Abstract
Although a number of tactics towards the fabrication and biomedical exploration of stimuli-responsive polymeric assemblies being responsive and adaptive to various factors have appeared, the controlled preparation of assemblies with well-defined physicochemical properties and tailor-made functions are still challenges. These responsive polymeric assemblies, which are triggered by stimuli, always exhibited reversible or irreversible changes in chemical structures and physical properties. However, simple drug/polymer nanocomplexes cannot deliver or release drugs into the diseased sites and cells on-demand due to the inevitable biological barriers. Hence, utilizing therapeutic or imaging agents-loaded stimuli-responsive block copolymer assemblies that are responsive to tumor internal microenvironments (pH, redox, enzyme, and temperature, etc.) or external stimuli (light and electromagnetic field, etc.) have emerged to be an important solution to improve therapeutic efficacy and imaging sensitivity through rationally designing as well as self-assembling approaches. In this review, we summarize a portion of recent progress in tumor and intracellular microenvironment responsive block copolymer assemblies and their applications in anticancer drug delivery and triggered release and enhanced imaging sensitivity. The outlook on future developments is also discussed. We hope that this review can stimulate more revolutionary ideas and novel concepts and meet the significant interest to diverse readers.
Highlights
With the increasing numbers of cancerous types and patients, cancer diagnosis and therapy have received a growing attention of chemists and biologists
The materials that respond to physiological relevant concentrations within micromolar or nanomolar regime are still lag behind requirement
The common feature of the above mentioned examples is that all the selective and controlled modulation processes were based on the stimuli-responsiveness of polymeric building blocks, and the accumulation in tumor sites is assisted by either passive or active targeting
Summary
With the increasing numbers of cancerous types and patients, cancer diagnosis and therapy have received a growing attention of chemists and biologists. The new kind of biological drugs such as proteins, antibodies, and nucleic acids, may be deactivated or degraded during blood circulation before they get to the target sites [5,6] These undesired side effects largely decreased the therapeutic efficacy and outcome, and the possible multidrug resistance to certain types of cancer cells might further decrease the therapeutic efficacy more or less. Nanocarriers for active targeting need to be modified with affinity ligands, such as functional organic molecules, carbohydrates, peptides, antibodies, and aptamers, which can selectively recognize and bind to specific tissues, cells, or organelles with complementary receptors or antigens [21,22] It is very important for polymer based delivery systems that the intracellular uptake efficiency can be largely promoted via specific ligand-receptor interactions, resulting in subsequent high-efficiency working within the intracellular microenvironment. We hope this review will be suitable for diverse readers in the field of chemical, biological, and medical science
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