Hyaluronic-Acid-Based pH-Sensitive Nanogels for Tumor-Targeted Drug Delivery

SPIONs embedded in polyamino acid nanogels to synergistically treat tumor microenvironment and breast cancer cells

The extremely complex tumor microenvironment (TME) in humans is the major responsible for the therapeutic failure in cancer nanomedicine. A new concept of disease-driven nanomedicine, henceforth named "Theranomics", which attempts to target cancer cells and TME on the whole, represents an attractive alternative. Herein, a nanomedicine able to co-deliver doxorubicin and a tumor suppressive proteolytic protein such as collagenase-2 was developed. We successfully obtained superparamagnetic nanogels (SPIONs/Doco@Col) via the intermolecular azide-alkyne Huisgen cycloaddition. We demonstrated that a local ECM degradation and remodeling in solid tumors by means of collagenase-2 could enhance tumor penetration of nanomedicines and the in situ sustained release of the drug payload throughout 3-D tumor spheroids up to the core (parenchyma), thus enabling a synergistic and efficient anticancer effect toward highly invasive breast tumors. We illustrate that SPIONs/Doxo@Col is also capable of reducing the invasivity of cancer cells.

Smart pH-Sensitive Nanogels for Controlled Release in an Acidic Environment

The encapsulation of therapeutic compounds into nanosized delivery vectors has become an important strategy to improve efficiency and reduce side effects in drug delivery applications. Here, we report the synthesis of pH-sensitive nanogels, which are based on the monomer N-[(2,2-dimethyl-1,3-dioxolane)methyl]acrylamide (DMDOMA) bearing an acid cleavable acetal group. Degradation studies revealed that these nanogels hydrolyze under acidic conditions and degrade completely, depending on the cross-linker, but are stable in physiological environment. The best performing system was further studied regarding its release kinetics using the anticancer drug doxorubicin. In vitro studies revealed a good compatibility of the unloaded nanogel and the capability of the doxorubicin loaded nanogel to mediate cytotoxic effects in a concentration and time-dependent manner with an even higher efficiency than the free drug. Based on the investigated features, the presented nanogels represent a promising and conveniently prepared alternative to existing carrier systems for drug delivery.

Phosphorylcholine-Based Stealthy Nanocapsules Decorating TPGS for Combatting Multi-Drug-Resistant Cancer

Improving the anticancer efficacy of chemotherapeutics not only demands for efficient delivery into tumor sites, but also always needs to combat the multidrug resistance of cancer. Here we attempted to conquer both these problems by decorating D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) onto a phosphorylcholine-based stealthy nanocapsule. This TPGS-decorated stealthy nanocapsule, referred as nBSA-TPGS-Dox, conjugated anticancer drug doxorubicin (Dox) through an acid-responsive benzoic-imine bond. nBSA-TPGS-Dox was demonstrated to be stable in PBS and exhibited acid-responsive Dox release behavior. In vitro results showed this nanocapsule could be efficiently uptaken by the Dox-resistant HepG2/ADR human liver cancer cells through clathrin-mediated endocytosis and greatly prevented the Dox efflux, causing much more cytotoxicity than free Dox and non-TPGS-decorated nBSA-Dox. Furthermore, nBSA-TPGS-Dox exhibited much prolonged in vivo half-life compared to conventional PEGylated nanoparticles and achieved excellent tumor accumulation. Finally, this TPGS-decorated stealthy nanocapsule performed outstanding suppression of Dox-resistant tumor, much superior than non TPGS-decorated nBSA-Dox and free Dox. Thus, this TPGS-decorated stealthy nanocapsule provides a novel powerful nanomedicine platform for combatting multi-drug-resistant cancer.

pH-sensitive prodrug conjugated polydopamine for NIR-triggered synergistic chemo-photothermal therapy

Combination of chemotherapy with photothermal therapy (PTT) demonstrate highly desirable for efficient medical treatment of tumor. At present works, camptothecin (CPT)-containing polymeric prodrug (PCPT) were fabricated by polymerization of a pH-sensitive camptothecin (CPT) prodrug monomer and MPC using reversible addition-fragmentation transfer (RAFT) strategy. The pH-sensitive polymeric prodrug was tethered onto surface of polydopamine (PDA) nanoparticles by amidation chemistry for combination of chemotherapy with photothermal therapy. Specifically, the active CPT quickly released from the multifunctional nanoparticles in acidic microenvironment ascribe to the cleavage of bifunctional silyl ether linkage. Meanwhile, the PDA could convert the near infrared (NIR) light energy into heat with high efficiency, which makes the resulted nanoparticles an effective platform for photothermal therapy. In vitro analysis confirmed that the PDA@PCPT nanoparticles could be efficiently uptaked by HeLa cells and deliver CPT into the nuclei of cancer cells. The cell viability assays indicated an evident in vitro cytotoxicity to HeLa cancer cells under 808 nm light irradiation. Significant tumor regression was also observed in the tumor-bearing mice model with the combinational therapy provided from the PDA@PCPT nanoparticles. The PDA@PCPT multifunctional system which was achieved by a facile route should be a potential candidate in the anti-cancer field due to the synergistic therapeutic effect, which is superior to any single approach.

One-Step Preparation of pH-Responsive Polymeric Nanogels as Intelligent Drug Delivery Systems for Tumor Therapy

In this work, pH-responsive polypeptide-based nanogels are reported as potential drug delivery systems. By the formation of pH-sensitive benzoic imine bonds, pH-responsive nanogels are constructed using hydrophilic methoxy poly(ethylene glycol)- b-poly[ N-[ N-(2-aminoethyl)-2-aminoethyl]-l-glutamate] (MPEG- b-PNLG) and hydrophobic terephthalaldehyde (TPA) as a cross-linker. At pH 7.4, MPEG- b-PNLG nanogels exhibit high stabilities with hydrophobic inner cores, which allow encapsulation of hydrophobic therapeutic agents. Under tumoral acidic environments (pH ∼6.4), the cleavage of benzoic imine bonds induces the destruction of MPEG- b-PNLG nanogels and leads to rapid release of their payloads. The formation and pH sensitivity of the nanogels are investigated by dynamic light scattering. These nanogels exhibit excellent stabilities in the presence of salt or against dilution. The globular morphologies of the nanogels are confirmed using transmission electron microscopy. Doxorubicin is used as a model drug to evaluate drug encapsulation and release. Finally, the anticancer activities of the drug-encapsulated nanogels are assessed in vitro.

Robust oil-core nanocapsules with hyaluronate-based shells as promising nanovehicles for lipophilic compounds

The design of nanodelivery systems has been recently considered as a solution to the major challenge in pharmaceutical research - poor bioavailability of lipophilic drugs. Nanocapsules with liquid oil cores and shells based on amphiphilic polysaccharides were developed here as robust carriers of hydrophobic active compounds. A series of modified charged hyaluronates were synthesized and used as stabilizing shells ensuring also the biocompatibility of the nanocapsules that is crucial for applications related to the delivery of lipophilic drugs in vivo. Importantly, the oil nanodroplets were found to be stably suspended in water for at least 15 months without addition of low molar mass surfactants. Moreover, their size and stability may be tuned by varying the relative content of hydrophobic and hydrophilic groups in the hyaluronate derivatives as was confirmed by dynamic light scattering and nanoparticle tracking analysis as well as electron microscopy. In vivo studies demonstrated that hyaluronate-based nanocapsules accumulated preferentially in the liver as well as in the lungs. Moreover, their accumulation was dramatically potentiated in endotoxemic mice. In vitro studies showed that the nanocapsules were taken up by liver sinusoidal endothelial cells and by mouse lung vascular endothelial cells. Importantly, the capsules were found to be nontoxic in an acute oral toxicity experiment even at a dose of 2000 mg per kg b.w. Biocompatible hyaluronate-based nanocapsules with liquid cores described herein represent a promising and tunable nanodelivery system for lipophilic active compounds via both oral and intravenous administration.