Advanced Drug Delivery Strategies for Overcoming Biological Barriers: Tumor Microenvironment and Blood–Brain Barrier

Therapeutic efficacy for malignancies and neurological disorders is fundamentally restricted by biological barriers, particularly the complex tumor microenvironment (TME) and selective blood–brain barrier (BBB). This review analyzes advanced drug delivery technologies engineered to overcome these obstacles. For TME penetration, stimuli-responsive nanocarriers enable spatiotemporally controlled drug release, while tumor-penetrating peptide functionalized nanoparticles enhance deep tumor diffusion; metal-organic frameworks further facilitate combinatorial therapy via microenvironment-triggered payload release. Regarding BBB transcendence, receptor-mediated transcytosis strategies significantly improve brain uptake, and physical-assisted approaches achieve localized barrier modulation. Bioinspired platforms—notably cell-membrane-coated nanoparticles and exosomes—demonstrate superior immune evasion and tissue-specific accumulation. Despite promising clinical progress exemplified by ANG1005 and focused ultrasound-assisted liposomal doxorubicin, translation challenges persist, including TME heterogeneity, scalable manufacturing complexities, and long-term biosafety. Future development prioritizes multifunctional theranostic systems integrating barrier-remodeling agents, artificial intelligence (AI)-optimized nanocarrier design, and sustainable manufacturing processes. Collectively, these innovations are transforming advanced drug delivery into a core therapeutic paradigm for intractable diseases.