“…[33][34][35] Numerous drug delivery systems that exhibit responsiveness and active targeting capabilities have been developed utilizing the mesoporous silica nanoparticles (MSNs) as a foundational platform. [36][37][38][39] It was reported that the Sigma receptor, a membrane binding protein, was highly expressed in melanoma, non-small cell lung cancer, breast cancer and other tumors [40][41][42][43][44][45][46] and had a high affinity for the small molecule ligand anisidine (AA). [47][48][49] Based on the high-affinity between them, AA can be employed as a recognition molecule for the targeting of a wide range of tumour cells.…”