The development of a water-soluble, perylenemonoimide (PMI) dye-doped polymer nanoparticle (PNP) with NIR emission for live-cell imaging is demonstrated. The large Stokes-shifted NIR emission is due to confined nanospace-induced aggregation offered by the polymer matrix. Later, folic acid functionalised PNP (PNP-FA) is successfully employed to differentiate folate receptor positive and negative cancer cells.
SummaryOne important access to monodisperse (functionalized) oligoPPEs is based on the orthogonality of the alkyne protecting groups triisopropylsilyl and hydroxymethyl (HOM) and on the polar tagging with the hydroxymethyl moiety for an easy chromatographic separation of the products. This paper provides an update of this synthetic route. For the deprotection of HOM protected alkynes, γ-MnO2 proved to be better than (highly) activated MnO2. The use of HOM as an alkyne protecting group is accompanied by carbometalation as a side reaction in the alkynyl–aryl coupling. The extent of carbometalation can be distinctly reduced through substitution of HOM for 1-hydroxyethyl. The strategy of polar tagging is extended by embedding ether linkages within the solubilising side chains. With building blocks such as 1,4-diiodo-2,5-bis(6-methoxyhexyl) less steps are needed to assemble oligoPPEs with functional end groups and the isolation of pure compounds becomes simple. For the preparation of 1,4-dialkyl-2,5-diiodobenzene a better procedure is presented together with the finding that 1,4-dialkyl-2,3-diiodobenzene, a constitutional isomer of 1,4-dialkyl-2,5-diiodobenzene, is one of the byproducts.
A series of peri‐functionalized perylenemonoimide dyes containing an electron donating aromatic and polyaromatic group via Suzuki‐coupling reaction has been synthesized. Photophysical properties of the synthesized dyes are extensively investigated using various spectroscopic techniques. Introduction of substituent's at peri‐position shows a pronounced effect on emission properties. Electrochemical measurements suggest that the peri‐functionalization of perylenemonoimide dyes make reduction much more facile compared to unsubstituted dyes. Thereafter, an efficient and selective fluorescence quenching strategy via photo‐induced electron transfer process from electron‐rich aromatic amines to the synthesized dyes has been investigated.
We show that oligo(phenyleneethynylene)s (oligoPEs) are ideal spacers for calibrating dye pairs used for Förster resonance energy transfer (FRET). Ensemble FRET measurements on linear and kinked diads with such spacers show the expected distance-and orientation-dependence of FRET. Measured FRET efficiencies match excellently with those predicted using a harmonic segmented chain model, which was validated by end-to-end distance distributions obtained from pulsed electron paramagnetic resonance measurements on spin-labeled oligoPEs with comparable label distances. Förster resonance energy transfer (FRET) 1,2 experiments exploit the distance-dependence of dipolar coupling between an electronically excited fluorescent dye, acting as energy donor, and a chromophore in its ground state, acting as energy acceptor. Since FRET provides a means for sensing inter-and intramolecular distances in the range of 30-100 Å, many FRET-based techniques have emerged, 3-9 e.g., in studies of protein folding and protein interaction. 10-13 Förster's theory 1 relates the FRET efficiency E with the inter-dye distance rda according to:
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