Photophysics of New Water‐Soluble Terrylenediimide Derivatives and Applications in Biology

Abstract

The photophysical properties of three new water-soluble terrylenediimide (WS-TDI) derivatives are investigated and their utilization in biological experiments is demonstrated. Each of these dyes can be excited in the far red region of the visible spectrum, making them good candidates for in-vivo studies. Single-molecule techniques characterize their photophysics that is, the number of emitted photons, blinking characteristics and survival times until photobleaching takes place. All three dyes exhibit bright fluorescence, as well as an extremely high resistance against photodegradation compared to other well-known fluorophores. Due to their different characteristics the three new WS-TDI derivatives are suitable for specialized biological applications. WS-TDI dodecyl forms non-fluorescent aggregates in water which can be disrupted in a hydrophobic environment leading to a monomeric fluorescent form. Due to its high lipophilicity WS-TDI dodecyl anchors efficiently in lipid bilayers with its alkyl chain and hence can be ideally used to image membranes and membrane-containing compartments in living cells. In contrast, the positively charged WS-TDI pyridoxy is a new type of chromophore in the WS-TDI family. It is fully solubilized in water forming fluorescent monomers and is successfully used to label the envelope of herpes simplex viruses. Finally, it is shown that a WS-TDI derivative functionalized with N-hydroxysuccinimide ester moiety (WS-TDI/NHS ester) provides a versatile reactive dye molecule for the specific labelling of amino groups in biomolecules such as DNA.

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“…7,16 As to optical detection, Christoph Bräuchle and Thomas Basché have shown terrylene diimide (TDI, 1b) to be an ideal chromophore for SMS due to its high 21 fluorescence quantum yield and its emission above 700 nm, which made it applicable as a tracking molecule for biological studies. 7,[17][18][19] The main advantage of TDI (1b) and its analogues over other dyes, some of which may be commercially available, is their extremely high photostability. This property also proved to be advantageous for the case of dibenzo-fused QDI, which has a bathochromically shifted emission spectrum.…”

Single Molecule Microscopy

“…liquid-crystal displays, laser, solar-energy converters or bioimaging. For the latter application, fluorescence microscopy has been one of the most popular and powerful tools in the last years [13,14,[33][34][35][36][37][38][39][40][41][42][43][44].…”

“…Hence, SMS has become a common method to study the dynamical behavior of labeled proteins, virions, drugs, and other bioparticles [13,[41][42][43][44]. Since most of the bioprocesses are studied in water or buffer solutions, the interest in new water-soluble fluorescent dyes for labeling biosystems increased over the last few years continuously [33,34,45].…”

“…However, for SMS measurements it is important to have dyes with a high photostability in order to collect a large amount of information during the experiment. In addition, such dyes should absorb and fluoresce above 600 nm to reduce the background from the autofluorescence of living cells [33,34,45].…”

“…However, most of them are not soluble in water [33,34]. This problem can be tackled by specific functionalization of the rylene scaffold.…”