Inhaled isoflurane

Subcutaneous injection of murine 4T1 cells into Balb/c mice led to the formation of primary tumors. At 21 days after 4T1 cell injection, when the tumor diameter was >7 mm (range, 7–10 mm), ten mice were divided into two groups: treated with LnNP@ZIF8 (LnNP@ZIF8) or treated with LnNP@ZIF8-DOX (LnNP@ZIF8-DOX). The mice were anesthetized using inhaled isoflurane (RWD Life Science, Shenzhen, China). The tumor site was sanitized with a 75% ethanol tincture before treatment. All the procedures were performed aseptically. Then, a 100µL mixture of the LnNPs in PBS (5 mg/mL) was injected subcutaneously into the 4T1 tumors.
Eight of ten SCID tissue-derived orthotopic mice models constructed successfully. Then, a 100 µL mixture of the LnNP@ZIF8-DOX (5 mg/mL) in PBS was injected subcutaneously into the MCF-7 WT and MCF-7 ADR tumors.
NIR-II fluorescent images were recorded at 24 h after probe injection using an in vivo imaging system equipped with an IVIS Lumina XR III in vivo imaging system (PerkinElmer, Waltham, MA, USA).
All mice were sacrificed by cervical dislocation after CO₂ euthanasia.

Ten six-to-eight-week-old female Balb/c mice were purchased from the Model Animal Research Center of Nanjing University (MARC, Nanjing, China) and maintained under specific pathogen-free conditions in the Animal Core Facility of Nanjing Medical University. The mice were anesthetized using inhaled isoflurane (RWD Life Science, Shenzhen, China). In total, 1 × 10⁵ 4T1 cells in 100 μL of PBS were injected subcutaneously into the right inguinal mammary fat pads of each animal.