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Page 4 of 18 Wang et al. Cancer Drug Resist. 2026;9:8

irradiated under white light (equipped with a UV cut filter, 10 mW·cm ) for 10 min, and fluorescence
-2
emission at 525 nm was monitored, with an excitation wavelength (λ ) of 488 nm.
ex
For the quantitative determination of singlet oxygen quantum yield (Φ ) via O phosphorescence detection,
1
Δ
2
PTTP-DCns and RB were dissolved in deuterated PBS and adjusted to the same absorbance at 520 nm (A =
0.7). The solutions were degassed by nitrogen bubbling for 10 min. The near-infrared emission between
1,200-1,400 nm was collected. A fourth-order polynomial fitting method was used to fit the data of degassed
PTTP-DCns from 1,200-1,230 nm and 1,310-1,370 nm. The fitting curve was used to simulate the emission
spectrum of PTTP-DCns as background to get the O phosphorescence spectrum in PTTP-DCns solution.
1
2
Then, the O phosphorescence spectra were fitted by a GaussAmp fitting method in the origin software. The
1
2
1 O quantum yield (Φ ) can also be calculated as :
[27]
Δ
2

Φ Δ = Φ Δ (1)

where A and A are the intensity of O phosphorescence generated from photosensitization of testing
1
s
RB
2
samples and RB, respectively, by calculating the integral area of the final GaussAmp fitting curve. Φ (0.76)
ΔRB
is used as the O quantum yield of RB in PBS buffer.
1
2
Cell lines and cell incubation conditions
Michigan Cancer Foundation-7/adriamycin-resistant (MCF-7/ADR, DOX-resistant human breast cancer cell
line) cells were obtained from Shanghai Jinyuan Biotechnology Co., Ltd. (China) and cultured in Roswell
Park Memorial Institute (RPMI) 1640 medium supplemented with 10% fetal bovine serum (FBS), 1%
penicillin-streptomycin (P/S) and 0.5 μg·mL DOX.
-1
HCC827/IR (icotinib-resistant human lung cancer cell line) cells were obtained from Ningbo University
Health Science Center (China) and cultured in RPMI 1640 medium supplemented with 10% FBS, 1% P/S and
10 μM icotinib.

HEK293 (human kidney cell line) cells were obtained from Wuhan Pricella Biotechnology Co., Ltd (China)
and cultured in high-glucose Dulbecco’s Modified Eagle Medium (DMEM) supplemented with 10% FBS and
1% P/S.

Cells were all cultured at 37 °C in a humidified incubator containing 5% (v/v) CO .
2

Cellular uptake
To reduce the fluorescence interference of DOX, MCF-7/ADR cells were cultured without DOX for 2-3
generations before confocal laser scanning microscope (CLSM) imaging.

The cellular uptake of the PTTP-DCns compounds in MCF-7/ADR cells was assessed under both short-term
and long-term conditions. For all experiments, cells were treated with 1 µM of the specified compound in
serum-supplemented medium. For short-term monitoring, cells treated for 2 h were analyzed by flow
cytometry. For long-term tracking, CLSM was performed at intervals from 15 min to 24 h post-treatment
without prior washing.

Cellular uptake inhibition
Following adhesion for 12 h, the MCF-7/ADR cells were pre-treated for 30 min under different conditions:
either with serum- and phenol red-free medium at 4 °C, or with the same medium containing specific
inhibitors [chlorpromazine (CPZ) at 10 µg·mL , genistein (Gen) at 50 µg·mL , or dynasore (Dyn) at 80 µM]
-1
-1
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