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Multi-stimuli responsive block copolymers as a smart release platform for a polypyridyl ruthenium complex

Appold, M. and Mari, C. and Lederle, C. and Elbert, J. and Schmidt, C. and Ott, I. and Stühn, B. and Gasser, G. and Gallei, M. (2017):
Multi-stimuli responsive block copolymers as a smart release platform for a polypyridyl ruthenium complex.
In: Polymer Chemistry, The Royal Society of Chemistry, pp. 890-900, 8, DOI: 10.1039/C6PY02026G, [Online-Edition: http://dx.doi.org/10.1039/C6PY02026G],
[Article]

Abstract

A variety of applications of amphiphilic block copolymers result from the control of their self-assembled structures. Herein, the synthesis and structure formation of block copolymers (BCPs) consisting of poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) as one segment and poly(methyl methacrylate) (PMMA) or a statistical copolymer (PDMAEMA-co-PMMA) as a second segment, is described. The BCPs provide molar masses between 8.9 kg mol-1 and 35.6 kg mol-1 with low polydispersity index values, D = 1.05-1.13. BCPs are synthesized via sequential anionic polymerization strategies while structure formation in water is investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The PDMAEMA-containing micelles in water are loaded with a Ru(ii) polypyridyl complex, i.e. Ru(bipy)2-dppz-7-hydroxymethylPF62 (bipy = 2{,}2prime or minute-bipyridine; dppz = dipyridophenazine){,} which was previously shown to act as a potential photosensitizer in photodynamic therapy (PDT). Successful loading of the BCP micelles is evidenced by TEM measurements after dialysis in water. Stimulus-responsive release of the Ru(ii) complex from the BCP micelles is shown using ultrasound{,} change of pH or temperature as external triggers. The quantification and release profiles for the Ru(ii) complex are obtained by atomic absorption spectrometry (AAS). As a result{,} PDMAEMA-b-PMMA is not capable of releasing the Ru(ii) complex in a controlled manner after application of{,} for instance{,} ultrasound or temperature change as external triggers due to the shielding (stealth effect) of the BCP. On the contrary{,} micelles made of BCPs featuring PDMAEMA and PDMAEMA-co-PMMA segments reveal excellent Ru(ii) complex release profiles due to the tailored molecular composition of the underlying block segments as evidenced by temperature-dependent DLS and AAS measurements. Thus{,} these smart PDMAEMA-containing BCPs pave the way to a variety of applications for selective triggered release of small molecules.

Item Type: Article
Erschienen: 2017
Creators: Appold, M. and Mari, C. and Lederle, C. and Elbert, J. and Schmidt, C. and Ott, I. and Stühn, B. and Gasser, G. and Gallei, M.
Title: Multi-stimuli responsive block copolymers as a smart release platform for a polypyridyl ruthenium complex
Language: English
Abstract:

A variety of applications of amphiphilic block copolymers result from the control of their self-assembled structures. Herein, the synthesis and structure formation of block copolymers (BCPs) consisting of poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) as one segment and poly(methyl methacrylate) (PMMA) or a statistical copolymer (PDMAEMA-co-PMMA) as a second segment, is described. The BCPs provide molar masses between 8.9 kg mol-1 and 35.6 kg mol-1 with low polydispersity index values, D = 1.05-1.13. BCPs are synthesized via sequential anionic polymerization strategies while structure formation in water is investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The PDMAEMA-containing micelles in water are loaded with a Ru(ii) polypyridyl complex, i.e. Ru(bipy)2-dppz-7-hydroxymethylPF62 (bipy = 2{,}2prime or minute-bipyridine; dppz = dipyridophenazine){,} which was previously shown to act as a potential photosensitizer in photodynamic therapy (PDT). Successful loading of the BCP micelles is evidenced by TEM measurements after dialysis in water. Stimulus-responsive release of the Ru(ii) complex from the BCP micelles is shown using ultrasound{,} change of pH or temperature as external triggers. The quantification and release profiles for the Ru(ii) complex are obtained by atomic absorption spectrometry (AAS). As a result{,} PDMAEMA-b-PMMA is not capable of releasing the Ru(ii) complex in a controlled manner after application of{,} for instance{,} ultrasound or temperature change as external triggers due to the shielding (stealth effect) of the BCP. On the contrary{,} micelles made of BCPs featuring PDMAEMA and PDMAEMA-co-PMMA segments reveal excellent Ru(ii) complex release profiles due to the tailored molecular composition of the underlying block segments as evidenced by temperature-dependent DLS and AAS measurements. Thus{,} these smart PDMAEMA-containing BCPs pave the way to a variety of applications for selective triggered release of small molecules.

Journal or Publication Title: Polymer Chemistry
Volume: 8
Publisher: The Royal Society of Chemistry
Divisions: 05 Department of Physics > Institute for condensed matter physics > Experimental Condensed Matter Physics
05 Department of Physics > Institute for condensed matter physics
05 Department of Physics
Date Deposited: 21 Nov 2017 09:03
DOI: 10.1039/C6PY02026G
Official URL: http://dx.doi.org/10.1039/C6PY02026G
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