Biological characterization of hydrogels of poly(vinyl alcohol) and hyaluronic acid

Guerra, R Sbarbati Del; Cascone, Maria Grazia; Barbani, Niccoletta; Lazzeri, Luigi

doi:10.1007/bf00120341

Cited by 26 publications

(5 citation statements)

References 5 publications

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“…Cell culture experiments have demonstrated that, without coagulation, hydrogels with one freeze‐thaw cycle were not stable enough to sustain cell culture, because fast degradation compromises the pH of the culture medium. Low cell adhesion was reported before for composite hydrogels without coagulation treatment,38 which might be attributed to this fact. PVA hydrogels themselves demonstrated very low cell attachment and only a few cells were observed after 10 days of culture, which further demonstrated the necessity of inclusion of substitutes.…”

Section: Discussionmentioning

confidence: 83%

Physically crosslinked composite hydrogels of PVA with natural macromolecules: Structure, mechanical properties, and endothelial cell compatibility

et al. 2009

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Polyvinyl alcohol (PVA) hydrogels have been considered potentially suitable for applications as engineered blood vessels because of their structure and mechanical properties. However, PVA's hydrophilicity hinders its capacity to act as a substrate for cell attachment. As a remedy, PVA was blended with chitosan, gelatin, or starch, and hydrogels were formed by subjecting the solutions to freeze-thaw cycles followed by coagulation bath immersion. The structure-property relationships for these hydrogels were examined by measurement of their swelling, rehydration, degradation, and mechanical properties. For the case of pure PVA hydrogels, the equilibrium swelling ratio was used to predict the effect of freeze thaw cycles and coagulation bath on average molecular weights between crosslinks and on mesh size. For all hydrogels, trends for the reswelling ratio, which is indicative of the crosslinked polymer fraction, were consistent with relative tensile properties. The coagulation bath treatment increased the degradation resistance of the hydrogels significantly. The suitability of each hydrogel for cell attachment and proliferation was examined by protein adsorption and bovine vascular endothelial cell culture experiments. Protein adsorption and cell proliferation was highest on the PVA/gelatin hydrogels. This study demonstrates that the potential of PVA hydrogels for artificial blood vessel applications can be improved by the addition of natural polymers, and that freeze-thawing and coagulation bath treatment can be utilized for fine adjustment of the physical characteristics.

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Section: Discussionmentioning

confidence: 83%

Physically crosslinked composite hydrogels of PVA with natural macromolecules: Structure, mechanical properties, and endothelial cell compatibility

et al. 2009

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“…2. 2000 term in vivo animal studies and in vitro cell culture studies (23,24). However, further studies would have to be conducted to prove the biocompatibility of PVA in the cochlea as well as in soft tissue before clinical use with cochlear implants.…”

Section: Discussionmentioning

confidence: 99%

Comparison of electrode position in the human cochlea using various perimodiolar electrode arrays

Tykocinski

Cohen

Pyman

et al. 2000

American Journal of Otolaryngology

112

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Objective: This study was conducted to evaluate the insertion properties and intracochlear trajectories of three perimodiolar electrode array designs and to compare these designs with the standard CochlearlMelbourne array. Background: Advantages to be expected of a perimodiolar electrode array inclu<;le both a reduction in stimulus thresholds and an increase in dynamic range, resulting in a more localized stimulation pattern of the spiral ganglion cells, reduced power consumption, and, therefore, longer speech processor battery life. Methods: The test arrays were implanted into human temporal bones. Image analysis was performed on a radiograph taken after the insertion. The cochleas were then histologically processed with the electrode array in situ, and the resulting sections were subsequently assessed for position of the electrode array as well as insertion-related intracochlear damage. Intracochlear multichannel cochlear implants have successfully provided auditory information for profoundly deaf patients by electrically stimulating discrete populations of auditory nerve fibers via a scala tympani electrode array. The straight, yet flexible, tapered Melbourne/Cochlear electrode array can be safely implanted into the human cochlea. However, histologic and radiologic examination of implanted temporal bones showed that the electrode array is usually positioned along the outer wall of the scala tympani (1-5). The array is, therefore, some distance from the spiral ganglion cells in the Rosenthal canal and their peripheral processes. However,

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“…To limit the diffusion of the product so that it remained in the immediate vicinity of the bound enzyme on the array, we applied the enzyme substrate in a thin coating of PVA. PVA is nonfluorescent, optically transparent, water-soluble, and highly viscous and has applications in many biological assays. , The diffusion coefficient of fluorescein in a layer of 5% PVA in phosphate buffer was measured via fluorescence recovery after photobleaching (FRAP) and found to be ∼50 μm 2 /s, roughly 6-fold slower than in phosphate buffer without PVA (Supporting Information Figure S1). As shown in Figure d, it was relatively easy to resolve the enzyme activity in the spots with little cross contamination.…”

Section: Resultsmentioning

confidence: 99%

Exploring Peptide Space for Enzyme Modulators

Cai

Johnston

et al. 2010

J. Am. Chem. Soc.

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Enzymes which regulate the metabolic reactions for sustaining all living things, are the engines of life. The discovery of molecules that are able to control enzyme activity is of great interest for therapeutics and the biocatalysis industry.Peptides are promising enzyme modulators due to their large chemical diversity and the existence of well-established methods for library synthesis.Microarrays represent a powerful tool for screening thousands of molecules, on a small chip, for candidates that interact with enzymes and modulate their functions. In this work, a method is presented for screening highdensity arrays to discover peptides that bind and modulate enzyme activity. A viscous polyvinyl alcohol (PVA) solution was applied to array surfaces to limit the diffusion of product molecules released from enzymatic reactions, allowing the simultaneous measurement of enzyme activity and binding at each peptide feature. For proof of concept, it was possible to identify peptides that bound to horseradish peroxidase (HRP), alkaline phosphatase (APase) and β-galactosidase (β-Gal) and substantially alter their activities by comparing the peptide-enzyme binding levels and bound enzyme activity on microarrays.Several peptides, selected from microarrays, were able to inhibit β-Gal in solution, which demonstrates that behaviors selected from surfaces often transfer to solution. A mechanistic study of inhibition revealed that some of the selected peptides inhibited enzyme activity by binding to enzymes and inducing aggregation.PVA-coated peptide slides can be rapidly analyzed, given an appropriate enzyme assay, and they may also be assayed under various conditions (such as temperature, pH and solvent). I have developed a general method to discover ii molecules that modulate enzyme activity at desired conditions. As demonstrations, some peptides were able to promote the thermal stability of bound enzyme, which were selected by performing the microarray-based enzyme assay at high temperature. For broad applications, selected peptide ligands were used to immobilize enzymes on solid surfaces. Compared to conventional methods, enzymes immobilized on peptide-modified surfaces exhibited higher specific activities and stabilities. Peptide-modified surfaces may prove useful for immobilizing enzymes on surfaces with optimized orientation, location and performance, which are of great interest to the biocatalysis industry.

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Biological characterization of hydrogels of poly(vinyl alcohol) and hyaluronic acid

Cited by 26 publications

References 5 publications

Physically crosslinked composite hydrogels of PVA with natural macromolecules: Structure, mechanical properties, and endothelial cell compatibility

Physically crosslinked composite hydrogels of PVA with natural macromolecules: Structure, mechanical properties, and endothelial cell compatibility

Comparison of electrode position in the human cochlea using various perimodiolar electrode arrays

Exploring Peptide Space for Enzyme Modulators

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