1：Experimental Design and Method Selection:

The study involved the synthesis of a polycationic AIE nanoprobe (PEG-PEI-TPE) and its coupling with poly(acrylic acid)-coated SPIO to yield a dual-mode fluorescence/MR imaging probe (PEG-PEI-TPE/SPIO). The methodology included characterization techniques such as 1H NMR, FTIR, DLS, TEM, and fluorescence spectroscopy.

2：Sample Selection and Data Sources:

RAW 264.7 and HeLa cells were used to evaluate the cell labeling efficiency of the probe. The T2 relaxivity was measured using a 3.0 T clinical MRI scanner.

3：7 and HeLa cells were used to evaluate the cell labeling efficiency of the probe. The T2 relaxivity was measured using a 0 T clinical MRI scanner. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Instruments used included a Bruker 400 MHz NMR spectrometer, Perkin-Elmer spectrophotometer, Malvern Nanosizer, FEI Tecnai 20 microscope, F-7000 Fluorescence spectrophotometer, HITACHI U-2910 UV–vis spectrophotometer, AA800 Perkin–Elmer atomic absorption spectroscopy, and a 3.0 T clinical MRI scanner (Siemens Sonata).

4：0 T clinical MRI scanner (Siemens Sonata). Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: The synthesis of PEG-PEI-TPE and PEG-PEI-TPE/SPIO, characterization of their properties, evaluation of fluorescence intensity and lifetime, pH-dependent fluorescence intensity change, in vitro T2 relaxivity, and cell labeling experiments were conducted.

5：Data Analysis Methods:

The fluorescence data were analyzed using an F-7000 Fluorescence spectrophotometer. The T2 relaxivity was calculated from MRI data. Cell viability was assessed using a CCK-8 kit and a microplate reader.