Cavity Lasing of Thioflavin T in the Condensed Phase for Discrimination between Surface Interaction and β-Sheet Groove Binding in Alzheimer-Linked Peptides.

This study investigates the lasing effects in a Fabry-Perot cavity to discern the binding interactions of thioflavin T (ThT) with various peptides associated with Alzheimer's disease, including Aβ(1-42), KLVFFA, and diphenylalanine (FF) in the condensed phase. Utilizing kinetic lasing measurements, the research explores ThT emission enhancements due to specific groove binding in β-sheet structures and highlights additional contributions from weak surface interactions and solvent-solute interactions. Lasing spectroscopy reveals a lack of transition of the FF system from its native state to an amyloid-like structure, challenging traditional ThT assay interpretations.

Thioflavin T─a Reporter of Microviscosity in Protein Aggregation Process: The Study Case of α-Synuclein.

Thioflavin T (ThT) informed microviscosity changes can be used to monitor protein aggregation. Steady-state, time-resolved and lasing spectroscopy were used to detect transient states in α-synuclein - a protein associated with Parkinson's disease. The major focus was on the nucleation phase, where conventional ThT fluorescence assay lacks appropriate sensitivity to detect early stage oligomers.

Role of Alkali Cations in DNA-Thioflavin T Interaction.

This study investigates the role of alkali cations in modulating the interaction between deoxyribonucleic acid (DNA) and Thioflavin T (ThT) in dilute and condensed phases. The emission characteristics of ThT were analyzed in the presence of double-stranded DNA and G-quadruplex structures with a focus on the effects of four cations: sodium, potassium, calcium, and magnesium. The ThT emission in double-stranded DNA was influenced by direct DNA binding and steric hindrance within the hydration shell of DNA, which was modulated by the presence of alkali cations.

Cavity Lasing Characteristics of Thioflavin T and Thioflavin X in Different Solvents and Their Interaction with DNA for the Controlled Reduction of a Light Amplification Threshold in Solid-State Biofilms.

The lasing characteristics of Thioflavin T (ThT) and Thioflavin X (ThX) dyes were investigated in solvents with increasing viscosity: water, ethanol, butanol, ethylene glycol, and glycerol and three forms of DNA (double-helix natural, fragmented, and aggregated). The results identified that lasing thresholds and photostability depend on three critical factors: the solvation shell surrounding dye molecules, the organization of their dipole moments, which is driven by the DNA structure, and the molecules diffusion coefficient in the excitation focal spot. The research highlights that dye doped to DNA accumulated in binding sites fosters long-range dye orientation, facilitating a marked reduction of lasing thresholds in the liquid phase as well as amplified spontaneous emission (ASE) thresholds in the solid state.

Two-photon excited lasing for detection of amyloids in brain tissue.

Two-photon excitation of emissive markers with near-infrared (NIR) light is of a particular interest for imaging in biology and medicine because NIR light is relatively weakly absorbed and scattered by tissues. At the same time the mechanism of two-photon absorption allows excitation of molecules located deep inside a scattering medium. In this work we demonstrate that the two-photon excitation combined with the effect of light amplification in the stimulated emission process provides a sensitive method for detecting amyloids of different forms.