Ultrafast molecular rotor: an efficient sensor for premelting of natural DNA

Abstract

Structural changes in nucleic acids in the premelting region (T < melting temperature, T(m)) play an important role in the biological activity of DNA at physiological temperature. In the present communication we report the use of an ultrafast molecular rotor as an extrinsic fluorescence sensor to monitor the structural changes in natural DNA at T < T(m), which could not be detected even by circular dichroism spectroscopy. Further, the fluorescence sensor used in the present study is superior than most commonly used DNA stains.

An Ultrafast Molecular‐Rotor‐Based Fluorescent Turn‐On Sensor for the Perrhenate Anion in Aqueous Solution

“…However, ThT displays a significantly enhanced emission in viscous solvents, and in a wide variety of confined environments, in which the torsional relaxation of ThT is impeded . By utilizing this feature, monomeric ThT has been used as a turn‐on probe for a few important biological and chemical assemblies, such as amyloid fibrils, hydrocarbon chains in ternary complexation with γ‐cyclodextrin, microviscosity at the interface of reverse micelles, and minute structural changes in DNA …”

Thioflavin T: A versatile optical probe for chemo and biosensing

“…ThT has been identified as an amyloid fibril sensor for last 50 years, but now, it has recently been in focus for its interaction with nucleic acids/DNA (Ilanchelian and Ramaraj, 2004;Liu et al, 2013). ThT, upon interacting with DNA, displays a dramatic fluorescence enhancement, compared to other DNA binding dyes like ethidium bromide and 4'6diaminodino-2 phenylindole (Murudkar et al, 2012). The increase in fluorescence intensity of ThT, on association with DNA, is attributed to restriction of its intramolecular torsional relaxation.…”

“…The increase in fluorescence intensity of ThT, on association with DNA, is attributed to restriction of its intramolecular torsional relaxation. On binding to DNA, the ultrafast bond twisting process around central C-C bond in ThT, is suppressed and as a result the non-radiative deactivation channel is set off and fluorescence is switched on (Ilanchelian and Ramaraj, 2004;Murudkar et al, 2012). This remarkable increase in fluorescence intensity of ThT on binding to DNA led to tremendous research activity in constructing sensor platforms based on ThT for detection of different types of DNA.…”

“…ThT-DNA interaction has been exploited in various formats to construct sensors for secondary structural change in DNA or DNA structures implicated in disease conditions. One such study is employing ThT as sensor for studying premelting structural changes in DNA, wherein ThT was found to be sensitive to structural changes induced by temperature, in pre-melting regime, which remains undetected by other spectroscopic techniques like Circular Dichroism spectroscopy (Murudkar et al, 2012). Another interesting work, wherein ThT acts as a fluorescent probe to understand the interaction between imidazolium based ionic liquids and calf thymus DNA was reported in 2012 .…”

“…restricted micro-environment, the non-radiative ultrafast bond twisting process is suppressed, as a consequence of which, ThT exhibits fluorescence enhancement by several orders of magnitudes (Singh et al, 2010a;Singh et al, 2010b). This characteristic increase in fluorescence intensity of ThT forms the basis of its sensory mechanism for wide array of analytes like amyloid fibrils, DNA (Murudkar et al, 2012), heparin (Mudliar and Singh, 2016a), metal-ions (Ge et al, 2014;Wang et al, 2011) and so on.…”