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Synchronously Amplified Photoacoustic Image Recovery (SAPhIRe) offers improved background suppression using non-linear properties of modulatable contrast agents. Using SAPhIRe, multiple contrast agents in the same absorption window can be detected independently based on their unique triplet-state lifetimes. Here, we have demonstrated the unmixing of rose bengal and eosin Y signals from solution based on triplet-state lifetime mapping using both fluorescence and photoacoustics. Varying the pump-probe delay enables resolution and recovery of fast-decaying rose bengal and of slowly decaying eosin Y modulated photoacoustic signals, resulting from optically gated triplet state residence. Distinct images were reconstructed within tissue-mimicking phantom using the fitting coefficients of triplet-state lifetimes. Fluorescence was used to screen for modulation prior to photoacoustic imaging. The results suggest that lifetime unmixing can be utilized to simultaneously detect multiple pathologies with overlapping spectra using photoacoustic imaging.

UV-like DNA damage is created in the dark by chemiexcitation, in which UV-activated enzymes generate reactive oxygen and nitrogen species that create a dioxetane on melanin. Thermal cleavage creates an electronically excited triplet-state carbonyl whose high energy transfers to DNA. Screening natural compounds for the ability to quench this energy identified polyenes, polyphenols, mycosporine-like amino acids, and related compounds better known as antioxidants. To eliminate false positives such as ROS and RNS scavengers, we then used the generator of triplet-state acetone, tetramethyl-1,2-dioxetane (TMD), to excite the triplet-energy reporter 9,10-dibromoanthracene-2-sulfonate (DBAS). Quenching measured as reduction in DBAS luminescence revealed three clusters of 50% inhibitory concentration, ~50 μM, 200–500 μM, and >600 μM, with the former including sorbate, ferulic acid, and resveratrol. Representative triplet-state quenchers prevented chemiexcitation-induced “dark” cyclobutane pyrimidine dimers (dCPD) in DNA and in UVA-irradiated melanocytes. We conclude that (i) the delocalized pi electron cloud that stabilizes the electron-donating activity of many common antioxidants allows the same molecule to prevent an electronically excited species from transferring its triplet-state energy to targets such as DNA and (ii) the most effective class of triplet-state quenchers appear to operate by energy diversion instead of electron donation and dissipate that energy by isomerization.

This investigation delves into the UV photodissociation of pivotal amino acids (Alanine, Glycine, Leucine, Proline, and Serine) at 213 nm, providing insights into triplet-state deactivation pathways. Utilizing a comprehensive approach involving time-dependent density functional calculations (TD-DFT), multi-configurational methods, and ab-initio molecular dynamics (AIMD) simulations, we scrutinize the excited electronic states (T 1 , T 2 , and S 1 ) subsequent to 213 nm excitation. Our findings demonstrate that α-carbonyl C-C bond-breaking in triplet states exhibits markedly lower barriers than in singlet states (below 5.0 kcal mol -1 ). AIMD simulations corroborate the potential involvement of triplet states in amino acid fragmentation, underscoring the significance of accounting for these states in photochemistry. Chemical bonding analyses unveil distinctive patterns for S 1 and T 1 states, with the asymmetric redistribution of electron density characterizing the C-C breaking in triplet states, in contrast to the symmetric breaking observed in singlet states. This research complements recent experimental discoveries, enhancing our comprehension of amino acid reactions in the interstellar medium., (© 2023 Wiley-VCH GmbH.)

Synchronously Amplified Photoacoustic Image Recovery (SAPhIRe) offers improved background suppression using non-linear properties of modulatable contrast agents. Using SAPhIRe, multiple contrast agents in the same absorption window can be detected independently based on their unique triplet-state lifetimes. Here, we have demonstrated the unmixing of rose bengal and eosin Y signals from solution based on triplet-state lifetime mapping using both fluorescence and photoacoustics. Varying the pump-probe delay enables resolution and recovery of fast-decaying rose bengal and of slowly decaying eosin Y modulated photoacoustic signals, resulting from optically gated triplet state residence. Distinct images were reconstructed within tissue-mimicking phantom using the fitting coefficients of triplet-state lifetimes. Fluorescence was used to screen for modulation prior to photoacoustic imaging. The results suggest that lifetime unmixing can be utilized to simultaneously detect multiple pathologies with overlapping spectra using photoacoustic imaging., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)

High resolution spectra and luminescent lifetimes of 6 europium(III)–cinnamic acid complex {[Eu 2 L 6 (DMF)(H 2 O)]·nDMF·H 2 O} m (L = cinnamic acid I , 4-methyl-cinnamic acid II , 4-chloro-cinnamic acid III, 4-methoxy-cinnamic acid IV , 4-hydroxy-cinnamic acid V , 4-nitro-cinnamic acid VI ; DMF = N, N-dimethylformamide, C 3 H 7 NO) were recorded from 8 K to room temperature. The energy levels of Eu 3 + in these 6 complexes are obtained from the spectra analysis. It is found that the energy levels of the central Eu 3 + ions are influenced by the nephelauxetic effect, while the triplet state of ligand is lowered by the p–π conjugation effect of the para-substituted functional groups. The best energy matching between the ligand triplet state and the central ion excited state is found in complex I . While the other complexes show poorer matching because the gap of 5 D 0 and triplet state contracts. [ABSTRACT FROM AUTHOR]

UV-like DNA damage is created in the dark by chemiexcitation, in which UV-activated enzymes generate reactive oxygen and nitrogen species that create a dioxetane on melanin. Thermal cleavage creates an electronically excited triplet-state carbonyl whose high energy transfers to DNA. Screening natural compounds for the ability to quench this energy identified polyenes, polyphenols, mycosporine-like amino acids, and related compounds better known as antioxidants. To eliminate false positives such as ROS and RNS scavengers, we then used the generator of triplet-state acetone, tetramethyl-1,2-dioxetane (TMD), to excite the triplet-energy reporter 9,10-dibromoanthracene-2-sulfonate (DBAS). Quenching measured as reduction in DBAS luminescence revealed three clusters of 50% inhibitory concentration, ~50 μM, 200–500 μM, and >600 μM, with the former including sorbate, ferulic acid, and resveratrol. Representative triplet-state quenchers prevented chemiexcitation-induced "dark" cyclobutane pyrimidine dimers (dCPD) in DNA and in UVA-irradiated melanocytes. We conclude that (i) the delocalized pi electron cloud that stabilizes the electron-donating activity of many common antioxidants allows the same molecule to prevent an electronically excited species from transferring its triplet-state energy to targets such as DNA and (ii) the most effective class of triplet-state quenchers appear to operate by energy diversion instead of electron donation and dissipate that energy by isomerization. [ABSTRACT FROM AUTHOR]

Abstract: Photophysical and spectroscopic properties of phenosafranine were investigated in 21 solvents, including pure aprotic solvents and pure and binary protic solvent mixtures. It was found that these properties are highly dependent of the nature of the medium in protic solvents. Characteristic parameters such as the Stokes’ shift, the fluorescence quantum yield and lifetime and the T–T absorption maxima frequencies showed a very clean solvent dependence, with a strong incidence of the specific interactions of phenosafranine with solvent molecules, most likely through hydrogen bonding. On the other hand, in aprotic solvents these parameters are practically insensitive to changes in solvent properties. The experimental results in protic media suggest an increase of the dipole moment of the dye molecule as a consequence of the S0 →S1 transition, while a decrease in the dipole moment come along with the T1 →T n transition. In selected protic solvents, the photophysical kinetic parameters were obtained from fluorescence quantum yield and lifetime determinations and intersystem-crossing quantum yields. Their solvent dependence is discussed. [Copyright &y& Elsevier]

In this paper, the photophysical and photosensitive properties of Elsinochrome A (EA), another member of perylenequinone photosensitizers derived via artificially biological synthesis, were studied by taking hypocrellin A (HA) and hypocrellin B (HB) as the references. It was found that the quantum yield of singlet oxygen produced via the photosensitization of EA was 0.98 with HB (0.84) as a reference. Furthermore, the semiquinone anion could be produced via photosensitization of EA in oxygen-free solution. Besides, taking advantage of nanosecond time-resolved spectral technique, the transient triplet absorption spectra and the lifetime of EA in cyclohexane were determined by the use of the ground-state depletion method. [ABSTRACT FROM AUTHOR]

This paper deals with photophysical characterization of some synthetic porphyrins and phthalocyanines as well as natural chlorophylls and bacteriochlorophylls as attractive multifunctional organic materials for novel molecular photovoltaics and for photodynamic therapy or diagnosis of cancerous tissues. The following spectral methods were used in our investigations: electronic absorption, fluorescence, steady-state photoacoustic spectroscopy and time-resolved optoacoustic spectroscopy to get insight into the mechanisms responsible for molecular processes occurring in dyes upon light illumination. Spectral study was supported by photoelectric examination. The spectral parameters of dyes which are essential for photovoltaics and/or photodynamic therapy/diagnosis were estimated: absorption molar coefficients, fluorescence quantum yields, natural life-times, thermal deactivation parameters, quantum yields of triplet-state population, triplet-state thermal relaxation decay. It was shown that some synthetic porphyrins, phthalocyanines and natural (bacterio)chlorophylls can be potentially used as functional materials for both optoelectronics and/or medicine. [ABSTRACT FROM AUTHOR]

Five thousand and eight hundred publicly available expressed sequence tags (ESTs) of Phytophthora sojae were electronically searched and 415 simple sequence repeats (SSRs) were identified in 369 ESTs. The average density of SSRs was one SSR per 8.9 kb of EST sequence screened. The most frequent repeats were trinucleotide repeats (50.1%) and the least frequent were tetranucleotide repeats (8.2%). Forty primer pairs were designed and tested on 5 strains of P. sojae. Thirty-three primer pairs had successful PCR amplifications. Of the 33 functional primer pairs, 28 primer pairs produced characteristic SSR bands of the expected size, and 15 primer pairs (45.5%) detected polymorphism among 5 tested strains of P. sojae. Based on the polymorphisms detected with 20 EST-SSR markers, the 5 tested strains of P. sojae were clustered into 3 groups. In this study, the SSR markers of P. sojae were developed for the first time. These markers could be useful for identification, genetic variation study, and molecular mapping of P. sojae and its relative species. [ABSTRACT FROM AUTHOR]