Browsing by Subject "Hydroxyl group"

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Open Access
Chondrogenic differentiation of mesenchymal stem cells on glycosaminoglycan-mimetic peptide nanofibers
(American Chemical Society, 2016) Yaylaci, S .U.; Sen, M.; Bulut, O.; Arslan, E.; Güler, Mustafa O.; Tekinay, A. B.
Glycosaminoglycans (GAGs) are important extracellular matrix components of cartilage tissue and provide biological signals to stem cells and chondrocytes for development and functional regeneration of cartilage. Among their many functions, particularly sulfated glycosaminoglycans bind to growth factors and enhance their functionality through enabling growth factor-receptor interactions. Growth factor binding ability of the native sulfated glycosaminoglycans can be incorporated into the synthetic scaffold matrix through functionalization with specific chemical moieties. In this study, we used peptide amphiphile nanofibers functionalized with the chemical groups of native glycosaminoglycan molecules such as sulfonate, carboxylate and hydroxyl to induce the chondrogenic differentiation of rat mesenchymal stem cells (MSCs). The MSCs cultured on GAG-mimetic peptide nanofibers formed cartilage-like nodules and deposited cartilage-specific matrix components by day 7, suggesting that the GAG-mimetic peptide nanofibers effectively facilitated their commitment into the chondrogenic lineage. Interestingly, the chondrogenic differentiation degree was manipulated with the sulfonation degree of the nanofiber system. The GAG-mimetic peptide nanofibers network presented here serve as a tailorable bioactive and bioinductive platform for stem-cell-based cartilage regeneration studies.
Open Access
Highly sensitive determination of 2, 4, 6-trinitrotoluene and related byproducts using a diol functionalized column for high performance liquid chromatography
(Public Library of Science, 2014) Gumuscu, B.; Erdogan, Z.; Güler, Mustafa O.; Tekinay, T.
In this work, a new detection method for complete separation of 2,4,6-trinitrotoluene (TNT); 2,4-dinitrotoluene (2,4-DNT); 2,6-dinitrotoluene (2,6-DNT); 2-aminodinitrotoluene (2-ADNT) and 4-aminodinitrotoluene (4-ADNT) molecules in high-performance liquid-chromatography (HPLC) with UV sensor has been developed using diol column. This approach improves on cost, time, and sensitivity over the existing methods, providing a simple and effective alternative. Total analysis time was less than 13 minutes including column re-equilibration between runs, in which water and acetonitrile were used as gradient elution solvents. Under optimized conditions, the minimum resolution between 2,4-DNT and 2,6-DNT peaks was 2.06. The recovery rates for spiked environmental samples were between 95-98%. The detection limits for diol column ranged from 0.78 to 1.17 μg/L for TNT and its byproducts. While the solvent consumption was 26.4 mL/min for two-phase EPA and 30 mL/min for EPA 8330 methods, it was only 8.8 mL/min for diol column. The resolution was improved up to 49% respect to two-phase EPA and EPA 8330 methods. When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold. The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer, joining the formation of charge-transfer complexes with nitroaromatic compounds according to acceptor-donor interactions. Having compliance with current requirements, the proposed method demonstrates sensitive and robust separation. © 2014 Gumuscu et al.