Next-generation nanocarriers for precision antitumor therapy: from passive targeting to intelligent response.

The evolution of nanocarrier-based drug delivery systems has transformed the paradigm of cancer therapeutics, advancing from conventional cytotoxic formulations to intelligent, adaptive nanosystems capable of precision targeting. Early-generation nanocarriers exploited the enhanced permeability and retention (EPR) effect for passive tumor accumulation, yet their therapeutic efficiency remained constrained by tumor heterogeneity, limited penetration, and off-target toxicity. Emerging nanotechnologies now integrate active targeting, stimuli-responsive components, and biomimetic strategies to achieve spatiotemporal control over drug release and tumor-selective action. These "intelligent" nanocarriers are designed to recognize molecular signatures, respond dynamically to tumor microenvironmental cues such as pH, redox gradients, hypoxia, and enzymatic activity, and even engage in real-time feedback through imaging or biosensing modules. In addition, hybrid and multifunctional platforms-combining liposomes, micelles, dendrimers, polymeric nanoparticles, and inorganic systems-offer programmable functionality and synergistic delivery of chemotherapeutic, gene-editing, and immunomodulatory agents. This review delineates the mechanistic basis of passive and active targeting, highlights recent innovations in stimuli-responsive and biomimetic nanocarriers, and explores translational and regulatory perspectives shaping their clinical journey. By integrating nanotechnology with systems biology and artificial intelligence, next-generation nanocarriers promise to redefine the landscape of precision antitumor therapy.