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G-quadruplex (G4) structures formed by the guanine-rich DNA regions exhibit several distinctive optical properties, including UV absorption and circular dichroism spectra. Some G4 DNA possess intrinsic UV fluorescence whose origin is not completely clear to date. In this work, we study the effect of TMPyP4 and Methylene Blue on the intrinsic fluorescence of the dimeric G4 DNA structure formed by two d(GT) sequences. We demonstrate that binding of the ligands results in quenching of the intrinsic fluorescence, although the conformation of the G4 DNA and its dimeric structure remain preserved. The binding sites of the ligands were suggested by the photoinduced oxidation of guanines and analysis of binding isoterms. We discuss how DNA-ligand complexes can affect the intrinsic fluorescence of G4 DNA.
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http://dx.doi.org/10.1007/s00249-023-01696-3 | DOI Listing |
Chembiochem
September 2025
Chemistry Department, Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow, 119991, Russia.
Nucleic acid aptamers are artificial recognition elements with great potential in biotechnology. For their effective integration into nanodevices, rational strategies for optimizing aptamer affinity and regulating activity are essential. Artificial nucleotide analogs offer versatile tools for both fundamental and applied research in the aptamer field.
View Article and Find Full Text PDFInt J Biol Macromol
September 2025
Key Laboratory of Basic and Application Research of Beiyao (Heilongjiang University of Chinese Medicine), Ministry of Education, 24 Heping Road, Harbin, 150040, PR China. Electronic address:
Polysaccharides encounter significant challenges in vivo pharmacokinetic studies because of their complex structures and the limitations of current detection methods, thereby impeding their development and biomedical applications. This study systematically investigated the oral absorption characteristics and tissue distribution of ME-2, a homogeneous polysaccharide from Auricularia auricula-judae, using a dual-labeling pharmacokinetic approach. First, a fluorescein-5-thiosemicarbazide (FTSC)-based quantitative method was established to analyze plasma pharmacokinetics and tissue concentrations of ME-2, demonstrating robust methodological stability (intra-/inter-day RSD < 15 %) and accuracy (recovery rate 95-103 %).
View Article and Find Full Text PDFInt J Biol Macromol
September 2025
School of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, China. Electronic address:
Quantum dots, with their superior intrinsic fluorescence and photostability, are emerging as a promising option for cancer gene therapy, diagnosis, and imaging. However, low gene delivery efficiency, insufficient targeting, and responsiveness remain challenges. To address these issues, PEI-based carbon quantum dots (CPNCs) were constructed by crosslinking polyethylenimine quantum dots (PQDs) with carbon quantum dots (CQDs) via disulfide bonds.
View Article and Find Full Text PDFJ Hazard Mater
August 2025
Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, PR China. Electronic address:
For the first time, long-wavelength red emission carbon dots (R-CDs) were prepared as ratiometric fluorescent and colorimetric dual-mode sensors for detecting ClO using a simple one-step hydrothermal method. R-CDs exhibited intrinsic red fluorescence at 587 nm. Upon interaction with ClO, a new and enhanced green fluorescence at 535 nm was observed, which was attributed to resulting from the oxidation of surface hydroxyl (-OH) groups to carbonyl (CO) groups.
View Article and Find Full Text PDFBioorg Chem
September 2025
Aix Marseille Univ., CNRS UMR 7325 Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), Campus de Luminy, 13288 Marseille cedex 09, France. Electronic address:
In the field of theranostics, triaminophenaziniums are promising molecules due to their intrinsic properties such as an absorbance beyond 500 nm associated with large molar extinction coefficients, high fluorescence quantum yields, as well as phototoxicity. This study explored how three triaminophenazinium salts relate in structure and activity, highlighting their potential as theranostic agents. The nature of the moiety in position 2 of the dyes was varied from H, to -CH or -Bu.
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