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001-es BibID:BIBFORM056650
Első szerző:Bányai István (vegyész)
Cím:Self-diffusion of water and poly(amidoamine) dendrimers in dilute aqueous solutions / Bányai István, Kéri Mónika, Nagy Zoltán, Berka Márta, Balogh Lajos P.
Megjegyzések:Medium generation PAMAM dendrimers are extensively researched as drug delivery vehicles therefore detailed knowledge of their physico-chemical properties in solution is vital. We have selected ethylenediamine core, generation five poly(amidoamine)(PAMAM_E5) dendrimers (amine terminated PAMAM_E5.NH2 and its succinamic acid derivative PAMAM_E5.SAH, respectively) as model compounds to study their dynamic behavior in water as a function of pH and concentration. Diffusion coefficients of water and the dendrimers were determined in deuterium oxide using pulse-field gradient stimulated echo (PGSE) NMR. The diffusion rate for PAMAM_E5.NH2 increased monotonously with increasing pH values while for PAMAM_E5.SAH a maximum was found at an isoelectric value of pH ? 5.7. The apparent diffusion coefficients of dendrimers decreased linearly with increasing concentration measured at their self-pH (pH ? 9.4 for PAMAM_E5.NH2 and pH ? 5.7 for PAMAM_E5.SAH) in the absence of added salts. The observations could be explained by considering hard sphere interactions between strongly hydrated dendrimer molecules. The average hydrodynamic radii of dendrimers were determined by extrapolating the measured diffusion coefficients to zero dendrimer concentration and applying the Stokes?Einstein equation. The calculated values were RH ? 3.05 0.04 nm for PAMAM_E5.NH2 and RH ? 3.37 0.08 nm for PAMAM_E5.SAH respectively. Measured diffusion coefficients of water (D2O) also decreased linearly with increasing dendrimer concentration. From the concentration dependence, the average number of water molecules that form one dynamic unit with one macromolecule could be calculated on the basis of three different obstruction models. It has been concluded that hydrated PAMAM dendrimers in aqueous solutions behave as soft colloids against solvent molecules but as hard-sphere colloids against each other. Their equivalent hard-sphere radii were found to be equal to the measured hydrodynamic radii.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
poli(amidoamin) dendrimer
hard sphere colloid
hydration number
Megjelenés:Soft Matter. - 9 : 5 (2013), p. 1645-1655. -
További szerzők:Kéri Mónika (1984-) (környezetkutató vegyész) Nagy Zoltán (1974-) (vegyész) Berka Márta (1949-) (vegyész) Balogh Lajos P.
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001-es BibID:BIBFORM082186
Első szerző:Kéri Mónika (környezetkutató vegyész)
Cím:Beware of phosphate: evidence of specific dendrimer-phosphate interactions / Mónika Kéri, Zoltán Nagy, Levente Novák, Edit Szarvas, Lajos P. Balogh, István Bányai
ISSN:1463-9076 1463-9084
Megjegyzések:Dendrimers are extensively studied for drug delivery and catalysis, most of which are pH dependent. Phosphate buffer solutions (PBSs) are often used to adjust the pH. We have found that phosphate ions become incorporated into poly(amidoamine) (PAMAM) dendrimer molecules by forming H-bonds with tertiary nitrogens. We show that this specific interaction between H2PO4- and HPO42- ions and generation five PAMAM dendrimers causes a decrease in hydrodynamic size, disturbing the outcome of the size exclusion chromatography analysis. We monitored this interaction by 1H and 31P high resolution NMR, NMR-diffusiometry, pH-potentiometry and infrared spectroscopy. Failing to take into account this effect may lead to incorrect conclusions and misinterpreting interactions of PAMAM dendrimers with drug molecules and subsequently incorrect dosing. The phosphate salts of amino terminated generation five PAMAM dendrimers are stable for years when stored in the dark, even in dilute aqueous solutions, which has important implications for the shelf-life of dendrimer-based drug delivery systems.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Physical Chemistry Chemical Physics. - 19 : 18 (2017), p. 11540-11548. -
További szerzők:Nagy Zoltán (1974-) (vegyész) Novák Levente (1967-) (biológus) Szarvas Edit Balogh Lajos P. Bányai István (1953-) (vegyész)
Pályázati támogatás:GINOP-2.3.2-15-2016-00008
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