Background Atopic dermatitis (AD) is a common skin disease that is characterized by recurrent episodes of itching. Genetic variation associated with the persistence of AD has not been described for African-Americans. Objective To evaluate genetic variation of Filaggrin-2 (FLG2) in African-Americans with AD. Methods We evaluated a multiyear prospective cohort study of African-American children with AD with respect to FLG2 variation based on whole exome sequencing followed by a targeted analysis. We ultimately evaluated the association of rs rs12568784 and rs16833974 with the respect to the persistence of AD symptoms over time. Results Whole exome analysis was conducted on 60 subjects revealing premature stop codon in exon 3 at S2377X (rs12568784), X2392S (rs150529054), and a large exon 3 deletion mutation Q2053del224. Based on a priori criteria we then studied rs12568784, rs16833974 (H1249R) and Q2053del224. We noted that S2377X (OR = 0.44; 95% CI: 0.25, 0.46) and H1249R (0.23; 0.12, 0.46) were significantly less likely to be free of symptoms of AD and Q2053del224 (0.54; 0.16, 1.80) trended toward this outcome. S2377X and H1249R were in high linkage disequilibrium (D′=0.95). Conclusions In an African-American cohort with AD, FLG2 mutations were associated with more persistent AD. This is the first finding of genetic variation of a skin barrier protein in those of African ancestry with AD. Clinical Implications FLG2 variation is associated with more persistent AD in children of African ancestry.

In this report, steady state and time-resolved fluorescence along with circular dichroism (CD) spectroscopic, FTIR, and anisotropy investigations were made to reveal the nature of the interactions between human adult hemoglobin (Hb) and the isatins, 1-methylisatin (1-MI) and 1-phenylisatin (1-PI). From the analysis of the steady state and time-resolved fluorescence quenching of Hb in aqueous solution in the presence of an isatin, i.e., 1-MI, it seemed that the nature of the quenching was of static type and a mixture of both static and dynamic nature for 1-PI. The primary binding pattern between isatins and Hb has been interpreted as a combined effect of hydrophobic association and electrostatic interaction for 1-MI. For 1-PI, this was the combined effect of hydrophobic association and ionic interactions and salt bridges or/and proton transfer. The pretwisted structure of 1-PI facilitates ionic interactions with Hb. The binding constants, number of binding sites, and thermodynamic parameters had been computed. The binding average distances between the Hb-1-MI and Hb-1-PI determined from Forster's theory were found to be 4.02 and 5.28 nm, respectively. CD, steady state, and time-resolved anisotropy measurements had been done in support.

We report time-resolved photoluminescence (PL) measurements of spin-cast amorphous films of a regioregular polythiophene derivative poly[3-(4-octylphenyl)thiophene] and of annealed semicrystalline films of the same polymer with an interchain stacking distance of 5 Å. Red-shifted PL appears at long delay times in both pristine and annealed films, which we assign to interchain aggregates populated by excitation energy migration. Aggregate luminescence in annealed films exhibits a pronounced vibronic structure indicating the coupling to a CdC bond stretch with a Huang-Rhys factor S ) 2. Two types of aggregates are distinguished in annealed films: in a few picoseconds most excitations are trapped by aggregates with a large energy gap (about 1.83 eV) between the lowest excited singlet state and the ground state. Excitation energy is transferred or the aggregates relax structurally with a time constant of about 200 ps to aggregates with a smaller energy gap (about 1.75 eV). The radiative lifetime of aggregates with smaller energy gap is estimated to be about 35 ns, two times longer than that of aggregates with the larger energy gap. In spin-cast amorphous films, emission from intrachain singlet excitons has a longer lifetime than in annealed films and only high-energy-gap aggregates are populated.

In this paper the interactions of gold nanoparticles (Au NPs) and bovin serum albumin–gold nanoconjugates (BSA–GNPs) with cadmium sulfide quantum dots (CdS QDs) are investigated by using steady-state and time-resolved spectroscopic techniques under physiological conditions (pH ∼ 7). From the analysis of the steady-state and time-resolved fluorescence quenching of CdS QDs in aqueous solution in the presence of BSA–GNPs it has been inferred that fluorescence resonance (Förster type) energy transfer (FRET) is primarily responsible for the quenching phenomenon. But in the presence of only Au NPs the fluorescence quenching of CdS NPs is primarily static in nature. Thus, it is apparent that, in the presence of BSA (in the case of the bionanoconjugate system), FRET becomes operative between CdS QDs and Au NPs present in the BSA–GNPs bionanoconjugate, whereas in the absence of this biomolecule direct contact between CdS and Au NPs facilitates the formation of ground-state complex. As shown from the high-resolution transmission electron microscopy (HRTEM) images of the bionanoconjugate, formation of a thin BSA layer around the Au NPs, situated at the core, inhibits the CdS QDs to come in contact with the Au NPs. In the CdS–bionanoconjugate system, CdS and Au NPs become separated by a distance of ∼17 ± 2 Å, as observed from HRTEM measurement. It may be presumed that when Au NPs are present in the bionanoconjugate system, the system may suffer some conformational changes which facilitates the energy transfer process to occur within the CdS QDs and the Au NPs. Further investigations with similar systems would be necessary to make unequivocal assertion of this phenomenon. From the determination of the thermodynamic parameters it is apparent that the effect of van der Waals interaction is responsible for the interaction of CdS QDs with Au NPs to form ground-state complex. The effect of CdS NPs on the conformation of BSA–GNPs has been examined by analyzing CD spectra. Though the observed results demonstrate some conformational changes in the bionanoconjugate in the presence of CdS NPs, the secondary structure of the conjugate, predominantly of the α-helix, is found to retain its identity. This type of interaction between QDs and Au NPs in a protein-conjugated form provides a new insight for design and the development of FRET-based bionanosensors.

In this paper, the interaction between bovine serum albumin (BSA) and zinc oxide (ZnO) nanoparticles was investigated by fluorescence quenching spectra, circular dichroism (CD), and synchronous spectra under physiological conditions. From the analysis of the steady state and time resolved fluorescence quenching of BSA in aqueous solution in presence of ZnO it was observed that the nature of the quenching is of static-type quenching. The Stern–Volmer quenching constant KS at different temperatures were determined and the thermodynamic parameters ΔH, ΔG, and ΔS were computed. The experiment revealed that the electrostatic interaction was the predominant force in stabilizing the complex. The effect of ZnO on the conformation of BSA has been analyzed by synchronous spectra and CD spectrum. Although the observed results demonstrate some conformational changes in BSA in presence of ZnO nanoparticles, the secondary structure of BSA, predominantly of α-helix, is found to retain its identity.

Three corroles, which differ by their cavity's core, namely, diamagnetic free-base tris(pentafluorophenyl)corrole and its gallium(III) complex and the paramagnetic oxo-chromium(V) complex, were studied by steady-state and time-resolved electron paramagnetic resonance (EPR) spectroscopy. The magnetic and orientational parameters of the corroles, oriented in a nematic liquid crystal, were determined and interpreted in terms of their structure, geometry, and excited states spin dynamics. It was shown that both diamagnetic corroles, photoexcited to their triplet states, exhibit similar EPR line shapes, which is characterized by a negative zero-field splitting parameter, D, whose origin is due to molecular "stretching". Photoexcited Cr(V)O-corrole exhibits polarized ground-state EPR spectrum in emission mode. This polarization stems from the sequence of photophysical and photochemical reactions, involving the formation of the trip-quartet/trip-doublet composite states and their selective quenching via a charge transfer state.

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