Lv3000

HeLa cells were inoculated in a 24-well flat plate and then cultured in an atmosphere of 5% CO₂ and 95% air in Dulbecco's modified Eagle's medium (DMEM, Invitrogen) at 37 °C for 24–36 h to reach 80–90% seeding efficiency. Some HeLa cells were treated with the NDI (10 μM concentration) at 37 °C for 30 min, followed by washing three times with PBS buffer. Another portion of HeLa cells were pretreated with 10 μM the NDI in culture media for 30 min at 37 °C, and further incubated in PBS at pH 11.00, 8.00, 6.00, and 3.00 for another 10 min at 37 °C. Fluorescent images were observed under a confocal microscope (Olympus LV3000).

Following transfection of RPL9-GFP and miRNA-mCherry plasmids at 37°C for 24-48 h, the cells were transferred to a glass culture dish and grown for 12 h. The cells were fixed with 4% paraformaldehyde for 15 min at room temperature, treated with 0.3% Triton X-100 for 15 min, stained with DAPI for 10 min and directly observed with a laser confocal microscope (Olympus LV3000, Olympus Corporation).

6-Morpholinobenzo[de]isochromene-1,3-dione (1) was prepared according to references.^{38,39 (link)} All reactions were magnetically stirred under a nitrogen atmosphere and monitored by thin-layer chromatography (TLC). All solvents and chemicals were purchased from commercial sources and used without further purification unless otherwise stated.
¹H NMR and ¹³C NMR spectra were measured on a Bruker Avance 400 (400 MHz) spectrometer using DMSO-d₆ as a solvent and tetramethylsilance (TMS) as an internal standard. Electrospray ionization (ESI) mass spectra were measured with an LC-MS 2010A (Shimadzu) instrument. Absorption and fluorescent spectra were measured by using TU-1901 (Beijing Purkinje General Instrument Co., Ltd.) and F-280 (Tianjin Gangdong Technology Co., Ltd.). A pH meter (Mettler Toledo, Switzerland) was used to determine the pH. The cell imaging experiments were carried out by using a Confocal Scanning Microscope (Olympus, LV3000).