Yanjuan Wu

PEGylated Click Polypeptides Synthesized by Copper-Free Microwave-Assisted Thermal Click Polymerization for Selective Endotoxin Removal from Protein Solutions

PEGylated click polypeptides (PEG-CPs) containing α-amino side groups as well as PEG segments are designed for selective endotoxin removal from protein solutions. The PEG-CPs are synthesized via copper-free thermal click copolymerization from aspartic (or glutamic) acid-based dialkyne and diazide monomers (containing free amino side groups) and alkyne-terminated mPEGs or dialkyne-terminated PEGs. Microwave-assisting technology is introduced into thermal click chemistry to improve the reaction efficiency. The monomers and polymers are fully characterized using NMR, XPS, and MALDI-TOF MS. After immobilizing the PEGylated click polypeptides onto polystyrene microspheres, the adsorbents exhibit good endotoxin removal selectivity from BSA solutions.

Facile preparation of core cross-linked micelles from catechol-containing amphiphilic triblock copolymer

Efficient delivery of anti-cancer drugs into tumor cells for enhancing the intracellular drug concentration is a major challenge for cancer therapy due to the instability of drug-loading vehicle. In this report, we developed a simple method to stabilize the nanostructure of micelles only by bubbling air to crosslink the outer layer of the micelle core. Dopamine was conjugated to a biodegradable triblock copolymer monomethoxy poly(ethylene glycol)-b-poly(2-methyl-2-carboxyl-propylene carbonate)-b-poly(L-lactide) (mPEG-b-PMCC-b-PLA) to obtain dopamine grafted copolymer mPEG-b-P(MCC-g-dopamine)-b-PLA. After self-assembly, the core cross-linked micelles were then prepared by the oxidative self-polymerization of dopamine in the middle hydrophobic phase of the micelles. The cross-linked micelles had smaller sizes and narrower particle size distributions than their uncross-linked precursors. The improved stability was confirmed by critical micelle concentration (CMC) experiments and 1H NMR spectra. The kinetics and processes of oxidative cross-linking of micelles under air flux were monitored by UV-Vis spectroscopy and transmission electron microscopy (TEM). These core cross-linked micelles were able to load doxorubicin (DOX) with superior loading capacity of up to 19.5% (w/w, drug/micelle) with high drug loading efficiency (97.5%). Compared with the uncross-linked ones, drug release efficacy from the cross-linked micelles extremely decreased at pH 7.4. However, a properly sustained release occurred at pH 5.0, which is very favorable for drug delivery in tumor cells. The DOX-loaded micelles had similar cytotoxicity as the free drug and could be effectively internalized into MDA-MB-231 cells. This controllable and convenient approach for preparing core cross-linked micelles will have a pragmatic future in stabilizing the architecture of nanocarriers for drug delivery.

Double pH-responsive supramolecular copolymer micelles based on the complementary multiple hydrogen bonds of nucleobases and acetalated dextran for drug delivery†

A double pH-responsive supramolecular copolymer micelle was successfully developed, which was based on complementary multiple hydrogen bonds of nucleobases and acetalated dextran. The thymine-terminated poly(ethylene glycol) (T-PEG-T) and adenine-terminated acetalated dextran (AcDEX-A) were synthesized and used to construct supramolecular amphiphilic triblock copolymer AcDEX-A:T-PEG-T:A-AcDEX, which could be further self-assembled into supramolecular micelles in water. These micelles were stable at pH 7.4, but disruptive at pH 5.0 due to the double pH-sensitivity of hydrogen bonds within the copolymer backbones and the hydrolysis of the acetalated dextran. The hydroxyl coverage of Ac-DEX had an important effect on the critical micelle concentration (CMC) and particle size of AcDEX-A:T-PEG-T:A-AcDEX micelles, which were observed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). In addition, turbidometry was utilized to evaluate the effect of pH-responsivity of AcDEX-A:T-PEG-T:A-AcDEX micelles and these supramolecular micelles were completely decomposed at pH 5.0. Cytotoxicity evaluation showed good biocompatibility of these micelles, and doxorubicin (DOX) was encapsulated into supramolecular micelles as a model drug. The in vitro drug release profile showed that the DOX release speed at pH 5.0 could be adjusted by changing the hydroxyl coverage of Ac-DEX. Meanwhile, DOX-loaded supramolecular micelles could be efficiently internalized into cancer cells and showed similar inhibition of proliferation of the Hela cell as free DOX. This work provided a new method for enabling a rapid intracellular release of drugs by using double pH-sensitive hydrogen bonds and acetalated dextran, which would have the potential to be applied in controlled drug delivery.

Novel hydroxyl-containing reduction-responsive pseudo-poly(aminoacid) via click polymerization as an efficient drug carrier

A novel biodegradable pseudo-poly(aminoacid) copolymer (mPEG–HRSCP–mPEG) was produced via a mechanism of step polymerization through Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) (click polymerization) using dialkyned-cystine and diazide monomers. The disulfide and hydroxyl groups were repeatedly arranged in the polymer backbone. The introduced hydroxyl groups could not only adjust the hydrophilicity of the amphiphilic polymer, but also improve the DOX loading efficiency and solubility. Compared with the unmodified one, the polymer containing hydroxyl groups has increased hydrophilicity with a larger critical aggregation concentration (CAC) value, lower water contact angle, higher drug loading content and drug loading efficiency. The pH and reduction sensitivities of this drug delivery system (DDS) were investigated using Dynamic Light Scattering (DLS) to monitor the changes of average diameters. DOX was loaded as a model drug and in vitro release experiments demonstrated that DOX release was accelerated by an addition of 10 mM glutathione (GSH) or under acidic conditions rather than under physiological conditions. Our study on in vitro anticancer efficiency showed that DOX-loaded nanoparticles had a higher cytotoxicity towards GSH pretreated HeLa cells. These newly designed copolymer nanoparticles can be used as novel and impactful pH and reduction dual-responsive nanocarriers for intelligent DOX delivery.

Pt(IV) prodrug-backboned micelle and DCA loaded nanofibers for enhanced local cancer treatment

Drug-loaded nanocarriers, especially polymeric micelles, have attracted much attention in recent years, but their application is still limited due to their systemic toxicity and unsatisfactory tumor delivery efficiency through intravenous administration. In this study, we demonstrated an implantable prodrug micelle/small drug molecule co-loaded nanofiber strategy for enhanced local cancer treatment. A reduction-responsive Pt(iv) prodrug-backboned micelle, as a prodrug of bioactive Pt(ii), and DCA were co-electrospun into poly(vinyl alcohol) (PVA) nanofibers. The prepared Pt(iv) prodrug-backboned micelle/DCA fibers exerted a synergistic effect on cancer cells. In contrast to systemic administration of chemotherapeutic agents, this implantable device exhibited enhanced anti-cancer efficacy with lower systemic toxicity against advanced cervical cancer in vivo. This work provides a facile, efficient and safe prospect of using a prodrug micelle and small molecular drug co-loaded electrospun device for localized and advanced cancer therapy.

Dual-Sensitive Charge-Conversional Polymeric Prodrug for Efficient Codelivery of Demethylcantharidin and Doxorubicin

A tumor is a complicated system, and tumor cells are typically heterogeneous in many aspects. Polymeric drug delivery nanocarriers sensitive to a single type of biosignals may not release cargos effectively in all tumor cells, leading to low therapeutic efficacy. To address the challenges, here, we demonstrated a pH/reduction dual-sensitive charge-conversional polymeric prodrug strategy for efficient codelivery. Reduction-sensitive disulfide group and acid-labile anticancer drug (demethylcantharidin, DMC)-conjugated β-carboxylic amide group were repeatedly and regularly introduced into copolymer chain simultaneously via facile CuAAC click polymerization. The obtained multifunctional polymeric prodrug P(DMC), mPEG-b-poly(disulfide-alt-demethylcantharidin)-b-mPEG was further utilized for DOX encapsulation. Under tumor tissue/cell microenvironments (pH 6.5 and 10 mM GSH), the DOX-loaded polymeric prodrug nanoparticles (P(DMC)@DOX NPs) performed surface negative-to-positive charge conversion and accelerated/sufficient release of DMC and DOX. The remarkably enhanced cellular internalization and cytotoxicity in vitro, especially against DOX-resistant SMMC-7721 cells, were demonstrated. P(DMC)@DOX NPs in vivo also exhibited higher tumor accumulation and improved antitumor efficiency compared to P(SA)@DOX NPs with one drug and without charge-conversion ability. The desired multifunctional polymeric prodrug strategy brings a new opportunity for cancer chemotherapy.

Novel multi-sensitive pseudo-poly(amino acid) for effective intracellular drug delivery

Novel intracellular pH, glutathione (GSH) and reactive oxygen species (ROS)-responsive nanoparticles were obtained using mPEG2k-block-redox dual sensitive chain-block-mPEG2k (PRDSP) which was prepared by Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) click polymerization. The disulfide bond, peroxalate ester and triazole units were regularly and repeatedly arranged in the hydrophobic blocks. The disulfide bond was GSH-sensitive and the peroxalate ester structure could be disrupted by acid and hydrogen peroxide. In addition, the triazole units are capable of forming pH-responsive hydrogen bonds. Dynamic Light Scattering (DLS) and transmission electron microscopy (TEM) were used to investigate the pH, GSH and ROS sensitivity of the PRDSP nanoparticles (NPs). The results indicated that the average diameter, size distribution and morphology greatly changed upon adding GSH/H2O2 or modulating the pH. As the preloaded model anticancer drug, doxorubicin (DOX) was quickly released from DOX-loaded PRDSP (PRDSP@DOX) NPs by addition of 10 mM glutathione (GSH), or 10 mM H2O2 or under acidic conditions rather than under physiological conditions. Confocal laser scanning microscopy (CLSM) and flow cytometric analyses revealed that PRDSP@DOX could effectively deliver DOX into the cytoplasm and nucleus of cells. Therefore, PRDSP NPs may be a promising redox heterogeneity-sensitive carrier for efficient and controlled anticancer drug release.

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.