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Polymers 2013, 5(4), 1241-1257; doi:10.3390/polym5041241
Article

Release of Potassium Ion and Calcium Ion from Phosphorylcholine Group Bearing Hydrogels

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Received: 28 September 2013; in revised form: 17 October 2013 / Accepted: 25 October 2013 / Published: 11 November 2013
(This article belongs to the Special Issue Biomimetic Polymers)
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Abstract: In an attempt to recreate the microenvironment necessary for directed hematopoietic stem cell differentiation, control over the amount of ions available to the cells is necessary. The release of potassium ion and calcium ion via the control of cross-linking density of a poly(2-hydroxyethyl methacrylate) (pHEMA)-based hydrogel containing 1 mol % 2-methacryloyloxyethyl phosphorylcholine (MPC) and 5 mol % oligo(ethylene glycol) (400) monomethacrylate [OEG(400)MA] was investigated. Tetra(ethylene glycol) diacrylate (TEGDA), the cross-linker, was varied over the range of 1–12 mol %. Hydrogel discs (ϕ = 4.5 mm and h = 2.0 mm) were formed by UV polymerization within silicone isolators to contain 1.0 M CaCl2 and 0.1 M KCl, respectively. Isothermal release profiles, were measured at 37 °C in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid sodium salt (HEPES) buffer using either calcium ion or potassium ion selective electrodes (ISE). The resulting release profiles were found to be independent of cross-linking density. Average (n = 3) release profiles were fit to five different release models with the Korsmeyer-Peppas equation, a porous media transport model, exhibiting the greatest correlation (R2 > 0.95). The diffusion exponent, n was calculated to be 0.24 ± 0.02 and 0.36 ± 0.04 for calcium ion and potassium ion respectively indicating non-Fickian diffusion. The resulting diffusion coefficients were calculated to be 2.6 × 10−6 and 11.2 × 10−6 cm2/s, which compare well to literature values of 2.25 × 10−6 and 19.2 × 10−6 cm2/s for calcium ion and potassium ion, respectively.
Keywords: calcium ion; potassium ion; diffusion; 2-methacryloyloxyethyl phosphorylcholine; poly(2-hydroxyethyl methacrylate); hydrogel matrix; Zwitterionic; HEMA calcium ion; potassium ion; diffusion; 2-methacryloyloxyethyl phosphorylcholine; poly(2-hydroxyethyl methacrylate); hydrogel matrix; Zwitterionic; HEMA
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Aucoin, H.R.; Wilson, A.N.; Wilson, A.M.; Ishihara, K.; Guiseppi-Elie, A. Release of Potassium Ion and Calcium Ion from Phosphorylcholine Group Bearing Hydrogels. Polymers 2013, 5, 1241-1257.

AMA Style

Aucoin HR, Wilson AN, Wilson AM, Ishihara K, Guiseppi-Elie A. Release of Potassium Ion and Calcium Ion from Phosphorylcholine Group Bearing Hydrogels. Polymers. 2013; 5(4):1241-1257.

Chicago/Turabian Style

Aucoin, Hanna R.; Wilson, A. N.; Wilson, Ann M.; Ishihara, Kazuhiko; Guiseppi-Elie, Anthony. 2013. "Release of Potassium Ion and Calcium Ion from Phosphorylcholine Group Bearing Hydrogels." Polymers 5, no. 4: 1241-1257.


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