Fig. 2. Viability of 4T1 cells treated with/without UCNP@TBD followed by laser irradiation (Ex: 808 nm, 2.5 W cm⁻²) for 40 min or treated with only UCNP@TBD or laser irradiation (Ex: 808 nm, 2.5 W cm⁻²). [UCNP@TBD] = 50 μg mL⁻¹ based on TBD, [calcein-AM] = 2 μM, [PI] = 2 μM, calcein-AM (Ex: 488 nm; Em: 505–525 nm) and propidium iodide (PI) (Ex: 552 nm; Em: 605–625 nm). Scale bar: 200 μm.