Svechkarev D, Kyrychenko A, Payne WM
… +1 more, Mohs AM
J Photochem Photobiol A Chem
· 2018 Feb · PMID 29430162
·
Full text
Fluorescent nanomaterials require high colloidal stability for effective use in imaging and sensing applications. We herein report the synthesis of carbazole-based organic fluorescent nanoaggregates, and demonstrate the...Fluorescent nanomaterials require high colloidal stability for effective use in imaging and sensing applications. We herein report the synthesis of carbazole-based organic fluorescent nanoaggregates, and demonstrate the superior colloidal stability of alkyl-substituted dye aggregates over their non-alkylated analogs. The role of alkyl chains in self-assembly and stability of such nanoaggregates is discussed based on both experimental and molecular dynamics simulation data, and spectral characteristics of the precursor dyes and their aggregates are described. The obtained results provide new insights on development of colloidally stable organic fluorescent nanomaterials with low polydispersity.
J Photochem Photobiol A Chem
· 2016 Oct · PMID 29249888
·
Full text
Intramolecular cycloadditions of aza-o-xylylenes generated via excited state intramolecular proton transfer (ESIPT) to furanacetic acid-based unsaturated pendants was shown to overcome the unfavorable energetics of the a...Intramolecular cycloadditions of aza-o-xylylenes generated via excited state intramolecular proton transfer (ESIPT) to furanacetic acid-based unsaturated pendants was shown to overcome the unfavorable energetics of the azetidinone ring formation, offering rapid access to β-lactams as primary photoproducts. These 2,3- and 3,4-dihydrofuran-containing reactive intermediates are suitable for a broad spectrum of postphotochemical transformations yielding complex polyheterocyclic molecular architectures possessing the β-lactam moiety.
Siclovan TM, Zhang R, Cotero V
… +6 more, Bajaj A, Dylov DV, Yazdanfar S, Carter R, Tan Hehir CA, Natarajan A
J Photochem Photobiol A Chem
· 2016 Feb · PMID 26693208
·
Full text
Several classes of diversely substituted styryl type dyes have been synthesized with the goal of extending their expected fluorescent properties as much towards red as possible given the constraint that they maintain dru...Several classes of diversely substituted styryl type dyes have been synthesized with the goal of extending their expected fluorescent properties as much towards red as possible given the constraint that they maintain drug-like properties and retain high affinity binding to their biological target. We report on the synthesis, optical properties of a series of styryl dyes ( ), and the anomalous photophysical behavior of several of these Donor-Acceptor pairs separated by long conjugated π-systems ( ). We further describe an unusual dual emission behavior with two distinct ground state conformers which could be individually excited to locally excited (LE) and twisted intramolecular charge transfer (TICT) excited state in push-pull dye systems ( , and ). Additionally, unexpected emission behavior in dye systems and wherein the amino- derivative displayed a dual emission in polar medium while the N,N-dimethyl derivative and other methylated derivatives showed only LE emission but did not show any TICT emission. Based on photophysical and nerve binding studies, we down selected compounds that exhibited the most robust fluorescent staining of nerve tissue sections. These dyes ( , , and ) were subsequently selected for fluorescence imaging studies in rodents using the small animal multispectral imaging instrument and the dual-mode laparoscopic instrument developed in-house.
J Photochem Photobiol A Chem
· 2015 Oct · PMID 26190906
·
Full text
This article reviews the zinc(II)-dependent photophysical properties of arylvinylbipyridines (AVBs), a class of fluoroionophores in which 2,2'-bipyridyl and an aryl moiety are electronically conjugated. Zinc(II) binding...This article reviews the zinc(II)-dependent photophysical properties of arylvinylbipyridines (AVBs), a class of fluoroionophores in which 2,2'-bipyridyl and an aryl moiety are electronically conjugated. Zinc(II) binding of an AVB may lead to an emission bathochromic shift of the fluoroionophore without diminishing its fluorescence quantum yield. This observation can be explained using the excited state model of electron donor-π bridge-electron acceptor "push-pull" fluorophores, in which the bipy moiety acts as an electron acceptor, and zinc(II)-coordination strengthens its electron affinity. The spectral sensitivity of bipy-containing fluoroionophores, such as AVBs, to zinc(II) can be exploited to prepare fluorescent indicators for this ion. In several cases, AVB moieties are incorporated in fluorescent heteroditopic ligands, so that the variation of zinc(II) concentration over a relatively large range can be correlated to fluorescence changes in either intensity or color. AVB fluoroionophores are also used to introduce an intramolecular Förster resonance energy transfer (FRET) strategy for creating zinc(II) indicators with high photostability and a narrow emission band, two desired characteristics of dyes used in fluorescence microscopy.
Ezhov RN, Metzel GA, Mukhina OA
… +4 more, Musselman CA, Kutateladze TG, Gustafson TP, Kutateladze AG
J Photochem Photobiol A Chem
· 2014 Sep · PMID 25197204
·
Full text
A new strategy for encoding polypeptide libraries with photolabile tags is developed. The photoassisted assay, based on conditional release of encoding tags only from bound pairs, can differentiate between peptides which...A new strategy for encoding polypeptide libraries with photolabile tags is developed. The photoassisted assay, based on conditional release of encoding tags only from bound pairs, can differentiate between peptides which have minor differences in a form of post-translational modifications with epigenetic marks. The encoding strategy is fully compatible with automated peptide synthesis. The encoding pendants are compact and do not perturb potential binding interactions.
J Photochem Photobiol A Chem
· 2013 Mar · PMID 23833546
·
Full text
Lanthanide ions luminescence has long life time enabling highly sensitive detection in time-gated mode. The synthesis of reactive lanthanide probes for covalent labeling of the objects of interest is cumbersome task due...Lanthanide ions luminescence has long life time enabling highly sensitive detection in time-gated mode. The synthesis of reactive lanthanide probes for covalent labeling of the objects of interest is cumbersome task due to the large size of the probes, complex multi-step procedures and the presence of sensitive groups, which often prevents introduction of reactive cross-linking functions optimal for conjugation. We suggest simple synthetic protocol for luminescent europium chelates based on serendipitous reaction yielding acylating compounds, whose reactivity is comparable to that of commonly used N-hydroxysuccinimide (NHS) esters. The probes react with proteins at pH 7.0 within several minutes at ambient temperature displaying high coupling efficiency. The resulting conjugates survive electrophoretic separation under denaturing conditions, which makes the labels useful in proteomic studies that rely on high detection sensitivity.
J Photochem Photobiol A Chem
· 2013 Feb · PMID 23833545
·
Full text
Luminescent lanthanide ion complexes are distinguished by unique light emitting properties that enable both highly sensitive detection of lanthanide labels attached to biomolecules and contrast imaging of various micro o...Luminescent lanthanide ion complexes are distinguished by unique light emitting properties that enable both highly sensitive detection of lanthanide labels attached to biomolecules and contrast imaging of various micro objects (cells, nanoparticles, etc.). Previously, we synthesized amine-reactive cs124-based luminescent lanthanide chelates with improved brightness and metal retention. Here we report the synthesis of new thiol-reactive derivatives of the same compounds including bromoacetamido-, and maleimido- forms of cs124 and cs124CF fluorophores. Maleimido-compounds displayed exceptional reactivity instantaneously coupling to thiols at physiological conditions at micromolar probes concentrations. Surprisingly, they displayed strong quenching by adjacent maleimido-group, which was completely eliminated after reaction with thiols, thereby enabling their simple detection by monitoring the light emission of the reaction mixture. This reaction can be used for hyper-sensitive determination of biologically important sulphydryl compounds (e.g. glutathione, co-enzyme A, etc.) in time-resolved mode.
J Photochem Photobiol A Chem
· 2012 Nov · PMID 24926175
·
Full text
Energy transfer between a CdSe/ZnS nanocrystal (NC) donor and a rhodamine isothiocyanate (RITC) acceptor has been achieved via a functionalized poly(acrylic acid) (PAA) encapsulating layer over the surface of the NC. The...Energy transfer between a CdSe/ZnS nanocrystal (NC) donor and a rhodamine isothiocyanate (RITC) acceptor has been achieved via a functionalized poly(acrylic acid) (PAA) encapsulating layer over the surface of the NC. The modification of PAA with both -octylamine (OA) and 5-amino-1-pentanol (AP), [PAA-OA-AP], allows for the simultaneous water-solubilization and functionalization of the NCs, underscoring the ease of synthesizing NC-acceptor conjugates with this strategy. Photophysical studies of the NC-RITC constructs showed that energy transfer is efficient, with approaching 10 s. The ease of the covalent conjugation of molecules to NCs with PAA-OA-AP coating, together with efficient energy transfer, makes the NCs encapsulated with PAA-OA-AP attractive candidates for sensing applications.
J Photochem Photobiol A Chem
· 2012 Jun · PMID 22754267
·
Full text
The syntheses and photophysical properties of 1-(5-methylhexyl)-2,3,7,8-tetrahydro-1H-naphtho[2,1-e]indol-9(6H)-one (7a) and 1-(5-methylhexyl)-2,3,8,9-tetrahydro-1H-naphtho[2,1-e]indol-6(7H)-one (7b) are reported. They a...The syntheses and photophysical properties of 1-(5-methylhexyl)-2,3,7,8-tetrahydro-1H-naphtho[2,1-e]indol-9(6H)-one (7a) and 1-(5-methylhexyl)-2,3,8,9-tetrahydro-1H-naphtho[2,1-e]indol-6(7H)-one (7b) are reported. They are prepared in eight steps from the corresponding bromonaphthylamines. These fluorescent compounds have PRODAN-like cores, and they are structurally similar to cholesterol. Compound 7a is the first reported PRODAN derivative where both the amino and carbonyl groups are constrained to be coplanar with the naphthalene core. Comparing the photophysical behavior of these compounds with related compounds indicates that locking the amino group in a five-membered ring enhances their desirable properties as solvent polarity sensors.
Tucker MJ, Abdo M, Courter JR
… +3 more, Chen J, Smith AB, Hochstrasser RM
J Photochem Photobiol A Chem
· 2012 Apr · PMID 22577259
·
Full text
The tetrazine chromophore holds promise as an effective photochemical trigger to achieve structural release, directed at the determination of peptide/protein motions that occur early in the folding processes. The photoch...The tetrazine chromophore holds promise as an effective photochemical trigger to achieve structural release, directed at the determination of peptide/protein motions that occur early in the folding processes. The photochemistry of 3,6-di-cysteine-S,S-tetrazines was examined by femtosecond IR transient absorption spectroscopy. Excitation of the tetrazine chromophore by visible and near UV light in the end yields chemically inert, structurally unobtrusive photoproducts that are not expected to interfere with the conformational dynamics of peptides and proteins. Dicysteine S,S-tetrazine is suggested to undergo photocleavage via a photochemical pathway different than the parent molecule s-tetrazine, based on kinetic measurements that reveal a stepwise reaction pathway of photofragmentation, whereby the initial ring cleavage event occurs prior to the formation of the SCN groups.
J Photochem Photobiol A Chem
· 2012 May · PMID 22563206
·
Full text
Relative rates of the photosensitized production of singlet oxygen ((1)O(2)) and of superoxide (O(2) (•-)) were determined using different couples of dyes and sacrificial electron donors (SEDs) of either high or low hydr...Relative rates of the photosensitized production of singlet oxygen ((1)O(2)) and of superoxide (O(2) (•-)) were determined using different couples of dyes and sacrificial electron donors (SEDs) of either high or low hydrophobicities. Such rates were also measured in the absence and presence of single unilamellar vesicles (SUVs) with 9DMPC:1DMPA mol ratio composition. The dyes aluminum phthalocyanine tetrasulfonate (AlPcS(4)) and pheophorbide-a (PHEO) were used as hydrophilic and hydrophobic photosensitizers, respectively. Xanthine (X) and glutathione (GSH) were used as hydrophobic and hydrophilic SEDs, respectively. The presence of SUVs in the aqueous sample produces the physical separation or encounter of SEDs and photosensitizers according to their membrane binding constants. When both the SED and the photosensitizer are localized within the same phase, a strong decrease in the rate of (1)O(2) formation, united to a strong increase in the rate of O(2) (•-) formation, is observed, relative to when both of these species are localized in different phases. The lipid phase is always present in the biological milieu. Thus, the use of a hydrophobic couple of both dye and SED (as in the case of X and PHEO), as well as a hydrophilic couple of both dye and SED (as in the case of GSH and AlPcS4), should strongly favor the Type I mechanism over the Type II. Since only a small number of hydroxyl radicals are needed to initiate a chain reaction of phospholipid peroxidation, the latter could be more toxic to the tumor tissue than peroxidation by a much higher concentration of singlet oxygen molecules.
Zhang Y, Barnes AN, Zhu X
… +2 more, Campbell NF, Gao R
J Photochem Photobiol A Chem
· 2011 Oct · PMID 22081749
·
Full text
Thiopurines were examined for their ability to produce singlet oxygen ((1)O(2)) with UVA light. The target compounds were three thiopurine prodrugs, azathioprine (Aza), 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG), a...Thiopurines were examined for their ability to produce singlet oxygen ((1)O(2)) with UVA light. The target compounds were three thiopurine prodrugs, azathioprine (Aza), 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG), and their S-methylated derivatives of 6-methylmercaptopurine (me6-MP) and 6-methylthioguanine (me6-TG). Our results showed that these thiopurines were efficient (1)O(2) sensitizers under UVA irradiation but rapidly lost their photoactivities for (1)O(2) production over time by a self-sensitized photooxidation of sulfur atoms in the presence of oxygen and UVA light. The initial quantum yields of (1)O(2) production were determined to be in the range of 0.30-0.6 in aqueous solutions. Substitution of a hydrogen atom with a nitroimidazole or methyl group at S decreased the efficacy of photosensitized (1)O(2) production as found for Aza, me6-MP and me6-TG. (1)O(2)-induced formation of 8-oxo-7,8-dihydro-2'-dexyguanosine (8-oxodGuo) was assessed by incubation of 6-methylthiopurine/UVA-treated calf thymus DNA with human repair enzyme 8-oxodGuo DNA glycosylase (hOGG1), followed by apurinic (AP) site determination. Because more 8-oxodGuo was formed in Tris D(2)O than in Tris H(2)O, (1)O(2) is implicated as a key species in the reaction. These findings provided quantitative information on the photosensitization efficacy of thiopurines and to some extent revealed the correlations between photoactivity and phototoxicity.
J Photochem Photobiol A Chem
· 2010 Feb · PMID 20473340
·
Full text
Phenyl substituted arsenic compounds are widely used as feed additives in the poultry industry and have become a serious environmental concern. We have demonstrated that phenylarsonic acid (PA) is readily degraded by TiO...Phenyl substituted arsenic compounds are widely used as feed additives in the poultry industry and have become a serious environmental concern. We have demonstrated that phenylarsonic acid (PA) is readily degraded by TiO(2) photocatalysis. Application of the Langmuir-Hinshelwood kinetic model for the initial stages of the TiO(2) photocatalysis of PA yields an apparent rate constant (k(r)) of 2.8 µmol/L·min and the pseudo-equilibrium constant (K) for PA is 34 L/mmol. The pH of the solution influences the adsorption and photocatalytic degradation of PA due to the surface charge of TiO(2) photocatalyst and speciation of PA. Phenol, catechol and hydroquinone are observed as the predominant products during the degradation. The roles of reactive oxygen species, •OH, (1)O(2), O(2) (-•) and h(VB) (+) were probed by adding appropriate scavengers to the reaction medium and the results suggest that •OH plays a major role in the degradation of PA. By-products studies indicate the surface of the catalyst plays a key role in the formation of the primary products and the subsequent oxidation pathways leading to the mineralization to inorganic arsenic. TiO(2) photocatalysis results in the rapid destruction of PA and may be attractive for the remediation of a variety of organoarsenic compounds.
J Photochem Photobiol A Chem
· 2009 Jan · PMID 20046228
·
Full text
Tamoxifen is a powerful drug used to treat breast cancer patients, and more than 500,000 women in the U. S. are being treated with this drug. In our study, tamoxifen is found to be photomutagenic in Salmonella typhimuriu...Tamoxifen is a powerful drug used to treat breast cancer patients, and more than 500,000 women in the U. S. are being treated with this drug. In our study, tamoxifen is found to be photomutagenic in Salmonella typhimurium TA102 at concentrations as low as 0.08 muM and reaches maximum photomutagenicity at 0.4 muM under a light dose equivalent to 20 min sunlight. These concentrations are comparable to the plasma tamoxifen concentration of 0.4 to 3 muM for patients undergoing tamoxifen therapy. The toxicity seems to be the result of DNA damage and/or lipid peroxidation caused by light irradiation of tamoxifen. The DNA damage caused by irradiation of PhiX174 DNA in the presence of tamoxifen appears to be formation of DNA-tamoxifen covalent adducts, not single strand/double strand cleavages, and there is no oxygen involvement. This is confirmed by EPR experiments that carbon-centerd radicals are formed by light irradiation of tamoxifen and there is no singlet oxygen formation. Although superoxide radical is formed, it is not involved in DNA damage.
Lee H, Berezin MY, Henary M
… +2 more, Strekowski L, Achilefu S
J Photochem Photobiol A Chem
· 2008 Dec · PMID 20016664
·
Full text
Structurally diverse near-infrared (NIR) absorbing polymethine dyes were prepared and their fluorescence lifetimes (FLT) were evaluated in relation to their structural features. Comparative FLT analysis based on the modi...Structurally diverse near-infrared (NIR) absorbing polymethine dyes were prepared and their fluorescence lifetimes (FLT) were evaluated in relation to their structural features. Comparative FLT analysis based on the modification of methine chain length and heterocyclic system showed that indolium or benz[e]indolium heptamethine dyes exhibited longer FLT than the benz[c,d]indolium trimethine dye. Modification of heterocyclic system alone with an intact chain length showed that indolium-based heptamethine dyes showed approximately 30% longer FLT than the benz[e]indolium-based dyes. In general, the FLT of polymethine dyes increased from polar to non-polar solvents. In addition, correlation study between the theoretical and the experimental FLT for indocyanine green (ICG) suggests that the lack of structural rigidity for these cyanine dyes is primarily responsible for the loss of the excited state energy via non-radiative pathway.
J Photochem Photobiol A Chem
· 2009 Aug · PMID 19946642
·
Full text
For a series of rhodamine dyes, two-photon absorption (TPA) and two-photon fluorescence (TPF) have been performed in different solvents. Solvent-dependent TPA spectra of these dyes were measured with open aperture z-scan...For a series of rhodamine dyes, two-photon absorption (TPA) and two-photon fluorescence (TPF) have been performed in different solvents. Solvent-dependent TPA spectra of these dyes were measured with open aperture z-scan method and compared to their respective single-photon spectra at equivalent energies. In the TPA spectra, relative peak intensities and positions are highly solvent dependent, which could be a result of vibronic couplings that depend on solvent environment. Measured TPA cross-sections of rhodamine dyes are consistently higher in nonpolar solvents. Certain complementary and similarity between TPA and TPF are also elucidated. Finally, a two-photon figure-of-merit is presented for these dyes in different solvents as a function of wavelength.
Islamova NI, Chen X, Digirolamo JA
… +2 more, Silva Y, Lees WJ
J Photochem Photobiol A Chem
· 2008 Sep · PMID 19727432
·
Full text
The photochromic properties and thermal stability of a newly synthesized fluorinated N-ethoxycarbonylmethyl indolylfulgimide substituted on the imide nitrogen were examined in a protic and aprotic environment. The absorp...The photochromic properties and thermal stability of a newly synthesized fluorinated N-ethoxycarbonylmethyl indolylfulgimide substituted on the imide nitrogen were examined in a protic and aprotic environment. The absorption spectra and extinction coefficients of the Z- and C-forms of the fluorinated indolylfulgimide (open and closed, respectively) were measured in a binary 70/30 ethanol/water system and in toluene. The results demonstrated a favorable bathochromic shift of the absorption maxima for both the open and closed forms of the fulgimide when the solvent was changed from aprotic toluene to protic aqueous ethanol. In addition, the photochemical stability of the new fulgimide was found to be high (0.056% and 0.020% degradation each time the fulgimide is cycled between the open and closed form in 70/30 ethanol/water and in toluene, respectively). The thermal stability of both forms of the fulgimide in 70/30 ethanol/water at 50 degrees C, toluene at 80 degrees C, and polymer film (PMMA) at 80 degrees C was measured using UV-Vis and/or (1)H NMR spectroscopy. Both forms of indolylfulgimide display high hydrolytic stability in 70/30 ethanol/water at 50 degrees C, with the Z- and C-forms degrading 1.3%/day and 1.2%/day respectively based on (1)H NMR data. At 80 degrees C in toluene the less stable Z-form lost about 20%/day.
Piñero L, Calderón X, Rodríguez J
… +4 more, Nieves I, Arce R, García C, Oyola R
J Photochem Photobiol A Chem
· 2008 Jul · PMID 19582136
·
Full text
Phenothiazines derivatives are versatile compounds that are used in many fields, depending on the type and position of the substitution on the parent molecule. The photochemical, photophysical and electrochemical propert...Phenothiazines derivatives are versatile compounds that are used in many fields, depending on the type and position of the substitution on the parent molecule. The photochemical, photophysical and electrochemical properties of several phenothiazine derivatives have been previously reported in detail. However, no reports have been presented for 2-aminophenothiazine (APH), a candidate that provides for the further chemical modification and the introduction of specific substituents. In this work, the photophysical and electrochemical properties of APH were measured in acetonitrile. The APH ground state absorption and fluorescence spectrum (phi(f) < 0.01) are similar to the corresponding that of PH parent molecule. A mono exponential decay fluorescence lifetime of 0.65 ns was determined for APH in acetonitrile. Characterization of the 355 nm nanosecond laser flash photolysis transient species reveals the presence of the triplet-triplet transient intermediate with a high intersystem crossing quantum yield (phi(T) = 0.72 +/- 0.07), indicating that the APH main excited state deactivation channel is intersystem crossing. The oxidation potential of APH is lower than phenothiazine parent molecule ((0.38 V vs 0.69 V vs Ag/AgCl(sat)). Altogether, these results show that APH has photochemical and photophysical properties similar to the phenothiazine parent molecule, but with the possibility of providing an amino functionality at 2-position for further chemical modification.