Kinetic Analysis of the Uptake and Release of Fluorescein by Metal-Organic Framework Nanoparticles
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Faculty of Physics and Center for NanoScience (CeNS), LMU Munich, Geschwister-Scholl-Platz 1, 80539 Munich, Germany
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Department of Chemistry and Center for NanoScience (CeNS), LMU Munich, Butenandtstraße 11 (E), 81377 Munich, Germany
*
Authors to whom correspondence should be addressed.
Academic Editor: Claudio Pettinari
Materials 2017, 10(2), 216; https://doi.org/10.3390/ma10020216
Received: 29 November 2016
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Revised: 3 February 2017
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Accepted: 9 February 2017
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Published: 22 February 2017
(This article belongs to the Special Issue Metal Organic Framework Materials)
Metal-organic framework nanoparticles (MOF NPs) are promising guest-host materials with applications in separation, storage, catalysis, and drug delivery. However, on- and off-loading of guest molecules by porous MOF nanostructures are still poorly understood. Here we study uptake and release of fluorescein by two representative MOF NPs, MIL-100(Fe) and MIL-101(Cr). Suspensions of these MOF NPs exhibit well-defined size distributions and crystallinity, as verified by electron microscopy, dynamic light scattering, and X-ray diffraction. Using absorbance spectroscopy the equilibrium dissociation constants and maximum numbers of adsorbed fluorescein molecules per NP were determined. Time-resolved fluorescence studies reveal that rates of release and loading are pH dependent. The kinetics observed are compared to theoretical estimates that account for bulk diffusion into NPs, and retarded internal diffusion and adsorption rates. Our study shows that, rather than being simple volumetric carriers, MOF-NPs are dominated by internal surface properties. The findings will help to optimize payload levels and develop release strategies that exploit varying pH for drug delivery.
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Keywords:
metal organic framework; nanoparticle; loading and release
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MDPI and ACS Style
Preiß, T.; Zimpel, A.; Wuttke, S.; Rädler, J.O. Kinetic Analysis of the Uptake and Release of Fluorescein by Metal-Organic Framework Nanoparticles. Materials 2017, 10, 216. https://doi.org/10.3390/ma10020216
AMA Style
Preiß T, Zimpel A, Wuttke S, Rädler JO. Kinetic Analysis of the Uptake and Release of Fluorescein by Metal-Organic Framework Nanoparticles. Materials. 2017; 10(2):216. https://doi.org/10.3390/ma10020216
Chicago/Turabian StylePreiß, Tobias, Andreas Zimpel, Stefan Wuttke, and Joachim O. Rädler. 2017. "Kinetic Analysis of the Uptake and Release of Fluorescein by Metal-Organic Framework Nanoparticles" Materials 10, no. 2: 216. https://doi.org/10.3390/ma10020216
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