CD44-mediated tumor homing of hyaluronic acid nanogels for hypoxia-activated photodynamic therapy against tumor.

In this study, unique hypoxia-activated hyaluronic acid nanogels (HANGs) were reported for CD44-targeted delivery of photosensitizers (chlorin e6, Ce6) for diagnostic imaging and photodynamic therapy (PDT) of cancers. Through the use of a hypoxia-responsive cross-linker (AZO-CDI), the HANGs were prepared by chemically cross-linking primary amine groups-functionalized hyaluronic acid (HA). Under normoxic condition, fluorescence of Ce6 conjugated on the HANGs was highly quenched, and level of reactive oxygen species (ROS) generated from the HANGs was rather low after laser irradiation. However, under hypoxic condition, the HANGs underwent rapid disassociation, and fluorescence of Ce6 conjugated on the HANGs was recovered, triggering high-level singlet oxygen generation after laser irradiation. Due to the presence of HA, the HANGs showed much higher cellular uptake by CD44-positive cancer cells (A549 cells) than that by CD44-negative cancer cells (HepG2 cells). In addition, the HANGs could generate higher level of ROS in A549 cells because of improved cancer cell uptake. This excellent tumor-targeting and singlet oxygen-generating ability of the HANGs was favorable to hypoxia-activated PDT of CD44-positive cancers with significant inhibition of tumor growth within the whole treatment period. Taken together, the HANGs are safe and effective tools in treating CD44-positive cancers.

CD44-Targeted and Enzyme-Responsive Photo-Cross-Linked Nanogels with Enhanced Stability for In Vivo Protein Delivery.

One of the biggest challenges of the protein delivery system is to realize stable and high protein encapsulation efficiency in blood circulation and rapid release of protein in the targeted tumor cells. To overcome these hurdles, we fabricated enzyme-responsive photo-cross-linked nanogels (EPNGs) through UV-triggered chemical cross-linking of cinnamyloxy groups in the side chain of PEGylation hyaluronic acid (HA) for CD44-targeted transport of cytochrome c (CC). The EPNGs showed high loading efficiency and excellent stability in different biological media. Notably, CC leakage effectively suppressed under physiological conditions but accelerated release in the presence of hyaluronidase, an overexpressed enzyme in tumor cells. Moreover, thiazolylblue tetrazolium bromide (MTT) results indicated that the vacant EPNGs showed excellent nontoxicity, while CC-loaded EPNGs exhibited higher killing efficiency to CD44-positive A549 cells than to CD44-negative HepG2 cells and free CC. Confocal images confirmed that CC-loaded EPNGs could effectively be internalized by CD44-mediated endocytosis pathway and rapidly escape from the endo/lysosomal compartment. Human lung tumor-bearing mice imaging assays further revealed that CC-loaded EPNGs actively target tumor locations. Remarkably, CC-loaded EPNGs also exhibited enhanced antitumor activity with negligible systemic toxicity. These results implied that these EPNGs have appeared as stable and promising nanocarriers for tumor-targeting protein delivery.

A pH-activated charge convertible quantum dot as a novel nanocarrier for targeted protein delivery and real-time cancer cell imaging.

The rapid developments of nanocarriers based on quantum dots (QDs) have been confirmed to show substantial promise for drug delivery and bioimaging. However, optimal QDs-based nanocarriers still need to have their controlled behavior in vitro and in vivo and decrease heavy metal-associated cytotoxicity. Herein, a pH-activated charge convertible QD-based nanocarrier was fabricated by capping multifunctional polypeptide ligands (mPEG-block-poly(ethylenediamine-dihydrolipoic acid-2,3-dimethylmaleic anhydride)-L-glutamate, PEG-P(ED-DLA-DMA)LG) onto the surface of core/multishell CdSe@ZnS/ZnS QD by means of a ligand exchange strategy, followed by uploading of cytochrome C (CC) (CC-loaded QD-PEG-P(ED-DLA-DMA)LG) via electrostatic interactions, in which QDs that were water-soluble and protein-loading were perfectly integrated. That is, the CC-loaded QD-PEG-P(ED-DLA-DMA)LG inherited excellent fluorescence properties from CdSe@ZnS/ZnS QD for real-time imaging, as well as tumor-microenvironment sensitivities from PEG-P(ED-DLA-DMA)LG for enhanced cellular uptake and CC release. Experimental results verified that the QD-PEG-P(ED-DLA-DMA)LG showed enhanced internalization, rapid endo/lysosomal escape, and supplied legible real-time imaging for lung carcinoma cells. Furthermore, pH-triggered charge-convertible ability enabled the QD-PEG-P(ED-DLA-DMA)LG-CC to effectively kill cancer cells better than did the control groups. Hence, constructing smart nanocomposites by facile ligand-exchange strategy is beneficial to QD-based nanocarrier for tumor-targeting cancer therapy.

Intracellular delivery of cytochrome C using hypoxia-responsive polypeptide micelles for efficient cancer therapy.

To begin with, it is important to note that biodegradable polypeptides have been extensively applied as drug delivery carriers due to their excellent bioavailability, neglectful toxicity, good encapsulation and controlled release. Thus, a biodegradable and hypoxia-responsive polypeptide is a benefit when synthesized for the intracellular delivery of cytochrome c (CC). In its most positive context, this amphiphilic polypeptide can self-assemble into core/shell-structured micelles and encapsulate CC in their hydrophobic cores. Owing to the presence of hypoxia-responsive chemical bonds, the CC-loaded polymeric micelles (PMs) can potentially target hypoxic tissues (such as tumors) and release the proteins inside the cancer cells. For this reason, these PMs exhibit high protein loading content and efficiency and remain stable in several different kinds of cell culture media under normoxic condition. Moreover, the confocal microscopy indicates that CC-loaded PMs could be effectively uptaken by cancer cells and accelerate endo/lysosomal escape. Most importantly, the CC-loaded PMs show great killing effect to HepG2 liver cancer cells under hypoxic condition, which makes this nano-platform a promising candidate for use with efficient cancer therapy.