Abstract:The ultrafast photochemistry of a new spiropyran photoswitch (Py-BIPS) has been investigated, revealing many advantages in the application in water over the previously studied spiropyrans. Functionalized Py-BIPS derivatives are presented for the study of pH dependence, stability, toxicity, and the thermal and photochemical behavior on longer time scales in aqueous media using several spectroscopic methods. These investigations pave the way for the practical use of Py-BIPS derivatives as photoswitchable ligands… Show more
“…Repeated photoswitching cycles did not significantly alter the initially observed switching characteristics. Additionally, photoswitching was also not associated with significant photobleaching, consistent with previous reports on other spiropyran compounds 21, 22 .Figure 4UV dependent photoswitching of N -nitroBIPS-DPPG fluorescence. The fluorescence (λex = 543 nm, λem = 600 nm) of a DOPC/ N -nitroBIPS-DPPG (9:1) dispersion (50 μM) was recorded during alternating (5 sec intervals) UV (340 nm) and green light (543 nm) exposure (red line) and during continuous green light (543 nm) irradiation (blue line).…”
We have developed and characterized a novel photoswitchable phospholipid analog termed N-nitroBIPS-DPPG. The fluorescence can be switched on and off repeatedly with minimal photobleaching by UV or visible light exposure, respectively. The rather large photochromic head group is inserted deeply into the interfacial membrane region conferring a conical overall lipid shape, preference for a positive curvature and only minimal intermembrane transfer. Utilizing the switchable NBD fluorescence quenching ability of N-nitroBIPS-DPPG, a detergent free intermembrane transfer assay system for NBD modified lipids was demonstrated and validated. As NBD quenching can be turned off, total NBD associated sample fluorescence can be determined without the need of detergents. This not only reduces detergent associated systematic errors, but also simplifies assay handling and allows assay extension to detergent insoluble lipid species.
“…Repeated photoswitching cycles did not significantly alter the initially observed switching characteristics. Additionally, photoswitching was also not associated with significant photobleaching, consistent with previous reports on other spiropyran compounds 21, 22 .Figure 4UV dependent photoswitching of N -nitroBIPS-DPPG fluorescence. The fluorescence (λex = 543 nm, λem = 600 nm) of a DOPC/ N -nitroBIPS-DPPG (9:1) dispersion (50 μM) was recorded during alternating (5 sec intervals) UV (340 nm) and green light (543 nm) exposure (red line) and during continuous green light (543 nm) irradiation (blue line).…”
We have developed and characterized a novel photoswitchable phospholipid analog termed N-nitroBIPS-DPPG. The fluorescence can be switched on and off repeatedly with minimal photobleaching by UV or visible light exposure, respectively. The rather large photochromic head group is inserted deeply into the interfacial membrane region conferring a conical overall lipid shape, preference for a positive curvature and only minimal intermembrane transfer. Utilizing the switchable NBD fluorescence quenching ability of N-nitroBIPS-DPPG, a detergent free intermembrane transfer assay system for NBD modified lipids was demonstrated and validated. As NBD quenching can be turned off, total NBD associated sample fluorescence can be determined without the need of detergents. This not only reduces detergent associated systematic errors, but also simplifies assay handling and allows assay extension to detergent insoluble lipid species.
“…[3][4][5][6][7][8] However, most photochromic compounds have low solubility and stability in water and thus their application is restricted to non-aqueous environments. To date, there is a limited number of studies of photoswitches in aqueous solutions, [9][10][11][12][13][14][15][16][17] of which only a few are focused on the investigation of the ultrafast photochemical reactions (e.g. spiropyran 13 and azobenzene 18 ).…”
Photochromic switches are essential for the control and manipulation of nanoscale reactions and processes. The expansion of their application to aqueous environments depends strongly on the development of optimized water-soluble photoswitches. Here we present a femtosecond time-resolved investigation of the photochromic reactions (transition between the open and the closed form) of a water-soluble indolylfulgimide. We observe a pronounced effect of the protic nature of water as a solvent on the ultrafast ring-opening reaction. Typically, the excited state of the closed form has a larger dipole moment than the ground state, which leads to stabilization of the excited state in polar solvents and hence a lifetime (3 ps) longer than in non-polar solvents (2 ps). However, in water, despite the increased solvent polarity and the increased excited state dipole moment, the opposite trend for the excited state lifetime is observed (1.8 ps). This effect is caused by the opening of a new excited state deactivation pathway involving proton transfer reactions.
“…The other approach uses reversible photoswitches that can exist in two stable states. Azobenzenes,21–23 spiropyrans,24–28 diarylethenes,29–33 fulgide,34–36 fulgimide,37, 38 hemithioindigos,39–41 and overcrowded alkenes42, 43 are prominent switches, and most of these switches have already been applied to the regulation of nucleic acids. For the light control of nucleic acids, the photoswitch itself and the linker that connects the photoswitch to the oligonucleotide are very important for an effective regulation event.…”
Herein, we report the reversible light-regulated destabilization of DNA duplexes by using azobenzene C-nucleoside photoswitches. The incorporation of two different azobenzene residues into DNA and their photoswitching properties are described. These new residues demonstrate a photoinduced destabilization effect comparable to the widely applied D-threoninol-linked azobenzene switch, which is currently the benchmark. The photoswitches presented herein show excellent photoswitching efficiencies in DNA duplexes - even at room temperature - which are superior to commonly used azobenzene-based nucleic acid photoswitches. In addition, these photoswitching residues exhibit high thermal stability and excellent fatigue resistance, thus rendering them one of the most efficient candidates for the regulation of duplex stability with light.
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