Golden hydrogel - hydrogels visible for µCT imaging in tissue engineering
Nehar Celikkin , Karol Szlązak , Jakub Jaroszewicz , Wojciech Święszkowski
AbstractINTRODUCTION: When employing imaging modalities to evaluate in vivo response to implanted biomaterials, it is crucial to make quantifiable diagnostic conclusions about the biomaterial-host interactions and degree of tissue repair. MicroCT (µCT) is a commonly used imaging technique that provides high resolution and non-invasive visualization for hard tissue, especially the microarchitecture, volume, surface area, tissue thickness and spatial distribution. In our study, we aim to create µCT visible hydrogels for longitudinal tracking of scaffold degradation and tissue formation. METHODS: Synthesis of GelMA: GelMA was synthesized as described previously. Briefly, type A porcine skin gelatin was mixed at 10% (w/v) into PBS. Methacrylic anhydride was added to gelatin solution and allowed to react for 3h. The mixture was dialyzed against distilled water to remove unreacted methacrylic acid. The solution was lyophilized and stored at -80 °C until further use. Integrating Au NPs to GelMA scaffolds: Commericially available Au NPs were dispersed in 10% GelMA solution containing 0.5% photoinitiator (Irgacure 2959). 100 µL of GelMAAu NP solution has been transferred into molds and crosslinked with UV light. Synthesis of thiol functionalized GelMA: Due to the strong interaction between Au and –SH groups, GelMA has been functionalized with thiol groups. Thiolated GelMA was synthesized by covalent modification of amino groups of GelMA by the addition of sulfhydryl moieties. 1% of GelMA solution was prepared and varying amounts of thioglycolic acid added to the solution. Any unreacted thioglycolic acid residue was removed by repeated dialysis steps. The purified thiolated gelatin was freeze-dried and stored at -80 °C for further use. The –SH modified GelMA has been mixed with Au NPs and scaffolds have been prepared as described before. RESULTS: After the Au NPs blended with GelMA solution, the solution has been transferred into molds and UV crosslinked. Following this step, the hydrogels were scanned via µCT in wet state. Further on, the gels were freeze-dried and rescanned in dry state. Tomograms of the hydrogels and Au NP carrying hydrogels were analysed in Image J. The histograms of each sample have been plotted according to the grayscale values in chosen region of interest (Fig.1). Fig. 1: µCT scans and contrast histograms of GelMA and GelMA-Au NP hydrogels in wet and dry state We have observed a complete overlay on attenuation values on tomograms when GelMA is on wet state regardless of Au NPs. However in dry state, the shift to higher attenuation has been observed due to the presence of the Au NPs. DISCUSSION & CONCLUSIONS: In our study we have observed the desired contrast for GelMA hydrogels can be achieved by using Au NPs in dry state, however, the dilution of Au NPs, due to the high water content of the hydrogels, eliminates the contrast difference. More effective binding of Au NPs to GelMA is going to be further studied. REFERENCES: 1 J.E. Trachtenberg, T.N. Vo, A.G. Mikos, Pre-clinical Characterization of Tissue Engineering Constructs for Bone and Cartilage Regeneration, Ann. Biomed. Eng. 43 (2014) 681–696.2 I. Van Den Bulcke, B. Bogdanov, N. De Rooze, E.H. Schacht, M. Cornelissen, H. Berghmans, Structural and rheological properties of methacrylamide modified gelatin hydrogels., Biomacromolecules. 1 (2000) 31–8. 3 H. Häkkinen, The gold-sulfur interface at the nanoscale., Nat. Chem. 4 (2012) 443–55.4 L.M.Y. Yu, K. Kazazian, M.S. Shoichet, Peptide surface modification of methacrylamide chitosan for neural tissue engineering applications, J. Biomed. Mater. Res. Part A. (2007). ACKNOWLEDGEMENTS: The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013/ under REA grant agreement No. 607868 (iTERM).
|Journal series||European Cells & Materials, ISSN 1473-2262|
|Publication size in sheets||0.3|
|ASJC Classification||; ; ; ;|
|Publication indicators||= 0; : 2016 = 1.28; : 2016 = 3.343 (2) - 2016=4.803 (5)|
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