Fluorescent DNA probes at liquid/liquid interfaces studied by surface second harmonic generation

Abstract

The properties of a series of oxazole yellow dyes, including the dicationic YOPRO-1 and its homodimeric parent YOYO-1 and two monocationic dyes (YOSAC-1 and YOSAC-3), have been investigated at the dodecane/water interface using stationary and time-resolved surface second harmonic generation (SSHG) combined with quantum chemical calculations. Whereas YOYO-1 exists predominantly as a H-dimer in aqueous solution, the stationary SSHG spectra reveal that such dimers are not formed at the interface. No significant H-aggregation was observed with YOPRO-1, neither in solution nor at the interface. In the case of the monocationic YOSAC dyes, a distinct SSHG band due to H-aggregates was measured at the interface, whereas only weak aggregation was found in solution. These distinct aggregation behaviors can be explained by the different orientations of the dyes at the interface, as revealed from the analysis of polarization-resolved experiments, the doubly-charged dyes lying more flat on the interface than the singly charged ones. Although YOYO-1 and YOPRO-1 do not form H-dimer/aggregates at the interface, time-resolved SSHG measurements point to the occurrence of intra- and intermolecular interactions, respectively, which inhibit the ultrafast non-radiative decay of the excited dyes via large amplitude motion, and lead to a nanosecond excited-state lifetime. The distinct behavior evidenced here for YOYO-1 and YOSAC dyes points to their potential use as fluorescent or SHG interfacial probes.

Spatially Dependent Fluorescent Probe for Detecting Different Situations of Mitochondrial Membrane Potential Conveniently and Efficiently

“…In order to attain the objective, it should be rational to design such a probe based on organic cationic compounds (OCCs), because some OCCs can accumulate in mitochondria with normal MMP. − On the other hand, some other OCCs just locate in the nucleus due to its static interaction with DNA as well as the inserted layer effect with DNA grooves. , Thus, we believe that, by balancing the interaction of OCC between MMP and DNA to finely control its targeting ability, a spatially dependent probe can be obtained which meets the requirements above, but it is still challenging. Previously, our group has reported two OCCs probes: CAI and 9E-BMVC .…”

Ionic hydration-induced evolution of decane–water interfacial tension

“…Khanamiri et al 24 demonstrated that Ca 2+ is conductive to lower IFT and changes the oil-water interfacial elastic modulus. Some technologies have been proposed to investigate the oil-water interface, such as surface second harmonic generation, 25 small-angle neutron scattering 26 and vibrational sum-frequency spectroscopy, 27 but the dynamics of ions or molecules near the interface are not fully addressed. The molecular dynamics (MD) method which can be used to obtain the detailed microscopic structures is a powerful tool to investigate the macroscopic properties of the oil-water interface with the applicability of the statistical mechanics.…”

Template‐Free Self‐Assembly of Dimeric Dicarbocyanine Dyes

“…Interestingly, the enhancement in fluorescence upon addition of 6 was significantly greater in the presence of a fixed amount of 5 a than without (see Figure ). In this regard, H‐dimers of oxazole‐based cyanine dyes YO and YOYO have been shown to exhibit weak fluorescence ,. Enhancement of YO and YOYO fluorescence upon DNA binding has been suggested to arise due to a combination of the inhibition of dye isomerization as well as disruption of H‐dimers ,.…”