Details

Autor(en) / Beteiligte

• Vaz Serra, Vanda
• Neto, Nuno G. B
• Andrade, Suzana M
• Costa, Sílvia M. B

Titel

Core-Assisted Formation of Porphyrin J-Aggregates in pH-Sensitive Polyelectrolyte Microcapsules Followed by Fluorescence Lifetime Imaging Microscopy

Ist Teil von

• Langmuir, 2017-08, Vol.33 (31), p.7680-7691

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2017

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• A strategy assisted by an inorganic template was developed to promote the organized self-assembly of meso-(tetra­kis)-(p-sulfo­nato­phenyl)­porphyrin (TPPS) on pH-sensitive core–shell polyelectrolyte microcapsules (PECs) of poly­(styrene­sulfonate) (PSS) and poly­(allyl­amine hydro­chloride) (PAH). A key feature of this strategy is the use of template CaCO3 microparticles as a nucleation site endorsing inside–outside directional growth of porphyrin aggregates. Using this approach, TPPS self-assembly in positively charged PECs with CaCO3 (PAH/PSS)2PAH as a sequence of layers was successfully achieved using mild pH conditions (pH 3). Evidence for porphyrin aggregation was obtained by UV–vis with the characteristic absorption bands in PECs functionalized with porphyrins. Fluorescence lifetime imaging microscopy (FLIM) of the poly­electro­lyte core–shell confirmed the presence of radially distributed needlelike structures sticking out from polyelectrolyte shells. Microscopic images also revealed a sequential process (adsorption, redistribution, and aggregation) for the directional growth (inside/outside) of TPPS aggregates, which highlights the importance of the core in the aggregation induction. Removing the CaCO3 core alters the porphyrin interaction in the PEC environment, and aggregate growth is no longer favored.