| 11. |
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| 12. |
- Yang, Wenzhi, et al.
(författare)
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Noncovalent Functionalization of Graphene in Suspension
- 2013
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Ingår i: ISRN Organic Chemistry. - : Hindawi Limited. - 2090-5149 .- 2090-5157. ; :Article ID 656185
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Tidskriftsartikel (refereegranskat)abstract
- Suspensions of graphene, prepared from graphite foil by sonochemical exfoliation, have been treated with new nonpolar pyrenebutyric amides. The assemblies, in suspension and after deposition on solid supports, were characterized by NMR, absorption, and fluorescence spectroscopy and by transmission electron microscopy, where the well-defined shape and size of an appended [60]fulleropyrrolidine unit facilitates TEM detection of the nonstationary molecules. The accumulated evidence, also including direct comparisons of carbon nanotubes treated with pyrene amides under the same conditions, proves the successful noncovalent functionalization of graphene suspended in non-polar solvent with non-polar pyrene derivatives.
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| 13. |
- Yang, Xia, et al.
(författare)
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Development of multifunctional hyaluronic acid-based carriers by 'click' chemistry
- 2012
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : Hindawi Limited. - 1932-6254. ; 6:suppl 1, s. 191-192
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: We have developed methods to simultaneously introduce chemoselective groups to hyaluronic acid (HA) that can be crosslinked and used for immobilization of various molecules. It is easy to switch the functionalities of obtained materials through orthogonal ‘click’ chemistries.Methods: HA polymers were dually functionalized with hydrazide and thiol groups, or aldehyde groups. Different functional molecules such as bisphosphonate (BP) groups for mineralization or camptothecin (CPT) as anti-cancer drug can be linked to thiol groups. HA polymers were characterized by 1H, 31P NMR, and UV-Vis Spectroscopy. Characterizations of materials were performed using SEM, TEM, rheology, and colorimetric calcium assay.Results and discussion: The functional polymers were successfully synthesized. They can form hydrogels within 1 min with HA-aldehyde polymer. BP groups showed high affinity to calcium ions and inorganic nanoparticle phases were observed within BP containing hybrid hydrogel. On the other hand, CPT-linked HA polymer via S-S bond can self-assembled into nanoparticles, and the release of the drug is triggered by the addition of reduce agents (e.g. dithiothreitol).Conclusions: The use of orthogonal click modification opened a versatile way to prepare different kinds of HA based carriers with various functionalities by simple methods. The multifunctional HA polymers show high potentials to be used for drug delivery (pro-drug) or tissue regeneration (BP linked HA).
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| 14. |
- Yang, Xia, et al.
(författare)
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Direct ”Click” Synthesis of Hybrid Bisphosphonate-Hyaluronic Acid Hydrogel in Aqueous Solution for Biomineralization
- 2012
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 24:9, s. 1690-1697
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Tidskriftsartikel (refereegranskat)abstract
- We report the synthesis of injectable in situ forming hybrid hydrogel material and investigate its ability to support the mineralization process under mild conditions. To achieve this, we have prepared a hyaluronic acid (HA) derivative that is dually functionalized with cross-linkable hydrazide groups and bisphosphonate ligands (HA-hy-BP). The hybrid hydrogel can be formed by simple mixing of two solutions: the solution of HA-hy-BP and the Ca2+ ions containing solution of aldehyde-derivatized HA (HA-al). We found that the conjugation of BP, a P-C-P analogue of pyrophosphate, to the hydrogel matrix promotes an efficient and fast mineralization of the matrix. The mineralization is facilitated by the strong interaction between BP residues and Ca2+ ions that serve as nanometer-sized nucleation points for further calcium phosphate deposition within the HA hydrogel. Compared with previously reported hydrogel template-driven mineralization techniques, the present approach is maximally adapted for clinical settings since the formation of the hybrid takes place during quick mixing of the sterilized solutions. Moreover, the hybrid hydrogel is formed from in vivo degradable components of the extracellular matrix and therefore can be remodeled in vivo through concerted HA degradation and calcium phosphate mineralization.
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