Structure and dynamics of poly(methacrylic acid) and its interpolymer complex probed by covalently bound rhodamine-123.

The dynamics and structural characteristics of polymethacrylic acid bound rhodamine-123 (PMAA-R123) and its interpolymer complex formed through hydrogen bonding between the monomeric units with poly(vinylpyrrolidone) were investigated using single molecular fluorescence studies. The time resolved fluorescence anisotropy decay of PMAA-R123 under acidic pH exhibits an associated anisotropy decay behavior characteristic of two different environments experienced by the fluorophore with one shorter and another longer rotational correlation time. The anisotropy decay retains normal bi-exponential behavior under neutral pH.

Human Exfoliated Deciduous Teeth Stem Cells: Features and Therapeutic Effects on Neurogenerative and Hepatobiliary-pancreatic Diseases.

Stem cells can multiply into more cells with similar types in an undifferentiated form and differentiate into other types of cells. The great success and key essence of stem cell technology is the isolation of high-quality Mesenchymal Stem Cells (MSCs) with high potency, either with multipotent or pluripotent property. In this line, Stem cells from Human Exfoliated Deciduous teeth (SHEDs) are highly proliferative stem cells from dental pulp and have multipoint differentiation capacity.

Colorimetric and fluorescence sensing of Zn ion and its bio-imaging applications based on macrocyclic "tet a" derivative.

We report on the synthesis and characterization of trans N, N'-di-substituted macrocyclic "tet a" probe (L) for metal ion sensing. Both the colorimetric and fluorescent titration studies are performed with different metal ions. The results have suggested that the probe L is very selective and sensitive towards Zn ions with significant changes in color.

Nanosecond laser ablation enhances cellular infiltration in a hybrid tissue scaffold.

Hybrid tissue engineered (HTE) scaffolds constituting polymeric nanofibers and biological tissues have attractive bio-mechanical properties. However, they suffer from small pore size due to dense overlapping nanofibers resulting in poor cellular infiltration. In this study, using nanosecond (ns) laser, we fabricated micro-scale features on Polycaprolactone (PCL)-Chitosan (CH) nanofiber layered bovine pericardium based Bio-Hybrid scaffold to achieve enhanced cellular adhesion and infiltration.

Role of photoionization on the dynamics and mechanism of photoinduced electron transfer reaction of coumarin 307 in micelles.

The dynamics and mechanism of the photoinduced electron transfer (PET) reaction between coumarin 307 (C307) and aromatic amines in micelles have been studied by using steady-state (S-S) and time-resolved (T-R) absorption and fluorescence spectroscopy. Based on the fluorescence quenching time scale, PET in micelles is grouped into two types: (i) ultrafast electron transfer (ET) due to the close contact of the donor and acceptor in micelles and (ii) diffusion averaged dynamic electron transfer (DADET) which is controlled by the diffusion of the reactants in micellar Stern layer and diffusion of the micelles. The DADET does not affect the photoionization and solvation processes whereas ultrafast ET competes with the photoionization and faster than the solvation process.

Existence of a new emitting singlet state of proflavine: femtosecond dynamics of the excited state processes and quantum chemical studies in different solvents.

Proflavine (3,6-diaminoacridine) shows fluorescence emission with lifetime, 4.6 ± 0.2 ns, in all the solvents irrespective of the solvent polarity.

Photoionization and time-dependent stokes shift of coumarin 307 in soft matter: solvation and radical-ion pair recombination dynamics.

Photoionization, fluorescence time-dependent Stokes shift (TDSS), and rotational dynamics of coumarin 307 (C307) have been investigated in soft matter system such as micelles using time-resolved transient absorption and fluorescence spectroscopy. Photoionization of C307 leads to the formation of coumarin radical cation and hydrated electron, which were characterized by their respective transient absorption. The photoionization yields are significantly higher in anionic sodium dodecyl sulfate (SDS) micelle than in cationic cetyltrimethylammonium bromide (CTAB) and neutral Triton X-100 (TX-100) micelles, indicating the influence of micellar surface charge on the efficient separation of radical cation-hydrated electron pair.

Anomalous association and fluorophore influence on the position of dimethylaniline in micelles: fluorescence quenching of 1,8-acridinedione.

Fluorescence quenching of 9,10-dimethyl-3, 4,6,7,9,10-hexahydro-1,8(2H,5H) acridinedione (ADD) dye by N,N-dimethylaniline (DMA) in SDS and CTAB were studied by steady state fluorescence and time resolved techniques. The Stern-Volmer plots for the quenching of ADD by DMA is found to be linear and the Stern-Volmer constant K(SV) depends on the micellar concentration. The fluorescence quenching analysis reveals the binding of DMA with the micelles.

A novel fluorophore with dual fluorescence: local excited state and photoinduced electron-transfer-promoted charge-transfer state.

Absorption and emission spectra of 9-N,N-dimethylaniline decahydroacridinedione (DMAADD) have been studied in different solvents. The fluorescence spectra of DMAADD are found to exhibit dual emission in aprotic solvents and single emission in protic solvents. The effect of solvent polarity and viscosity on the absorption and emission spectra has also been studied.

Excited-state behavior and photoionization of 1,8-acridinedione dyes in micelles--comparison with NADH oxidation.

The photophysics and photochemistry of 1,8-acridinedione dyes, which are analogues of reduced nicotinamide adenine dinucleotide (NADH), are studied in anionic and cationic micelles. Acridinedione dyes (ADDs) are solubilized in micelles at the micelle-water interface and are in equilibrium between the aqueous and micellar phase. The binding of the ADDs with micelles is attributed to hydrophobic interactions and the binding constants are determined with steady-state and time-resolved techniques.