Shasha He

Single-Stimulus Dual-Drug Sensitive Nanoplatform for Enhanced Photoactivated Therapy

Photoactivated therapy has become a complementary and attractive modality for traditional cancer treatment. Herein, we demonstrated a novel single-stimulus dual-drug sensitive nanoplatform, Cur-loaded Dex-Pt(N3) nanoparticles (Cur@DPNs) for enhanced photoactivated therapy. The developed Cur@DPNs could be photoactivated by UVA light to simultaneously generate instant reactive oxygen species from Cur for fast photodynamic therapy and release lasting Pt(II) from Pt(N3) for long-acting photochemotherapy. Compared with small free drugs and individual photoactivated therapy, Cur@DPNs exhibited enhanced photoactivated cytotoxicity and in vivo antitumor efficacy with low systemic toxicity accompanied. Therefore, the single-stimulus dual-drug sensitive nanoplatform is convinced to be a promising strategy for multidrug delivery, site-selective and combinational photoactivated therapy in the near future.

A dextran–platinum(IV) conjugate as a reduction-responsive carrier for triggered drug release

Reduction-responsive nano-carriers have been confirmed to be promising for intracellular drug delivery. To develop multifunctional polymer-based drug delivery system, a novel dextran-Pt(iv) conjugate was synthesized by conjugating Pt(iv) to the side chains of the hydrophilic dextran and used for doxorubicin (DOX) delivery. Pt(iv) conjugation could change the hydrophilicity of dextran, leading to the self-assembly of dextran-Pt(iv) conjugates with different morphologies. Pt(iv) segments served as the key components in assembly formation and as the antitumor prodrug. Under a reductive environment, Pt(iv) was found to be reduced to its active Pt(ii) form and cleaved from dextran, shifting the hydrophilic-hydrophobic balance of the dextran-Pt(iv) conjugate. The collapse of the assembly structure due to the partial or complete recovery of the hydrophilicity of dextran led to triggered release of DOX. The DOX-loaded dextran-Pt(iv) conjugate obtained by combining the released hydrophobic DOX and recovered hydrophilic Pt(ii), was found to be very effective as an antitumor agent as demonstrated in in vitro cytotoxicity evaluations. This DOX-loaded dextran-Pt(iv) conjugate system provided a new strategy to trigger the release of hydrophobic and hydrophilic drugs at the same time via single reduction-responsive control to provide an enhanced anti-tumor effect.

Asymmetric copolymer vesicles to serve as a hemoglobin vector for ischemia therapy

Self-aggregated vesicles have been considered to be promising candidates for hemoglobin-based oxygen carriers. Here, amphiphilic hetero-triblock copolymers are designed and synthesized with the capacity to self-assemble into polymer vesicles (polymersomes). Conceivably, vesicles are formed with asymmetric membranes, which achieve enhanced encapsulation efficiency of hemoglobin (Hb) beyond the diblock counterpart. Furthermore, hemoglobin-loaded vesicles (HbV) are fabricated with high Hb content and submicron particle sizes. The gas-binding capability, oxygen affinity and methemoglobin (metHb) level of the HbV dispersions are all comparable to the natural erythrocytes. In vitro HbV stability studies further reveal that the encapsulation of Hb within vesicles can greatly avoid the existence of free Hb and shows no interference with cells, especially for blood components. To evaluate the efficacy on ischemia reperfusion, HbV suspended in a plasma expander is transfused as a resuscitation fluid into an acute anemia rat model. Results demonstrate that the combined infusion of the plasma expander with HbV effectively ameliorates the lethal shock symptom and reduces short-term mortality. Concurrently, rats transfused with HbV are void of the acute tubular necrosis caused by the filtration of dissociated Hb dimers from glomeruli. We envision that the oxygen carriers derived from polymer self-assembly technology will become an alternative strategy for future development of blood substitutes.

Insight into the fabrication of polymeric particle based oxygen carriers

For the sake of protein stability and targeted application as blood substitutes, formulation customization of hemoglobin-loaded polymeric particles (HbP) was conducted via a double emulsion method. Screening of the emulsification parameters was firstly performed for the stability of Hb, and the structure and functions of recovered Hb could be well preserved via CD and UV-vis spectroscopy investigation. In the optimized conditions, Hb was loaded into the polymeric matrix formed of three material compositions. They were poly(ϵ-caprolactone)(PCL), poly(ethylene glycol)-block-poly(allyl glycidyl ether) (functionalized with mercaptopropionic acid)-block-poly(ϵ-caprolactone) (PEG-PAGE(MPA)-PCL), and the blend of the two polymers. The morphology, internal structure, in vitro leakage and hemocompatibility of the HbP products were characterized in detail, and the encapsulation mechanism was explored by the combined analysis of the encapsulation efficiency, non-specific protein adsorption and in vitro leakage studies. Results showed that the burst release effect found in homopolymers could be alleviated by use of block copolymers due to the reduced protein adsorption, and completely avoided by further cross-linking of particles through carbonyl-amino condensation reactions. The amphiphilic copolymers showed relatively high stability in blood and no interference with blood components compared with hydrophobic PCL. These results suggest that both the optimization of emulsion formation and material composition are prerequisite for stable formulations of Hb encapsulated in polymeric particles.

A polymer–(multifunctional single-drug) conjugate for combination therapy

Combination therapy based on polymer-drug conjugates is one of the exciting developments in polymeric drug delivery systems. A single polymer carrier with two or more drugs attached is advantageous because it provides a platform for synergistic agent action. To expand the concept of combination therapy using a single polymer-drug conjugate, we report a polymer-(multifunctional single-drug) conjugate strategy, in which three different drugs (platinum, azidyl radical and DMC) and two different types of therapies are rationally integrated and then conjugated to an amphiphilic block copolymer. When this polymer-(multifunctional single-drug) conjugate is internalized by cancer cells via endocytosis, the three integrated drugs are expected to be activated and execute therapeutic functions in a sequential fashion under extracellular (UVA irradiation) and intracellular (endosomes/lysosomes) environments to amplify the signals of cancer treatment, especially in cisplatin-resistant cancer cells.

Multifunctional single-drug loaded nanoparticles for enhanced cancer treatment with low toxicity in vivo

Platinum(II) complexes are used for treating over half of cancers in the clinic. However, their application is accompanied with acquired resistance and severe toxic side effects. To address these challenges, a multifunctional single drug constructed from a photo-activated oxaliplatin(IV) complex and DMC was conjugated to polymer to form multifunctional single-drug-loaded nanoparticles. When the nanoparticles are internalized by cancer cells via endocytosis, active oxaliplatin(II) can be released upon UVA irradiation to attack DNA, while DMC will be hydrolyzed subsequently from the polymer chain within the intracellular environment to block DNA repair by PP2A inhibition. The multifunctional single-drug-loaded nanoparticles exhibited enhanced anti-cancer efficacy and decreased toxicity compared to oxaliplatin(II) in vitro and in vivo. This enhanced cancer treatment strategy could have potential clinical use in the near future.

A facile way to prepare functionalized dextran nanogels for conjugation of hemoglobin

Nanogels with several special advantages have been widely applied in protein delivery. However, biocompatible and biodegradable nanogels used for hemoglobin (Hb) delivery are far less explored. Herein, we developed a facile method to prepare functionalized dextran nanogels for conjugation of Hb. In situ cross-linked and aldehyde group functionalized nanogels (FNGs) were prepared from dextran-g-succinic anhydride-g-dopamine conjugate (Dex-SA-DA) assembly by simple pH adjustion and oxidization in water. Hb was further conjugated into the swelling FNGs by Schiff base reaction under mild condition. The obtained hemoglobin-loaded nanogels (HbNGs) exhibited high stability, oxygen affinity and good hemo-compatibility, suggesting the potential for oxygen carriers. We expected that the designed functionalized nanogels with high stability and loading capacity could bring a new opportunity for protein delivery.

Dextran-platinum(IV) conjugate as drug carrier for triggered drug release

and migration targeting Notch pathway and Bcl-2. To increase the delivery efficiency of miR-34a, it is necessary to construct targeting delivery systems. Chondroitin sulfate (CS) is a natural polysaccharide with high affinity to CD44 which is over-expressed in many solid tumors [2], and thus CS could be used as a specific ligand targeting cancer cells via CD44-mediated endocytosis. Here, chondroitin sulfate was chemically conjugated to poly (amidoamine) (PAMAM) through Michael addition, and then the carrier was employed for realizing the miR-34a delivery, using CD44overexpressing tumor cells as model. The nanoparticles from PAMAMCSMA andmiR-34a were prepared with particle size and zeta-potential of 112.5 nm and +16.5 mV, respectively. In vitro endocytosis analysis indicated that miR-34a could be highly delivered to the CD44+ cells, mainly based on clathrin-dependent and CD44-mediated endocytosis. After the miR-34a delivery, obvious apoptosis was detected by flow cytometric analysis, especially high cell apoptosis ratio in p53 cells (29.61% in PC-3 and 21.19% in MIAPaca-2). Meanwhile, the upregulation of miR-34a could remarkably induce the cell cycle arrest at G1 phase. In addition, the miR-34a delivery could suppress the cell migration using in vitro transwell migration assay. Western-blot analysis showed that the miR-34a delivery could decrease the expression level of targeting genes, such as CD44 and Bcl-2, which would be favorable for improving the drug sensitivity. The nanocarrier with chondroitin sulfate as ligand could be an effective system for miR34a delivery to construct a therapeutic strategy for cancers, especially for solving the multi-drug resistance through the co-delivery of miR34a and chemotherapeutics.

Tailoring Platinum(IV) Amphiphiles for Self-Targeting All-in-One Assemblies as Precise Multimodal Theranostic Nanomedicine

Drug, targeting ligand, and imaging agent are the three essential components in a nanoparticle-based drug delivery system. However, tremendous batch-to-batch variation of composition and drug content typically accompany the current approaches of building these components together. Herein, we report the design of photoactivatable platinum(IV) (Pt(IV)) amphiphiles containing one or two hydrophilic lactose targeting ligands per hydrophobic Pt(IV) prodrug for an all-in-one precise nanomedicine. Self-assembly of these Pt(IV) amphiphiles results in either micelle or vesicle formation with a fixed Pt/targeting moiety ratio and a constantly high content of Pt. The micelles and vesicles are capable of hepatoma cell-targeting, fluorescence/Pt-based CT imaging and have shown effective anticancer efficacy under laser irradiation in vitro and in vivo. This photoactivatable, active self-targeting, and multimodal theranostic amphiphile strategy shows great potential in constructing precise nanomedicine.

A Versatile Method to Prepare Protein Nanoclusters for Drug Delivery

Nanocarriers based on natural biomaterials such as peptides and proteins have shown great advantages in the field of nanomedicine. However, the complicated preparation process and possible denaturation of proteins may limit their further applications. Herein, a novel method is developed to prepare protein nanocluster drug delivery system based on the self-aggregated property of proteins under the isoelectric point condition. The crosslinked protein nanoclusters, prepared by adding modified natural crosslinking agent polysaccharide, exhibit excellent stability and autofluorescent property in physiological conditions. Hemoglobin, a model protein, is chosen for preparation of drug-loaded nanoclusters. The as-prepared nanoclusters demonstrate a pH-responsive drug release behavior and can successfully deliver drugs into cancer cells. Moreover, this approach can be extended to various proteins, exemplifying the universal applicability of our new preparation method for protein-based nanoparticles.