Photophysics of thiazole orange in deep eutectic solvents

Machine-Learning-Driven G-Quartet-Based Circularly Polarized Luminescence Materials

Circularly polarized luminescence (CPL) materials have garnered significant interest due to their potential applications in chiral functional devices. Synthesizing CPL materials with a high dissymmetry factor (glum ) remains a significant challenge. Inspired by efficient machine learning (ML) applications in scientific research, this work demonstrates ML-based techniques for the first time to guide the synthesis of G-quartet-based CPL gels with high glum values and multiple chiral regulation strategies. Employing an "experiment-prediction-verification" approach, this work devises a ML classification and regression model for the solvothermal synthesis of G-quartet gels in deep eutectic solvents. This process illustrates the relationship between various synthesis parameters and the glum value. The decision tree algorithm demonstrates superior performance across six ML models, with model accuracy and determination coefficients amounting to 0.97 and 0.96, respectively. The screened CPL gels exhibiting a glum value up to 0.15 are obtained through combined ML guidance and experimental verification, among the highest ones reported till now for biomolecule-based CPL systems. These findings indicate that ML can streamline the rational design of chiral nanomaterials, thereby expediting their further development.

Switching G-quadruplex to parallel duplex by molecular rotor clustering

Switching of G-quadruplex (G4) structures between variant types of folding has been proved to be a versatile tool for regulation of genomic expression and development of nucleic acid-based constructs. Various specific ligands have been developed to target G4s in K⁺ solution with therapeutic prospects. Although G4 structures have been reported to be converted by sequence modification or a unimolecular ligand binding event in K⁺-deficient conditions, switching G4s towards non-G4 folding continues to be a great challenge due to the stability of G4 in physiological K⁺ conditions. Herein, we first observed the G4 switching towards parallel-stranded duplex (psDNA) by multimolecular ligand binding (namely ligand clustering) to overcome the switching barrier in K⁺. Purine-rich sequences (e.g. those from the KRAS promoter region) can be converted from G4 structures to dimeric psDNAs using molecular rotors (e.g. thioflavin T and thiazole orange) as initiators. The formed psDNAs provided multiple binding sites for molecular rotor clustering to favor subsequent structures with stability higher than the corresponding G4 folding. Our finding provides a clue to designing ligands with the competency of molecular rotor clustering to implement an efficient G4 switching.

p-Aminostyryl thiazole orange derivatives for monitoring mitochondrial viscosity in live cells

Viscosity of cell microenvironment plays a significant role in maintaining the normal life activities of cells. Particularly, the abnormal viscosity in mitochondria is closely associated with lots of diseases and cellular dysfunctions. Herein, we developed a group of p-aminostyryl thiazole orange derivatives with different amino side chains. These probes showed good fluorescence response to viscosity with twisted intramolecular charge transfer mechanism, among them, the probes with diethylamino (TOB), dibutylamino (TOC) and pyrrolidin (TOE) side chains showed better response to the viscosity with 78-fold, 55-fold, and 88-fold fluorescence enhancement in 95% glycerol solution respectively. TOB, TOC, and TOE could enter live cells and mainly located in mitochondria. Treatment HeLa cells with nystatin, lipopolysaccharide or oleic acid caused significant fluorescence enhancement of these probes, suggesting the good potential for monitoring the variation of mitochondrial viscosity, as well as for investigating the related physiological process of inflammation and lipid metabolism.