The authors assessed the cytotoxicity and Twist-silencing efficiency of dual modality NPs in a mouse 4T1 cell line at different light conditions, i.e., mimicking superficial tumours 450 mW cm−2 (total light dose of 27 J cm−2) and deep tumours 110 mW cm−2 (total light dose of 6.6 J cm−2). Here, TWIST1 is linked to neoplasm.