Nanomedicines Based on Responsive Nanocarriers for Cancer Therapy

Nanotechnology has been widely used in drug design in recent years, showing great potential and advantages in tumor therapy. However, the application of most traditional nanomedicines is still limited by low drug loading rate, poor targeting ability, and systemic toxicity. Based on the characteristics of tumor microenvironments, numerous studies indicate that the construction of stimuli-responsive nanocarriers can effectively solve the above problems by improving delivery efficiency, reducing side effects, and enhancing targeting. A significant feature of responsive nanocarriers is that they can release and activate drugs at specific sites under stimulus, including internal stimuli (e.g., pH, reactive oxygen species (ROS), glutathione (GSH), enzyme, hypoxia, adenosine-triphosphate (ATP), etc.) and external stimuli (e.g., light, thermo, ultrasound, etc.). Of note, learning about various pathways of responses can enable researchers to effectively design responsive nanocarriers for tumor therapy. Herein, this review focuses on the stimuli-responsive strategies of nanocarriers for tumor therapy. In addition, the role of responsive nanocarriers in synergistic tumor therapy is also discussed. The expectation of this review is to provide ideas for the design of practical and effective responsive nanocarriers. Internal and external stimuli-responsive nanocarriers, focusing on the single-responsive, dual-responsive, and multi-responsive nanocarriers, are reviewed for tumor-targeted drug delivery and multi-synergistic tumor therapy. Additionally, the prospect of responsive nanomedicines in clinical translation is also discussed.image