Jöns Hilborn - Academia.edu (original) (raw)

Papers by Jöns Hilborn

Open Research Online (The Open University), 2007

Acta biomaterialia, Jan 28, 2016

To strengthen the mechanical properties of a fibrin gel and improve its applicability as a scaffo... more To strengthen the mechanical properties of a fibrin gel and improve its applicability as a scaffold for tissue engineering (TE) applications, a strategy for the in situ preparation of the interpenetrating network (IPN) of fibrin and hyaluronic acid (HA) was developed on the basis of simultaneous and orthogonal fibrinogenesis and disulfide cross-linking. The synthetic pathway included the preparation of mutually reactive HA derivatives bearing thiol and 2-dithiopyridyl groups. Combining thiol-derivatized HA with thrombin and 2-dithiopyridyl-modified HA with fibrinogen and then mixing the obtained liquid formulations afforded IPNs with fibrin-resembling fibrillar architectures at different ratios between fibrin and HA networks. The formation of two networks was confirmed by conducting reference experiments with the compositions lacking one of the four components. The composition of 2% (w/v) fibrin and 1% (w/v) HA showed the highest storage modulus (G'), as compared with the single...

Acta Biomaterialia, 2016

Tracking of degradation of hydrogels-based biomaterials in vivo is very important for rational de... more Tracking of degradation of hydrogels-based biomaterials in vivo is very important for rational design of tissue engineering scaffolds that act as delivery carriers for bioactive factors. During the process of tissue development, an ideal scaffold should remodel at a rate matching with scaffold degradation. To reduce amount of animals sacrificed, non-invasive in vivo imaging of biomaterials is required which relies on using of biocompatible and in situ gel forming compounds carrying suitable imaging agents. In this study we developed a method of in situ fabrication of fluorescently labeled and injectable hyaluronan (HA) hydrogel based on one pot sequential use of Michael addition and thiol-disulfide exchange reactions for the macromolecules labeling and cross-linking respectively. Hydrogels with different content of HA were prepared and their enzymatic degradation was followed in vitro and in vivo using fluorescence multispectral imaging. First, we confirmed that the absorbance of the matrix-linked near-IR fluorescent IRDye® 800CW agent released due to the matrix enzymatic degradation in vitro matched the amount of the degraded hydrogel measured by classical gravimetric method. Secondly, the rate of degradation was inversely proportional to the hydrogel concentration and this structure-degradation relationship was similar for both in vitro and in vivo studies. It implies that the degradation of this disulfide cross-linked hyaluronan hydrogel in vivo can be predicted basing on the results of its in vitro degradation studies. The compliance of in vitro and in vivo methods is also promising for the future development of predictive in vitro tissue engineering models. The need for engineered hydrogel scaffolds that deliver bioactive factors to endogenous progenitor cells in vivo via gradual matrix resorption and thus facilitate tissue regeneration is increasing with the aging population. Importantly, scaffold should degrade at a modest rate that will not be too fast to support tissue growth nor too slow to provide space for tissue development. The present work is devoted to longitudinal tracking of a hydrogel material in vivo from the time of its implantation to the time of complete resorption without sacrificing animals. The method demonstrates correlation of resorption rates in vivo and in vitro for hydrogels with varied structural parameters. It opens the possibility to develop predictive in vitro models for tissue engineered scaffolds and reduce animal studies.

MRS Proceedings, 1997

ABSTRACTZinc sulphide (ZnS) particles are efficient phosphors for application in flat-panel displ... more ABSTRACTZinc sulphide (ZnS) particles are efficient phosphors for application in flat-panel displays. Spherical ZnS particles were prepared by precipitation from a homogeneous solution. Nanoparticles of 20 to 40 nm having a very narrow size distribution could be synthesized by using complexing chelates such as acetate and acetylacetonate. Complexing of the precipitating cation with the anions present in the system lead to a limited concentration of free cations in the solution. This strongly influences the kinetics of the primary particle agglomeration/growth, resulting in nanometer-sized ZnS particles. Nanostructured ZnS synthesized in this way are polycrystalline particles composed of crystallites of 5–10 nm. The synthesis of very small, non-agglomerated, nanocrystalline particles in the 5–10 nm size range was also possible, making use of a strong complexing ligand (thioglycerol) during the synthesis. The synthesis of controlled monosized ZnS particles will be presented and discus...

The Journal of Physical Chemistry B, 2000

ABSTRACT Iron alginate gel beads were prepared starting from sodium alginate solutions. Fe comple... more ABSTRACT Iron alginate gel beads were prepared starting from sodium alginate solutions. Fe complexed with carboxylate is active during the Fenton-enhanced decoloration/degradation of Orange II via the encapsulated Fe catalyst. By energy-dispersive X-ray microanalysis (EDX) it was shown that a significant amount of Fe was on the catalyst surface and only a smaller fraction inside the cross-linked Fe alginate. The Fe alginate beads were 2 mm in diameter containing highly dispersed Fe species with sizes of about 0.5 nm. The Fe alginate mediated decoloration of Orange II takes place in less than an hour in the presence of H2O2 under visible light irradiation, at pH values between 5 and 8. Repetitive decoloration of Orange II solutions was observed by addition of the azo dye at the beginning of each cycle.

Macromolecules, 1990

Page 1. 2854 Macromolecules 1990,23, 2854-2861 (17) Sato, M.; Tanaka, S.; Kaeriyama, K. J. J. Che... more Page 1. 2854 Macromolecules 1990,23, 2854-2861 (17) Sato, M.; Tanaka, S.; Kaeriyama, K. J. J. Chem. Soc., Chem. (18) Bryce, MR; Chissel, A.; Kathirgamanatan, P.; Parker, D.; (19) Masuda. H.: Tanaka. S.: Kaerivama. K. J . Chem. Soc.. Chem. Commun. 1986,873. ...

Macromolecules, 2000

Journal of Polymer Science Part A: Polymer Chemistry, 1990

Journal of Applied Polymer Science, 2000

It is also possible that your web browser is not configured or not able to display style sheets. ... more It is also possible that your web browser is not configured or not able to display style sheets. In this case, although the visual presentation will be degraded, the site should continue to be functional. We recommend using the ...

Journal of Applied Polymer Science, 2007

In this study we describe the development of an injectable, in situ chemical hydrogel forming sys... more In this study we describe the development of an injectable, in situ chemical hydrogel forming system. The gelation occurs under neutral pH and at room temperature immediately upon mixing of the two aqueous poly (vinyl alcohol) components specifically derivatized through carbamate linkages with aldehyde (PVA‐AL) and hydrazide (PVA‐HY) functional groups, respectively. Aldehyde and hydrazide pendant groups were incorporated with a low degree of substitution (DS) into the PVA backbone to keep PVA structural homogeneity minimally altered. As a result, the hydrazone crosslinks are formed rapidly between aldehyde and hydrazide pendant groups when the correspondingly modified PVA components are brought in contact as water solutions. To assess in situ hydrazone crosslinks formation for in vitro cytocompatibility, murine neuroblastoma N2a cells were suspended in cell culture medium with the dissolved PVA‐HY prior to addition to the PVA‐AL aqueous solution. Thus, the cells were chemically enca...

Journal of Applied Polymer Science, 2006

The dry–jet–wet spinning process was employed to spin poly(lactic acid)(PLA) fiber by the phase i... more The dry–jet–wet spinning process was employed to spin poly(lactic acid)(PLA) fiber by the phase inversion technique using chloroform and methanol as solvent and nonsolvent, respectively, for PLA. The as spun fiber was subjected to two‐stage hot drawing to study the effect of various process parameters, such as take‐up speed, drawing temperature, and heat‐setting temperature on the fiber structural properties. The take‐up speed had a pronounced influence on the maximum draw ratio of the fiber. The optimum drawing temperature was observed to be 90°C to get a fiber with the tenacity of 0.6 GPa for the draw ratio of 8. The heat‐setting temperature had a pronounced effect on fiber properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3774–3780, 2006

Biotechnology and Bioengineering, 2000

Our spinning disk atomization (SDA) can, relative to other existing techniques, produce micron-si... more Our spinning disk atomization (SDA) can, relative to other existing techniques, produce micron-sized particles with very narrow size distribution. The aim of this work is to present this technology for the production of alginate microspheres and microcapsules. We atomized and gelled aqueous alginate solutions into very narrowly dispersed microspheres with sizes ranging from 300 to 600 microm. Here, the interest is to produce, at high rate, particles of a given size with a narrow size distribution and also to show a new method of encapsulation using SDA. The viscosity and flow rate contributions in the drop formation is qualitatively analyzed to show how they affect droplet size. In addition, a technique for high degree of encapsulation is presented in which yeast is used as a model system. The production of yeast-loaded microspheres by SDA shows the potential of the technique for biotechnology applications.

Biosensors and Bioelectronics, 2004