
Adv Mater ; 27(6): 1083-9, 2015 Feb 11.
Article in English | MEDLINE | ID: mdl-25537971

ABSTRACT

A process to surface pattern polydimethylsiloxane (PDMS) with ferromagnetic structures of varying sizes (micrometer to millimeter) and thicknesses (>70 µm) is developed. Their flexibility and magnetic reach are utilized to confer dynamic, additive properties to a variety of substrates, such as coverslips and Eppendorf tubes. It is found that these substrates can generate additional modes of magnetic droplet manipulation, and can tunably steer magnetic-cell organization.


Subject(s)
Alloys/chemistry , Dimethylpolysiloxanes/chemistry , Electroplating/methods , Magnets , Microfluidic Analytical Techniques/instrumentation , Alloys/radiation effects , Crystallization , Dimethylpolysiloxanes/radiation effects , Elastic Modulus , Equipment Design , Equipment Failure Analysis , Magnetic Fields , Materials Testing , Miniaturization , Particle Size
4.
Lab Chip ; 14(15): 2610-3, 2014 Aug 07.
Article in English | MEDLINE | ID: mdl-24828586

ABSTRACT

Polydimethylsiloxane is a translucent and biologically inert silicone material used in sealants, biomedical implants and microscale lab-on-a-chip devices. Furthermore, in membrane technology, polydimethylsiloxane represents a material for separation barriers as it has high permeabilities for various gases. The facile handling of two component formulations with a silicone base material, a catalyst and a small molecular weight crosslinker makes it widely applicable for soft-lithographic replication of two-dimensional device geometries, such as microfluidic chips or micro-contact stamps. Here, we develop a new technique to directly print polydimethylsiloxane in a rapid prototyping device, circumventing the need for masks or sacrificial mold production. We create a three-dimensional polydimethylsiloxane membrane for gas-liquid-contacting based on a Schwarz-P triple-periodic minimal-surface, which is inaccessible with common machining techniques. Direct 3D-printing of polydimethylsiloxane enables rapid production of novel chip geometries for a manifold of lab-on-a-chip applications.


Subject(s)
Dimethylpolysiloxanes/chemistry , Lab-On-A-Chip Devices , Membranes, Artificial , Printing, Three-Dimensional , Coloring Agents/chemistry , Dimethylpolysiloxanes/radiation effects , Elastic Modulus , Equipment Design , Furans/chemistry , Materials Testing , Microscopy, Electron, Scanning , Permeability , Phosphinic Acids/chemistry , Phosphinic Acids/radiation effects , Photochemical Processes , Photosensitizing Agents/chemistry , Photosensitizing Agents/radiation effects , Solvents/chemistry , Spectrophotometry , Surface Properties , Time Factors
5.
Opt Express ; 21(14): 17028-41, 2013 Jul 15.
Article in English | MEDLINE | ID: mdl-23938551

ABSTRACT

Possibility to form three-dimensional (3D) micro-structures in silicone elastomer (polydimethylsiloxane; PDMS) doped with different photo-initiators was systematically investigated using direct laser writing with femtosecond laser pulses at different exposure conditions. Accuracy of the 3D structuring with resolution of ~5 µm and a fabrication throughput of ~720 µm(3)/s, which is exceeding the previously reported values by ~ 300(×), was achieved. Practical recording velocities of ~ 1 mm/s were used in PDMS with isopropyl-9H-thioxanthen-9-one (ISO) and thioxanthen-9-one (THIO) photo-initiators which both have absorption at around 360 nm wavelength. The 3D laser fabrication in PDMS without any photo-initiator resulting in a fully bio-compatible material has been achieved for the first time. Rates of multi-photon absorption and avalanche for the structuring of silicone are revealed: the two-photon absorption is seeding the avalanche of a radical generation for subsequent cross-linking. Direct writing enables a maskless manufacturing of molds for soft-lithography and 3D components for microfluidics as well as scaffolds for grafts in biomedical applications.


Subject(s)
Biocompatible Materials/chemistry , Biocompatible Materials/radiation effects , Dimethylpolysiloxanes/chemistry , Dimethylpolysiloxanes/radiation effects , Lasers , Tissue Scaffolds , Equipment Design , Equipment Failure Analysis , Materials Testing , Miniaturization , Surface Properties/radiation effects
6.
Odontology ; 99(1): 68-76, 2011 Jan.
Article in English | MEDLINE | ID: mdl-21271329

ABSTRACT

Physical weathering is usually responsible for the degradation of maxillofacial prosthetic elastomers and the replacement of prostheses. The purpose of this study was to investigate the effects of outdoor weathering on the physical properties of four nonpigmented facial prosthetics after 1 year of exposure. In addition, simple mathematical models were developed to correlate the measured properties with irradiation time, including parameters with physical meaning. Three different medical-grade polydimethyl siloxanes (PDMSs) and an experimental chlorinated polyethylene (CPE) were examined in this study. The samples were exposed to solar radiation for 1 year in Athens, Greece. Mechanical tests (compression and tensile) were performed using universal-type testing machine, and hardness measurements were performed with a durometer (Shore A). Thermal tests were also performed with a differential scanning calorimeter. Simple mathematical models were developed to describe the examined properties. Changes observed in the properties of examined materials, before and after the exposure, reflected the effect of weathering. More specifically, two of the silicone prosthetics (Elastomer 42, TechSIL 25) seemed to become harder and more brittle, different from the other silicone (M511) sample and the CPE sample, which became softer and more ductile. Moreover mathematical models correlate the measured properties with irradiation time, and their constants indicate that duration of exposure seems to increase the degradation. Significant changes in the mechanical and thermal properties of the examined materials were observed as a result of outdoor weathering. The effect of weathering on samples' properties was introduced through its effect on the mathematical models' parameters.


Subject(s)
Elastomers/radiation effects , Maxillofacial Prosthesis , Sunlight , Calorimetry, Differential Scanning/instrumentation , Compressive Strength , Dental Stress Analysis , Dimethylpolysiloxanes/radiation effects , Elasticity , Hardness , Hot Temperature , Materials Testing , Models, Theoretical , Polyethylenes/radiation effects , Tensile Strength , Transition Temperature , Viscosity , Weather
7.
J Prosthodont ; 20(3): 205-8, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21077983

ABSTRACT

PURPOSE: The aim of this study was to evaluate the influence of two pigments (ceramic powder and oil paint) and one opacifier (barium sulfate) on the color stability of MDX4-4210 facial silicone submitted to accelerated aging. MATERIALS AND METHODS: Sixty specimens of silicone were fabricated and divided into six groups--colorless (G1), colorless with opacifier (G2), ceramic (G3), ceramic with opacifier (G4), oil (G5), oil with opacifier (G6). All replicas were submitted to accelerated aging for 1008 hours. The evaluations of chromatic alteration through visual analysis and reflection spectrophotometry were carried out initially and after 252, 504, and 1008 hours of aging. The results were submitted to ANOVA and Tukey's test at 5% level of significance. RESULTS: All groups exhibited chromatic alteration (ΔE > 0); however, this color alteration was not perceptible through visual analysis of the color. The pigmented groups with opacifier presented the lowest ΔE values, with a statistical difference from the other groups. For the groups without opacifier, the group pigmented with oil paint exhibited the lowest ΔE values in the different aging periods, with a statistical difference. Accelerated aging generated significant chromatic alterations in all groups after 252 hours, except for the colorless and oil groups, both with opacifier (G2 and G6). CONCLUSIONS: The opacifier protects facial silicones against color degradation, and oil paint is a stable pigment even without addition of opacifier.


Subject(s)
Biocompatible Materials/chemistry , Coloring Agents/chemistry , Dimethylpolysiloxanes/chemistry , Maxillofacial Prosthesis , Prosthesis Coloring , Silicone Elastomers/chemistry , Barium Sulfate/chemistry , Biocompatible Materials/radiation effects , Ceramics/chemistry , Color , Dimethylpolysiloxanes/radiation effects , Humans , Materials Testing , Paint , Silicone Elastomers/radiation effects , Spectrophotometry, Ultraviolet , Sunlight , Surface Properties , Time Factors , Ultraviolet Rays , Water/chemistry
8.
J Biomater Sci Polym Ed ; 22(18): 2457-73, 2011.
Article in English | MEDLINE | ID: mdl-21176391

ABSTRACT

Polydimethylsiloxane (PDMS) is an elastomer that is widely used in construction and for biological and biomedical applications. The biocompatibility of PDMS was improved by different surface treatment methods, i.e., plasma treatment or a combination of plasma treatment with UV-irradiation or redox initiator, to minimize the effects of deposition of salts and proteins. In this work we used the vinyl monomers sulfobetaine and AMPS which have good biocompatible properties.


Subject(s)
Adenosine Monophosphate/analogs & derivatives , Betaine/analogs & derivatives , Biocompatible Materials/chemistry , Dimethylpolysiloxanes/chemistry , Plasma/chemistry , Thionucleotides/chemistry , Adenosine Monophosphate/chemistry , Albumins/chemistry , Betaine/chemistry , Biocompatible Materials/radiation effects , Dimethylpolysiloxanes/radiation effects , Hydrolysis , Hydrophobic and Hydrophilic Interactions , Materials Testing , Molecular Structure , Peroxides/chemistry , Photoelectron Spectroscopy , Polymerization , Salts/chemistry , Silicones/chemistry , Spectrophotometry, Infrared , Surface Properties , Ultraviolet Rays , Wettability
9.
ACS Appl Mater Interfaces ; 2(9): 2485-8, 2010 Sep.
Article in English | MEDLINE | ID: mdl-20712336

ABSTRACT

Composite films of TiO2 and polydimethylsiloxane (PDMS) are prepared by a sol-gel method, cured with UV irradiation, and then treated in hot water to crystallize the TiO2 in the film. The presence of anatase TiO2 contributes to the photoinduced superhydrophilicity of the film under UV irradiation. Contact angle studies reveal that the TiO2-PDMS composite film recovers its original hydrophobic state. Hydrophobic-superhydrophilic patterns are successfully formed on the films. The wettability patterns can be erased by UV irradiation and thermal treatment. New wettability patterns can be reconstructed, demonstrating that the film exhibits rewritable wettability without the need for organic chemicals.


Subject(s)
Dimethylpolysiloxanes/chemistry , Dimethylpolysiloxanes/radiation effects , Membranes, Artificial , Nylons/chemistry , Nylons/radiation effects , Photochemistry/methods , Titanium/chemistry , Titanium/radiation effects , Wettability/radiation effects , Hot Temperature , Materials Testing , Surface Properties/radiation effects , Ultraviolet Rays
10.
Opt Express ; 18(11): 10947-55, 2010 May 24.
Article in English | MEDLINE | ID: mdl-20588950

ABSTRACT

A new method for direct patterning of Poly(dimethylsiloxane) (PDMS) microstructures is developed by taking advantage of photorefractive effect in a functionalized substrate. Here we show that when a x-cut Iron doped Lithium Niobate (LN) crystal is exposed to appropriate structured laser light, a charge density pattern builds-up in the crystal and a space charge field arise that is able to induce self-patterning of the PDMS liquid film deposited on its surface via the dielectrophoretic effects. Proper heating treatment allows to achieve polymeric linking process creating a solid and stable PDMS microstructures. The self-patterned structures replicate the illuminating light pattern. We show that 1D and 2D patterning of PDMS gratings can be achieved. This new soft-lithographic approach can pave the way for realizing PDMS micro-structures with high degree of flexibility that avoids the need of moulds fabrication.


Subject(s)
Dimethylpolysiloxanes/chemistry , Dimethylpolysiloxanes/radiation effects , Refractometry/methods , Light , Materials Testing , Miniaturization , Surface Properties
11.
J Dent ; 38 Suppl 2: e100-5, 2010.
Article in English | MEDLINE | ID: mdl-20472021

ABSTRACT

OBJECTIVES: This study evaluated the effects of nano-oxides on the color stability of pigmented silicone A-2186 maxillofacial prosthetic elastomers before and after artificial aging. METHODS: Each of three widely used UV-shielding nano-sized particle oxides (TiO(2), ZnO, CeO(2)), based on recent survey of the industry at 1%, 2%, 2.5% concentrations were combined with each of five intrinsic silicone pigment types (no pigments, red, yellow, blue, and a mixture of the three pigments). Silicone A-2186 without nano-oxides or pigments served as control, for a total of 46 experimental groups of elastomers. In each group of the study, all specimens were aged in an artificial aging chamber for an energy exposure of 450kJ/m(2). CIE L*a*b* values were measured by a spectrophotometer. The 50:50% perceptibility (ΔE*=1.1) and acceptability threshold (ΔE*=3.0) were used in interpretation of recorded color differences. Color differences after aging were subjected to three-way analysis of variance. Means were compared by Fisher's PLSD intervals at the 0.05 level of significance. RESULTS: Yellow pigments mixed with all three nano-oxides at all intervals increased ΔE* values significantly from 3.7 up to 8.4. When mixed pigment groups were considered, TiO(2) at 2%, and 2.5% exhibited the smallest color changes, followed by ZnO and CeO(2), respectively (p<0.001). At 1%, CeO(2) exhibited the smallest color changes, followed by TiO(2) and ZnO, respectively (p<0.001). The smallest color differences, observed for nano-oxides groups, were recorded for CeO(2) at 1%, and TiO(2) at 2% and 2.5%. When the nano-oxides were tested at all concentrations, CeO(2) groups overall had the most color changes, and TiO(2) groups had the least. All ΔE* values of the mixed pigment groups were below the 50:50% acceptability threshold (ΔE*=1.2-2.3, below 3.0) except 2% CeO(2) (ΔE*=4.2). CONCLUSION: 1% nano-CeO(2) and 2% and 2.5% nano-TiO(2) used as opacifiers for silicone A-2186 maxillofacial prostheses with mixed pigments exhibited the least color changes when subjected to artificial aging at 450kJ/m(2). Yellow silicone pigment mixed with all three nano-oxides significantly affected color stability of A-2186 silicone elastomer.


Subject(s)
Biocompatible Materials/radiation effects , Coloring Agents/radiation effects , Maxillofacial Prosthesis , Nanoparticles/radiation effects , Oxides/radiation effects , Prosthesis Coloring/methods , Biocompatible Materials/chemistry , Cerium/chemistry , Cerium/radiation effects , Color , Coloring Agents/chemistry , Dimethylpolysiloxanes/chemistry , Dimethylpolysiloxanes/radiation effects , Elastomers/chemistry , Elastomers/radiation effects , Humans , Nanoparticles/chemistry , Optical Phenomena , Oxides/chemistry , Silicones/chemistry , Silicones/radiation effects , Titanium/chemistry , Titanium/radiation effects , Ultraviolet Rays , Zinc Oxide/chemistry , Zinc Oxide/radiation effects
12.
J Mater Sci Mater Med ; 21(4): 1311-9, 2010 Apr.
Article in English | MEDLINE | ID: mdl-20091101

ABSTRACT

Poly(ether) urethane (PEtU)-polydimethylsiloxane (PDMS) based materials have been processed by a spray, phase-inversion technique to produce microfibrillar small-diameter vascular grafts; however the effect of sterilization upon these grafts is still unknown. This study investigated the effect of gamma irradiation on grafts made of PEtU-PDMS materials containing different PDMS concentrations. Sterilisation-induced changes in surface chemical structure and morphology were assessed by infrared spectroscopy, light and scanning electron microscopy. Tensile tests were used to examine changes in mechanical properties and the cytotoxicity evaluation was performed on L929 fibroblasts. The study demonstrated that physical-chemical and mechanical properties of PEtU-PDMS grafts, at each PDMS concentration, were not significantly affected by the exposure to gamma irradiation, moreover no sign of cytotoxicity was observed after sterilisation. Although in vitro experiments have been promising, further in vivo studies are necessary to evaluate the biodegradation behaviour of PEtU-PDMS graft after gamma irradiation, before any clinical application.


Subject(s)
Biomechanical Phenomena/radiation effects , Blood Vessel Prosthesis/adverse effects , Dimethylpolysiloxanes/adverse effects , Dimethylpolysiloxanes/radiation effects , Gamma Rays , Physical Phenomena , Polyurethanes/adverse effects , Polyurethanes/radiation effects , Absorbable Implants/adverse effects , Animals , Biocompatible Materials/adverse effects , Biocompatible Materials/pharmacology , Biocompatible Materials/radiation effects , Cell Adhesion/drug effects , Cells, Cultured , Dimethylpolysiloxanes/chemistry , Dimethylpolysiloxanes/pharmacology , Fibroblasts/drug effects , Fibroblasts/physiology , Gamma Rays/adverse effects , Materials Testing , Mice , Microfibrils/chemistry , Microfibrils/radiation effects , Polyurethanes/chemistry , Polyurethanes/pharmacology , Sterilization/methods , Stress, Mechanical , Surface Properties/radiation effects , Tensile Strength/radiation effects
14.
Dent Mater ; 25(12): 1493-502, 2009 Dec.
Article in English | MEDLINE | ID: mdl-19683338

ABSTRACT

OBJECTIVES: The degradation of maxillofacial prosthetic elastomers that occurs during physical weathering is usually responsible for the replacement of prostheses. In this study the mechanical behavior of 4 non-pigmented facial prosthetic elastomers, exposed to outdoor weathering for 1 year, was investigated. The hypothesis investigated was that irradiation time did not affect the properties measured. METHODS: The samples were exposed to solar radiation for 1 year in Thessaloniki (Greece). Three different types of polydimethyl siloxane (PDMS) and chlorinated polyethylene (CPE) samples were tested in this study. Mechanical tests (compressive-tensile) were performed using a universal type testing machine. Hardness tests were evaluated using a durometer tester. Simple mathematical models were developed to correlate the measured properties with irradiation time. The stress-strain data of compression and tensile tests were modeled using parameters such as maximum stress (sigma(max)), maximum strain (epsilon(max)), elasticity parameter (E), and non-linearity parameter (p), while the mathematical model used for hardness data involves initial hardness of materials (H(0)). RESULTS: Two of the silicone prosthetics (Elastomer 42, TechSil 25) seem to become harder and more brittle contrary to the other silicone (M 511) and chlorinated polyethylene (CPE) samples that become softer and more ductile. Duration of exposure increases these phenomena. CONCLUSION: The effect of irradiation time on the mechanical behavior was introduced through its effect on the models' parameters. The hypothesis was rejected since changes were observed in the model parameters.


Subject(s)
Elastomers/chemistry , Face , Prostheses and Implants , Algorithms , Compressive Strength , Dimethylpolysiloxanes/chemistry , Dimethylpolysiloxanes/radiation effects , Elastic Modulus , Elastomers/radiation effects , Hardness , Humans , Hydrocarbons, Chlorinated/chemistry , Hydrocarbons, Chlorinated/radiation effects , Materials Testing , Mechanics , Models, Chemical , Polyethylene/chemistry , Polyethylene/radiation effects , Rain , Stress, Mechanical , Sunlight , Temperature , Tensile Strength , Time Factors , Ultraviolet Rays
15.
Biomed Mater ; 4(3): 035001, 2009 Jun.
Article in English | MEDLINE | ID: mdl-19390144

ABSTRACT

The effect of UVA-UVB irradiation on the mechanical properties of three different industrial types of polydimethylsiloxane and chlorinated polyethylene samples, used in maxillofacial prostheses, was investigated in this study. Mechanical properties and thermal analysis are commonly used to determine the structural changes and mechanical strength. An aging chamber was used in order to simulate the solar radiation and assess natural aging. Compression and tensile tests were conducted on a Zwick testing machine. Durometer Shore A hardness measurements were carried out in a CV digital Shore A durometer according to ASTM D 2240. Glass transition temperature was evaluated with a differential scanning calorimeter. Simple mathematical models were developed to correlate the measured properties with irradiation time. The effect of UVA-UVB irradiation on compressive behavior affected model parameters. Significant deterioration seems to occur due to irradiation in samples.


Subject(s)
Dimethylpolysiloxanes/chemistry , Dimethylpolysiloxanes/radiation effects , Hydrocarbons, Chlorinated/chemistry , Hydrocarbons, Chlorinated/radiation effects , Nylons/chemistry , Nylons/radiation effects , Polyethylene/chemistry , Polyethylene/radiation effects , Surgery, Oral/instrumentation , Compressive Strength , Elastic Modulus , Materials Testing/methods , Mechanics , Radiation Dosage , Solar Energy , Stress, Mechanical , Tensile Strength , Ultraviolet Rays
16.
Opt Express ; 16(21): 16798-805, 2008 Oct 13.
Article in English | MEDLINE | ID: mdl-18852788

ABSTRACT

A thermally stable polymeric optical waveguide has been fabricated using ultraviolet (UV)-curable epoxy resins for the core and clad materials. A simple and cost-effective fabrication method that uses reusable polydimethylsiloxane (PDMS) masters has been developed. The 12-channel under-clad layer of the UV-cured epoxy was prepared using a PDMS master whose embossed channels had been fabricated by a polycarbonate (PC) secondary master. The thermal stability of the fabricated waveguide was tested at 200 degrees C for one hour. The optical waveguide was not damaged physically by thermal stress. Propagation losses detected by a cut-back method were 0.16 dB/cm and 0.26 dB/cm, respectively, before and after the thermal stability test at 850 nm. Loss increase after the thermal treatment can be attributed to the formation of the absorbing and scattering sources. This waveguide can be applied for areas that require thermal stability such as an optical printed-circuit board.


Subject(s)
Dimethylpolysiloxanes/chemistry , Electronics/instrumentation , Optical Devices , Dimethylpolysiloxanes/radiation effects , Equipment Design , Equipment Failure Analysis , Temperature
17.
Opt Express ; 16(17): 12715-25, 2008 Aug 18.
Article in English | MEDLINE | ID: mdl-18711510

ABSTRACT

The formation of hemispherical nanostructures and microscaled papilla by ultrafast laser irradiation was found to be a potential method to generate superhydrophbic surface of synthetic polymers. Irradiation of femtosecond laser creates roughened poly(dimethylsiloxane) (PDMS) surface in nano- and microscales, of which topography fairly well imitate a Lotus leaf in nature. The modified surface showed superhydrophobicity with a contact angle higher than 170 degrees as well as sliding angle less than 3 degrees. We further demonstrated that negative replica of the processed PDMS surface exhibit large contact angle hysteresis with a sliding angle of 90 degrees while the positive replica maintains superhydrophobicity.


Subject(s)
Dimethylpolysiloxanes/chemistry , Dimethylpolysiloxanes/radiation effects , Lasers , Nanostructures/chemistry , Nanostructures/ultrastructure , Nylons/chemistry , Nylons/radiation effects , Optics and Photonics/instrumentation , Hydrophobic and Hydrophilic Interactions , Materials Testing , Nanostructures/radiation effects , Surface Properties
18.
Langmuir ; 23(25): 12645-54, 2007 Dec 04.
Article in English | MEDLINE | ID: mdl-17979304

ABSTRACT

This article describes the fluorescence microscopy and imaging ellipsometry-based characterization of supported phospholipid bilayer formation on elastomeric substrates and its application in microcontact printing of spatially patterned phospholipid bilayers. Elastomeric stamps, displaying a uniformly spaced array of square wells (20, 50, and 100 mum linear dimensions), are prepared using poly(dimethyl)siloxane from photolithographically derived silicon masters. Exposing elastomeric stamps, following UV/ozone-induced oxidation, to a solution of small unilamellar phospholipid vesicles results in the formation of a 2D contiguous, fluid phospholipid bilayers. The bilayer covers both the elevated and depressed regions of the stamp and exhibits a lateral connectivity allowing molecular transport across the topographic boundaries. Applications of these bilayer-coated elastomeric stamps in microcontact printing of lipid bilayers reveal a fluid-tearing process wherein the bilayer in contact regions selectively transfers with 75-90% efficiency, leaving behind unperturbed patches in the depressed regions of the stamp. Next, using cholera-toxin binding fluid POPC bilayers that have been asymmetrically doped with ganglioside Gm1 ligand in the outer leaflets, we examine whether the microcontact transfer of bilayers results in the inversion of the lipid leaflets. Our results suggest a complex transfer process involving at least partial bilayer reorganization and molecular re-equilibration during (or upon) substrate transfer. Taken together, the study sheds light on the structuring of lipid inks on PDMS elastomers and provides clues regarding the mechanism of bilayer transfer. It further highlights some important differences in stamping fluid bilayers from the more routine applications of stamping in the creation of patterned self-assembled monolayers.


Subject(s)
Dimethylpolysiloxanes/chemistry , Elastomers/chemistry , Lipid Bilayers/chemistry , Membranes, Artificial , Phospholipids/chemistry , Silicones/chemistry , Dimethylpolysiloxanes/radiation effects , Elastomers/radiation effects , Lipid Bilayers/radiation effects , Microscopy, Confocal , Microscopy, Fluorescence/methods , Oxidation-Reduction , Ozone/chemistry , Particle Size , Phospholipids/radiation effects , Silicones/radiation effects , Surface Properties , Ultraviolet Rays
19.
Lab Chip ; 6(12): 1548-9, 2006 Dec.
Article in English | MEDLINE | ID: mdl-17203160

ABSTRACT

A hand-held corona treater is presented as an effective, inexpensive, and portable alternative for irreversible bonding of polydimethylsiloxane (PDMS) to glass.


Subject(s)
Dimethylpolysiloxanes/chemistry , Silicones/chemistry , Binding Sites , Costs and Cost Analysis , Dimethylpolysiloxanes/radiation effects , Electrodes , Equipment Design , Equipment Failure Analysis , Eyeglasses , Microwaves , Silicones/radiation effects , Surface Properties
20.
Langmuir ; 21(19): 8905-12, 2005 Sep 13.
Article in English | MEDLINE | ID: mdl-16142977

ABSTRACT

Surface modification of poly(dimethylsiloxane) (PDMS) was carried out via CF4 plasma treatment. The test PDMS used contains significant amounts of quartz and silica fillers, while the control material is the same PDMS with quartz removed by centrifugation. Fluorination accompanied with roughening was produced on both PDMS surfaces. With short plasma times (15 min or less), a macromolecular fluorocarbon layer was formed on the PDMS surfaces because of the dominant fluorination, leading to significant increase in F concentration, decrease of surface energy, and some roughening. With intermediate plasma times (15-30 min), dynamic balance between fluorination and ablation was achieved, leading to a plateau of the surface roughness, fluorine content, and [F-Si]/[F-C] ratio. At our longest investigated plasma time of 45 min, the plasma ablated the fluorinated covering layer on the PDMS surfaces, leading to significant increase in roughness and [F-Si]/[F-C] ratio and decrease of surface F concentration. The effect of additional quartz in the test PDMS on surface F concentration, [F-Si]/[F-C] ratio, and roughness was dramatic only when ablation was significant (i.e., 45 min). The obtained Teflon-like surface displays long-term stability as opposed to hydrophobic recovery of other plasma-treated PDMS surfaces to increase hydrophilicity. On the basis of the optimized plasma treatment time of 15 min, a microstructured PDMS mold was plasma treated and successfully used for multiple high-aspect-ratio (about 8) UV embossing of nonpolar polypropylene glycol diacrylate (PPGDA) resin.


Subject(s)
Dimethylpolysiloxanes/chemistry , Dimethylpolysiloxanes/radiation effects , Fluorocarbons/chemistry , Fluorocarbons/radiation effects , Silicones/chemistry , Silicones/radiation effects , Ultraviolet Rays , Argon/chemistry , Argon/radiation effects , Membranes, Artificial , Microscopy, Atomic Force , Quartz/chemistry , Sensitivity and Specificity , Silicon Dioxide/chemistry , Spectrophotometry , Surface Properties , Thermodynamics , X-Rays
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