1：Experimental Design and Method Selection:

The study involved synthesizing a bifunctional quadrupolar dye and covalently grafting it onto phosphorus-based dendrimers to create nanoparticles. Photophysical properties were measured using UV-Vis absorption, fluorescence spectroscopy, singlet oxygen quantum yield determination, and two-photon absorption cross-section measurements. Cellular studies included confocal microscopy for imaging and MTS/MTT assays for cytotoxicity under various conditions.

2：Sample Selection and Data Sources:

MCF-7 human breast cancer cells were used for in vitro experiments. Samples included the synthesized dye (10), first-generation dendrimer (2-G1), and second-generation dendrimer with water-solubilizing groups (2-G2).

3：2). List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included Jasco V-570 spectrophotometer, Edinburgh Instruments FLS920 spectrometer, Horiba Jobin Yvon Fluorolog-3, Ti-sapphire laser for two-photon measurements, Zeiss LSM 780 confocal microscope with Chameleon Ultra II laser, Bruker Avance AV 300 NMR, Micromass MS/MS ZABSpec TOF for mass spectrometry, and various chemicals for synthesis.

4：Experimental Procedures and Operational Workflow:

Synthesis involved multiple steps including Mitsunobu condensation, Wittig reactions, Sonogashira couplings, and dendrimer functionalization. Photophysical measurements were conducted in THF or dichloromethane. Cellular experiments involved incubating cells with dendrimers, staining with markers (Hoechst 33342, CellMask), irradiation with lasers, and assessing viability via MTS/MTT assays.

5：Data Analysis Methods:

Data were analyzed using standard spectroscopic techniques, fluorescence lifetime measurements with reconvolution fit, and statistical analysis of cell viability assays (mean ± SD).