Simple and sensitive fluorescence sensor for detection of potassium ion in the presence of high concentration of sodium ion using berberine–G-quadruplex complex as sensing element

G-Quadruplexes as Sensing Probes

“…Under optimal conditions, the colour change is visible to the naked eye within the concentration range from 2 to 1000 µM [30]. Another detection method for K + used G-quadruplex complex with berberine, the plant alkaloid with broad medical uses [31]. After addition of K + single stranded DNA folded into G-quadruplex and after incubation with berberine formation of berberine-G-quadruplex complex occurred leading to a marked increase in fluorescent signal.…”

“…After addition of K + single stranded DNA folded into G-quadruplex and after incubation with berberine formation of berberine-G-quadruplex complex occurred leading to a marked increase in fluorescent signal. In the presence of 800 mM of Na + ions fluorescence of the berberine-G-quadruplex was linearly increasing with an increasing concentration of K + within the range from 0.005 to 1.0 mM [31].…”

Turn-on and label-free fluorescence detection of lead ions based on target-induced G-quadruplex formation

“…Just like NMM, both of them exhibit a strong increase in fluorescence upon binding to certain G-quadruplex structures. [41][42][43] Surprisingly, by utilizing G3T4 and G3T4TT4 as sensing elements individually, we found that both ThT and berberine exhibited significant fluorescence enhancement in the presence of Pb 2+ (for example, by using G3T4 as the sensing element, the fluorescence intensity of ThT at 480 nm increased ca. 27-fold in the presence of 1 mM Pb 2+ ).…”

“…19 Here, the turn-on readout demonstrates that, for these sequences, the more compact G-quadruplexes stabilized by Pb 2+ have strong binding affinity with ThT, berberine and NMM, respectively, resulting from the fit interaction of fluorescent ligands with the conformation of targetinduced G-quadruplexes. 32,42,43 Further experiments are in progress to study the mechanism of the interaction of fluorescent ligands with Pb 2+ -induced G-quadruplexes.…”

Metal ion induced fluorescence resonance energy transfer between crown ether functionalized quantum dots and rhodamine B: selectivity of K+ ion

“…The determined value for K + ion was found to be lower than those reported previously, 17a,18e,26,27 and close to some earlier literatures. 17b, 21,28,29 Note that the sensing of K + ion by using colorimetric methods exhibited lower detection limit in the nM range. 30,31…”