Adenosine triphosphate (ATP) is the major carrier of chemical energy in cells. The diffusion
of ATP in hydrogels, which have a structural resemblance to the natural extracellular matrix, is
therefore of great importance to understand many biological processes. In continuation of our
recent studies of ATP diffusion in poly(ethylene glycol) diacrylate (PEG-DA) hydrogels by
pulsed field gradient nuclear magnetic resonance (PFG-NMR), we present precise diffusion
measurements of ATP in aqueous solutions of PEG-DA polymers, which are not cross-linked
to a three-dimensional network. The dependence of the ATP diffusion on the polymer volume
fraction in the hydrogels, φ, was found to be consistent with the predictions of a modified
obstruction model or the free volume theory in combination with the sieving behavior of the
polymer chains. The present measurements of ATP diffusion in aqueous solutions of the
polymers revealed that the diffusion coefficient is determined by φ only, regardless of whether
the polymers are cross-linked or not. These results seem to be inconsistent with the free volume
model, according to which voids are formed by a statistical redistribution of surrounding
molecules, which is expected to occur more frequently in the case of not cross-linked polymers.
The present results indicate that ATP diffusion takes place only in the aqueous regions of the
systems, with the volume fraction of the polymers, including a solvating water layer, being
blocked for the ATP molecules. The solvating water layer increases the effective volume of the
polymers by 66%. This modified obstruction model is most appropriate to correctly describe
the ATP diffusion in PEG-DA hydrogels.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:31633 |
| Date | 13 September 2018 |
| Creators | Majer, Günter, Southan, Alexander |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/acceptedVersion, doc-type:article, info:eu-repo/semantics/article, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 4, urn:nbn:de:bsz:15-qucosa2-315695, qucosa:31569 |
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