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Hydrogel Materials (hydrogel + material)

Distribution by Scientific Domains

Polymers and Materials Science	83%

Selected Abstracts

Rapid Generation of Biologically Relevant Hydrogels Containing Long-Range Chemical Gradients

ADVANCED FUNCTIONAL MATERIALS, Issue 1 2010
Jiankang He
Abstract Many biological processes are regulated by gradients of bioactive chemicals. Thus, the generation of materials with embedded chemical gradients may be beneficial for understanding biological phenomena and generating tissue-mimetic constructs. Here a simple and versatile method to rapidly generate materials containing centimeter-long gradients of chemical properties in a microfluidic channel is described. The formation of a chemical gradient is initiated by a passive-pump-induced forward flow and further developed during an evaporation-induced backward flow. The gradient is spatially controlled by the backward flow time and the hydrogel material containing the gradient is synthesized via photopolymerization. Gradients of a cell-adhesion ligand, Arg-Gly-Asp-Ser (RGDS), are incorporated in poly(ethylene glycol)-diacrylate (PEG-DA) hydrogels to test the response of endothelial cells. The cells attach and spread along the hydrogel material in a manner consistent with the RGDS-gradient profile. A hydrogel containing a PEG-DA concentration gradient and constant RGDS concentration is also shown. The morphology of cells cultured on such hydrogel changes from round in the lower PEG-DA concentration regions to well-spread in the higher PEG-DA concentration regions. This approach is expected to be a valuable tool to investigate the cell,material interactions in a simple and high-throughput manner and to design graded biomimetic materials for tissue engineering applications. [source]

Periodic Micropatterning of Polyethylene Glycol Diacrylate Hydrogel by Laser Interference Lithography Using Nano- and Femtosecond Pulsed Lasers,

ADVANCED ENGINEERING MATERIALS, Issue 3 2009
Andrés F. Lasagni
In this article, we report on the fabrication of periodic arrays using multibeam laser interference patterning (MLI) with both nanosecond and femtosecond lasers on hydrogel materials. Configurations involving two, four, and five laser beams were utilized being able to produce a wide range of periodic arrays. [source]

High-Resolution Patterning of Hydrogels in Three Dimensions using Direct-Write Photofabrication for Cell Guidance

ADVANCED FUNCTIONAL MATERIALS, Issue 22 2009
Stephanie K. Seidlits
Abstract The development of three-dimensional, spatially defined neuronal cultures that mimic chemical and physical attributes of native tissue is of considerable interest for various applications, including the development of tailored neuronal networks and clinical repair of damaged nerves. Here, the use of multiphoton excitation to photocrosslink protein microstructures within three-dimensional, optically transparent hydrogel materials, such as those based on hyaluronic acid, is reported. Multiphoton excitation confines photocrosslinking to a three-dimensional voxel with submicron spatial resolution, enabling fabrication of protein matrices with low- to sub-micrometer feature sizes by scanning the focus of a laser relative to the reagent solution. These methods can be used to create complex three-dimensional architectures that provide both chemical and topographical cues for cell culture and guidance, providing for the first time a means to direct cell adhesion and migration on size scales relevant to in vivo environments. Using this approach, guidance of both dorsal root ganglion cells (DRGs) and hippocampal neural progenitor cells (NPCs) along arbitrary, three-dimensional paths is demonstrated. [source]

Biodegradable Polymer Crosslinker: Independent Control of Stiffness, Toughness, and Hydrogel Degradation Rate

ADVANCED FUNCTIONAL MATERIALS, Issue 19 2009
Chaenyung Cha
Abstract Hydrogels are being increasingly studied for use in various biomedical applications including drug delivery and tissue engineering. The successful use of a hydrogel in these applications greatly relies on a refined control of the mechanical properties including stiffness, toughness, and the degradation rate. However, it is still challenging to control the hydrogel properties in an independent manner due to the interdependency between hydrogel properties. Here it is hypothesized that a biodegradable polymeric crosslinker would allow for decoupling of the dependency between the properties of various hydrogel materials. This hypothesis is examined using oxidized methacrylic alginate (OMA). The OMA is synthesized by partially oxidizing alginate to generate hydrolytically labile units and conjugating methacrylic groups. It is used to crosslink poly(ethylene glycol) methacrylate and poly(N -hydroxymethyl acrylamide) to form three-dimensional hydrogel systems. OMA significantly improves rigidity and toughness of both hydrogels as compared with a small molecule crosslinker, and also controls the degradation rate of hydrogels depending on the oxidation degree, without altering their initial mechanical properties. The protein-release rate from a hydrogel and subsequent angiogenesis in vivo are thus regulated with the chemical structure of OMA. Overall, the results of this study suggests that the use of OMA as a crosslinker will allow the implantation of a hydrogel in tissue subject to an external mechanical loading with a desired protein-release profile. The OMA synthesized in this study will be, therefore, highly useful to independently control the mechanical properties and degradation rate of a wide array of hydrogels. [source]

Layer-by-Layer Hydrogen-Bonded Polymer Films: From Fundamentals to Applications

ADVANCED MATERIALS, Issue 30 2009
Eugenia Kharlampieva
Abstract Recent years have seen increasing interest in the construction of nanoscopically layered materials involving aqueous-based sequential assembly of polymers on solid substrates. In the booming research area of layer-by-layer (LbL) assembly of oppositely charged polymers, self-assembly driven by hydrogen bond formation emerges as a powerful technique. Hydrogen-bonded (HB) LbL materials open new opportunities for LbL films, which are more difficult to produce than their electrostatically assembled counterparts. Specifically, the new properties associated with HB assembly include: 1) the ease of producing films responsive to environmental pH at mild pH values, 2) numerous possibilities for converting HB films into single- or two-component ultrathin hydrogel materials, and 3) the inclusion of polymers with low glass transition temperatures (e.g., poly(ethylene oxide)) within ultrathin films. These properties can lead to new applications for HB LbL films, such as pH- and/or temperature-responsive drug delivery systems, materials with tunable mechanical properties, release films dissolvable under physiological conditions, and proton-exchange membranes for fuel cells. In this report, we discuss the recent developments in the synthesis of LbL materials based on HB assembly, the study of their structure,property relationships, and the prospective applications of HB LbL constructs in biotechnology and biomedicine. [source]

Contact lenses as a drug delivery device for epidermal growth factor in the treatment of ocular wounds

CLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 2 2010
Clyde L Schultz PhD
Background:, This work was conducted to investigate the uptake and release of epidermal growth factor (EGF) from hydrogel contact lenses and to determine whether the released protein would be therapeutically active in a rabbit corneal epithelial defect model of ocular trauma, prior to use in humans. Methods:, The uptake and release of EGF from hydrogel contact lens materials were determined by high-pressure liquid chromatography. Contact lenses composed of vasurfilcon A or lotrafilcon A (containing silicone) were incubated in a source solution containing 0.4 ppm EGF for seven hours. To determine the kinetics of drug uptake into the contact lens matrix, drug concentration in the source solution was measured at zero, one, 60, 240 and 420 minutes. To determine the kinetics of release, loaded contact lenses were immersed in a recipient solution of phosphate-buffered saline. Therapeutic activity in vivo was investigated by placing prepared lenses on the surface of abraded corneas of New Zealand White rabbits, with abraded corneas of contralateral eyes used as controls. Control eyes were treated with contact lenses placed in saline for injection. Wound closure was assessed hourly. Results:, Uptake and release of EGF were demonstrated for vasurfilcon A but not lotrafilcon A contact lens materials. The retention time of EGF released from vasurfilcon A contact lenses was similar to control EGF not exposed to contact lens polymers. The greatest adsorption of EGF into the lens material occurred within approximately 120 minutes, with a flattening of the rate of uptake thereafter. Abraded eyes in rabbits showed a significantly higher overall healing rate for EGF-treated contact lenses compared with control eyes (p < 0.0001). Conclusions:, EGF can be delivered from some but not all hydrogel materials. Lens materials composed of silicone may not be useful for delivering EGF to the eye. EGF-treated contact lenses may be a useful device to facilitate healing of ocular wounds. [source]