This study compared the photoluminescence (PL) stabilities of formamidinium (FA) and methylammonium (MA) in lead iodide perovskite quantum dots (QDs). To exclude other factors, such as size and purity, that may affect stability, MAPbI₃ and FAPbI₃ QDs with nearly identical sizes (~10.0 nm) were synthesized by controlling the ligand concentration and synthesis temperature. Transmission electron microscopy images and X‐ray diffraction patterns confirmed homogeneous single‐phase perovskite structures. Additionally, the bandgaps and sizes of the synthesized QDs closely matched those of the infinite quantum well model, which guaranteed that the photostability was solely caused by the different organic molecules in the two QDs. We analyzed the PL peak centers and full‐width at half maximum of the QDs for 32 days. The enhanced stability of FAPbI₃ was found to be caused by the nearly zero redshift (1.615 eV) of its PL peak, in contrast to the redshift (1.685→1.670 eV) of MAPbI₃.

Metabolic dysfunction-associated steatohepatitis (MASH) is characterized by hepatic steatosis, metabolic stress, and inflammation. Although free fatty acid (FFA)-based in vitro models are widely used, how OA:PA ratios shape hepatocellular phenotypes remains incompletely characterized. HepG2 cells were treated with oleic acid (OA), palmitic acid (PA), or four OA:PA mixtures (O1P1, O2P1, O3P2, O1P2) for 24 or 48 h. OA and OA:PA mixtures were evaluated at 500 μM total FFA (O2P1: 333.3 μM OA + 166.7 μM PA; O3P2: 300 μM OA + 200 μM PA), whereas PA alone was evaluated at 200 μM. Cell viability, lipid accumulation, ultrastructure, oxidative response, secreted cytokines, and molecular responses were evaluated. Distinct OA:PA ratios generated discrete hepatocellular states rather than a linear steatosis-to-lipotoxicity continuum. O3P2 produced a steatosis-dominant phenotype with pronounced lipid accumulation and relatively limited stress signaling. In contrast, O2P1 combined substantial lipid accumulation with elevated DCF fluorescence, AMP-activated protein kinase (AMPK) phosphorylation, nuclear factor kappa B (NF-κB)-associated inflammatory signaling, and interleukin-8 (IL-8) secretion, representing a pronounced stress-responsive phenotype with selected MASH-relevant features. Selected responses were also evaluated in SNU-449 cells, revealing cell-line-specific patterns. Collectively, these findings support a phenotype-oriented framework for OA:PA ratio selection in hepatocyte-based in vitro MASH modeling.