Enzyme-Responsive Materials as Carriers for Improving Photodynamic Therapy

Recent progress of 4D printing in cancer therapeutics studies

Cancer is a critical cause of global human death. Not only are complex approaches to cancer prognosis, accurate diagnosis, and efficient therapeutics concerned, but post-treatments like postsurgical or chemotherapeutical effects are also followed up. The four-dimensional (4D) printing technique has gained attention for its potential applications in cancer therapeutics. It is the next generation of the three-dimensional (3D) printing technique, which facilitates the advanced fabrication of dynamic constructs like programmable shapes, controllable locomotion, and on-demand functions. As is well-known, it is still in the initial stage of cancer applications and requires the insight study of 4D printing. Herein, we present the first effort to report on 4D printing technology in cancer therapeutics. This review will illustrate the mechanisms used to induce the dynamic constructs of 4D printing in cancer management. The recent potential applications of 4D printing in cancer therapeutics will be further detailed, and future perspectives and conclusions will finally be proposed.

Biomaterials releasing drug responsively to promote wound healing via regulation of pathological microenvironment

Wound healing is characterized by complex, orchestrated, spatiotemporal dynamic processes. Recent findings demonstrated suitable local microenvironments were necessities for wound healing. Wound microenvironments include various biological, biochemical and physical factors, which are produced and regulated by endogenous biomediators, exogenous drugs, and external environment. Successful drug delivery to wound is complicated, and need to overcome the destroyed blood supply, persistent inflammation and enzymes, spatiotemporal requirements of special supplements, and easy deactivation of drugs. Triggered by various factors from wound microenvironment itself or external elements, stimuli-responsive biomaterials have tremendous advantages of precise drug delivery and release. Here, we discuss recent advances of stimuli-responsive biomaterials to regulate local microenvironments during wound healing, emphasizing on the design and application of different biomaterials which respond to wound biological/biochemical microenvironments (ROS, pH, enzymes, glucose and glutathione), physical microenvironments (mechanical force, temperature, light, ultrasound, magnetic and electric field), and the combination modes. Moreover, several novel promising drug carriers (microbiota, metal-organic frameworks and microneedles) are also discussed.

Intracellular and extracellular enzymatic responsive micelle for intelligent therapy of cancer

Recently, the incidence of cancer keeps increasing, seriously endangers human health, and has evolved into the main culprit of human death. Conventional chemotherapeutic drugs, such as paclitaxel and doxorubicin (DOX), have some disadvantages, including low therapeutic effect, poor water solubility, high toxic side effects, short blood circulation time in the body, and so on. To improve the anti-tumor effect of the drug in vivo and reduce its side effects on the body, researchers have designed and developed a variety of responsive nanocarriers. In this work, we synthesized D-α-tocopherol polyethylene glycol 3350 succinate (TPGS₃₃₅₀)-Gly-Pro-Leu-Gly-Val-Arg (GPLGVR)-DOX (TPD) prodrugs in response to extracellular enzymes of matrix metalloproteinase (MMP-9) in the tumor microenvironment and FA-Asp-Glu-Val-Asp (DEVD)-DOX (FPD) prodrugs responsive to intracellular enzymes of caspase-3. Then, intracellular and extracellular enzyme-responsive TPD&FPD micelles with DOX (TPD&FPD&D) were successfully prepared through dialysis method. The outer layer of TPGS3350 can prolong the blood circulation time of micelles in vivo, followed by accumulation of micelles at tumor tissue through enhanced permeability and retention (EPR) effect. The peptide of GPLGVR can be cleaved by MMP-9 enzymes to remove the outer layer of TPGS3350, exposing the targeting molecule of folate, and then the micelles are engulfed by tumor cells through folate receptor-mediated endocytosis. After entering the tumor cells, the free DOX loaded in the micelles is released, which induces tumor cell apoptosis to activate caspase-3 in the cells, cutting the peptide DEVD to accelerate the intracellular release of the DOX, which further enhances cytotoxicity to improve antitumor effect.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material () is available in the online version of this article at 10.1007/s12274-022-4967-1.