CAT and neoplasm: Yang et al. [107] also designed a very smart multifunctional NPs in which they encapsulated catalase in hollow silica NPs, with covalently coupled Ce6, covalently coupled CTPP (3-carboxypropyl)triphenylphosphonium bromide) to target mitochondria and modified with an acidic pH responsive charge-convertible DPEG polymer (in acidic conditions, the DPEG polymer had positives charges that enhance tumour cell internalization) and programmed death-ligand 1 (PD-L1) antibody to promote the infiltration of T lymphocytes in metastasis.