{Reference Type}: Journal Article {Title}: Exploring Biological Interactions: A New Pyrazoline as a Versatile Fluorescent Probe for Energy Transfer and Cell Staining Applications. {Author}: Beşer BM;Yildirim B; {Journal}: ChemistryOpen {Volume}: 12 {Issue}: 9 {Year}: 2023 09 {Factor}: 2.63 {DOI}: 10.1002/open.202300092 {Abstract}: Fluorescent dyes are used in biological systems, because they are highly sensitive and selective. In this work, we investigated the fluorescent probe properties of 2-(5-(pyridin-2-yl)-1H-pyrazol-3-yl) phenol (PYDP) in two media [sodium dodecyl sulfate (SDS) and human serum albumin (HSA)]. Energy transfer parameters, photophysical and thermodynamic parameters of probe were determined. We investigated cytotoxicity of PYDP against colorectal adenocarcinoma cell lines (HT-29), breast cancer cell lines (MCF-7) and 3T3-L1 adipocytes (3T3 L1) cells. The cell staining property of PYDP was monitored using a confocal microscope. The results showed that PYDP binds to HSA, bindings are due to electrostatic/ionic interactions, and the binding process is spontaneous. PYDP was found to exhibit negligible cytotoxicity at high concentrations, and confocal microscope images showed that PYDP stained the cytoplasm of MCF-7 cells.