Wei-Hai Chen

Multifunctional Envelope-Type Mesoporous Silica Nanoparticles for Tumor-Triggered Targeting Drug Delivery

A novel type of cellular-uptake-shielding multifunctional envelope-type mesoporous silica nanoparticle (MEMSN) was designed for tumor-triggered targeting drug delivery to cancerous cells. β-Cyclodextrin (β-CD) was anchored on the surface of mesoporous silica nanoparticles via disulfide linking for glutathione-induced intracellular drug release. Then a peptide sequence containing Arg-Gly-Asp (RGD) motif and matrix metalloproteinase (MMP) substrate peptide Pro-Leu-Gly-Val-Arg (PLGVR) was introduced onto the surface of the nanoparticles via host-guest interaction. To protect the targeting ligand and prevent the nanoparticles from being uptaken by normal cells, the nanoparticles were further decorated with poly(aspartic acid) (PASP) to obtain MEMSN. In vitro study demonstrated that MEMSN was shielded against normal cells. After reaching the tumor cells, the targeting property could be switched on by removing the PASP protection layer via hydrolyzation of PLGVR at the MMP-rich tumor cells, which enabled the easy uptake of drug-loaded nanoparticles by tumor cells and subsequent glutathione-induced drug release intracellularly.

Multifunctional Enveloped Mesoporous Silica Nanoparticles for Subcellular Co-delivery of Drug and Therapeutic Peptide

A multifunctional enveloped nanodevice based on mesoporous silica nanoparticle (MSN) was delicately designed for subcellular co-delivery of drug and therapeutic peptide to tumor cells. Mesoporous silica MCM-41 nanoparticles were used as the core for loading antineoplastic drug topotecan (TPT). The surface of nanoparticles was decorated with mitochondria-targeted therapeutic agent (Tpep) containing triphenylphosphonium (TPP) and antibiotic peptide (KLAKLAK)2 via disulfide linkage, followed by coating with a charge reversal polyanion poly(ethylene glycol)-blocked-2,3-dimethylmaleic anhydride-modified poly(L-lysine) (PEG-PLL(DMA)) via electrostatic interaction. It was found that the outer shielding layer could be removed at acidic tumor microenvironment due to the degradation of DMA blocks and the cellular uptake was significantly enhanced by the formation of cationic nanoparticles. After endocytosis, due to the cleavage of disulfide bonds in the presence of intracellular glutathione (GSH), pharmacological agents (Tpep and TPT) could be released from the nanoparticles and subsequently induce specific damage of tumor cell mitochondria and nucleus respectively with remarkable synergistic antitumor effect.

Design of a Cellular‐Uptake‐Shielding “Plug and Play” Template for Photo Controllable Drug Release

Polymeric drug delivery systems have been widely used for controlled drug release. [ 1–5 ] To enhance the antitumor effi ciency of antineoplastic drugs, a traditional way is to introduce a target ligand into the polymer to promote the drug endocytosis of tumor cells. [ 6–11 ] Furthermore, stimulus-responsive polymers such as pH-sensitive, light-sensitive, or temperaturesensitive polymers have been also used to trigger the drug release at tumor sites to improve the cure effect. [ 12–17 ] However, both methods cannot inhibit normal cells endocytosing antineoplastic drugs and this limitation might cause fatal damage to normal tissues. New drug delivery systems that can evade normal tissues will be critically important to reduce the side effect of antineoplastic drug in normal tissues. Here, we designed a novel light-responsive “plug and play” (PnP) polyanionic template as drug delivery system, which can inhibit the endocytosis of antineoplastic drug for normal tissues. The drug loaded on the polyanionic template is repelled by cells and will not be uptaken by normal tissues during blood circulation, whereas upon irradiation of UV light at the target site, such as tumor tissues, the loaded drug can be released quickly from the template and thereafter be endocytosed by tumor cells. Importantly, as a PnP polymeric template, antineoplastic drug and additional functional moieties such as target ligand can be simultaneously loaded and unloaded onto the template. The polyanionic template consists of polyacrylic acid (PAA) and azobenzene (Azo). The loading and unloading process is driven by the photo-switchable host-guest interaction between α -cyclodextrin ( α -CD) and Azo. Azobenzene, having trans and cis forms, can be reversibly transformed to each other upon photo-irradiation. [ 18–21 ] Driven by hydrophobic and van der Waals interactions, trans -azobenzene could be well recognized by α -CD. On the other hand, once trans -azobenzene transforms to cis form, α -CD cannot include the bulky cis -azobenzene anymore because of the mismatch between the host and guest. [ 22–27 ]

Synergistic gene and drug tumor therapy using a chimeric peptide

Co-delivery of gene and drug for synergistic therapy has provided a promising strategy to cure devastating diseases. Here, an amphiphilic chimeric peptide (Fmoc)2KH7-TAT with pH-responsibility for gene and drug delivery was designed and fabricated. As a drug carrier, the micelles self-assembled from the peptide exhibited a much faster doxorubicin (DOX) release rate at pH 5.0 than that at pH 7.4. As a non-viral gene vector, (Fmoc)(2)KH(7)-TAT peptide could satisfactorily mediate transfection of pGL-3 reporter plasmid with or without the existence of serum in both 293T and HeLa cell-lines. Besides, the endosome escape capability of peptide/DNA complexes was investigated by confocal laser scanning microscopy (CLSM). To evaluate the co-delivery efficiency and the synergistic anti-tumor effect of gene and drug, p53 plasmid and DOX were simultaneously loaded in the peptide micelles to form micelleplexes during the self-assembly of the peptide. Cellular uptake and intracellular delivery of gene and drug were studied by CLSM and flow cytometry respectively. And p53 protein expression was determined via Western blot analysis. The in vitro cytotoxicity and in vivo tumor inhibition effect were also studied. Results suggest that the co-delivery of gene and drug from peptide micelles resulted in effective cell growth inhibition in vitro and significant tumor growth restraining in vivo. The chimeric peptide-based gene and drug co-delivery system will find great potential for tumor therapy.

Dual-Targeting Pro-apoptotic Peptide for Programmed Cancer Cell Death via Specific Mitochondria Damage

Mitochondria are vital organelles to eukaryotic cells. Damage to mitochondria will cause irreversible cell death or apoptosis. In this report, we aim at programmed cancer cell death via specific mitochondrial damage. Herein, a functionalized pro-apoptotic peptide demonstrates a dual-targeting capability using folic acid (FA) (targeting agent I) and triphenylphosphonium (TPP) cation (targeting agent II). FA is a cancer-targeting agent, which can increase the cellular uptake of the pro-apoptotic peptide via receptor-mediated endocytosis. And the TPP cation is the mitochondrial targeting agent, which specifically delivers the pro-apoptotic peptide to its particular subcellular mitochondria after internalized by cancer cells. Then the pro-apoptotic peptide accumulates in mitochondria and causes its serious damage. This dual-targeting strategy has the potential to effectively transport the pro-apoptotic peptide to targeted cancer cell mitochondria, inducing mitochondrial dysfunction and triggering the mitochondria-dependent apoptosis to efficiently eliminate cancer cells.

Design of a Photoswitchable Hollow Microcapsular Drug Delivery System by Using a Supramolecular Drug-Loading Approach

In this study, photoswitchable microcapsules were fabricated based on host-guest interactions between α-cyclodextrin (α-CD) and azobenzene (Azo). Carboxymethyl dextran-graft-α-CD (CMD-g-α-CD) and poly(acrylic acid) N-aminododecane p-azobenzeneaminosuccinic acid (PAA-C(12)-Azo) were assembled layer by layer on CaCO(3) particles. α-CD-rhodamine B (α-CD-RhB), used as a model drug, was loaded on PAA-C(12)-Azo layers by host-guest interaction. After removal of CaCO(3) particles by ethylenediaminetetraacetic acid (EDTA), hollow microcapsules loaded with α-CD-RhB were obtained. Since the interactions between α-CD and Azo were photosensitive, the capsules could be dissociated with the irradiation of UV light, followed by the release of the model drug, α-CD-RhB. Compared with traditional drug-loading approaches such as chemical bonding and physical adsorption, our supramolecular drug-loading system has a facile loading process, ideal bonding strength, and photoswitchable behavior. These photosensitive microcapsules exhibit great potential in biomedical applications.

Charge-reversal plug gate nanovalves on peptide-functionalized mesoporous silica nanoparticles for targeted drug delivery

To develop a smart nanovalve on mesoporous silica nanoparticles (MSNs) for biomedical applications, a new type of peptide-functionalized MSN with a plug-gate nanovalve (PGN) was designed for targeted drug release in cancer cells. The outer shell of MSN was functionalized with K8 peptide (octa-lysine sequence) by click chemistry, followed by reacting with citraconic anhydride viaα,β-unsaturated bond to prepare negatively charged MSN-K8(Cit). Subsequently, a cationic K8(RGD)2 peptide containing two Arg-Gly-Asp (RGD) sequences for targeting was introduced via electrostatic interaction to the negatively charged surface of MSN-K8(Cit) to form PGN. It was found that, at pH 5.0 (simulating the endo/lysosomal environment), the surface charge of MSN-K8(Cit) could convert from -41 mV to +19 mV due to the hydrolysis of the acid-labile amides in the acidic condition, implying the subsequent electrostatic repulsion to induce opening of the nanovalves and release of anticancer drug, DOX. According to the drug release studies, 79% of DOX was released within 48 h at pH 5.0, while much less DOX was released at pH 6.5 and 7.4. Furthermore, in vitro cellular experiments confirmed that the drug delivery system had enhanced cellular association and cell inhibition effect on αvβ3-positive U87 MG cancerous cells.

One-Pot Construction of Functional Mesoporous Silica Nanoparticles for the Tumor-Acidity-Activated Synergistic Chemotherapy of Glioblastoma

Mesoporous silica nanoparticles (MSNs) have proved to be an effective carrier for controlled drug release and can be functionalized easily for use as stimuli-responsive vehicles. Here, a novel intelligent drug-delivery system (DDS), camptothecin (CPT)-loaded and doxorubicin (DOX)-conjugated MSN (CPT@MSN-hyd-DOX), is reported via a facile one-pot preparation for use in synergistic chemotherapy of glioblastoma. DOX was conjugated to MSNs via acid-labile hydrazone bonds, and CPT was loaded in the pores of the MSNs. At pH 6.5 (analogous to the pH in tumor tissues), a fast DOX release was observed that was attributed to the hydrolysis of the hydrazone bonds. In addition, a further burst release of DOX was found at pH 5.0 (analogous to the pH in lyso/endosomes of tumor cells), leading to a strong synergistic effect. In all, CPT and DOX could be delivered simultaneously into tumor cells, and this intelligent DDS has great potential for tumor-trigged drug release for use in the synergistic chemotherapy of tumors.

A pH-responsive drug nanovehicle constructed by reversible attachment of cholesterol to PEGylated poly(l-lysine) via catechol-boronic acid ester formation.

The present work reports the construction of a drug delivery nanovehicle via a pH-sensitive assembly strategy for improved cellular internalization and intracellular drug liberation. Through spontaneous formation of boronate linkage in physiological conditions, phenylboronic acid-modified cholesterol was able to attach onto catechol-pending methoxypoly(ethylene glycol)-block-poly(l-lysine). This comb-type polymer can self-organize into a micellar nanoconstruction that is able to effectively encapsulate poorly water-soluble agents. The blank micelles exhibited negligible in vitro cytotoxicity, yet doxorubicin (DOX)-loaded micelles could effectively induce cell death at a level comparable to free DOX. Owing to the acid-labile feature of the boronate linkage, a reduction in environmental pH from pH 7.4 to 5.0 could trigger the dissociation of the nanoconstruction, which in turn could accelerate the liberation of entrapped drugs. Importantly, the blockage of endosomal acidification in HeLa cells by NH4Cl treatment significantly decreased the nuclear uptake efficiency and cell-killing effect mediated by the DOX-loaded nanoassembly, suggesting that acid-triggered destruction of the nanoconstruction is of significant importance in enhanced drug efficacy. Moreover, confocal fluorescence microscopy and flow cytometry assay revealed the effective internalization of the nanoassemblies, and their cellular uptake exhibited a cholesterol dose-dependent profile, indicating the contribution of introduced cholesterol functionality to the transmembrane process of the nanoassembly.

In situ recognition of cell-surface glycans and targeted imaging of cancer cells

Fluorescent sensors capable of recognizing cancer-associated glycans, such as sialyl Lewis X (sLex) tetrasaccharide, have great potential for cancer diagnosis and therapy. Studies on water-soluble and biocompatible sensors for in situ recognition of cancer-associated glycans in live cells and targeted imaging of cancer cells are very limited at present. Here we report boronic acid-functionalized peptide-based fluorescent sensors (BPFSs) for in situ recognition and differentiation of cancer-associated glycans, as well as targeted imaging of cancer cells. By screening BPFSs with different structures, it was demonstrated that BPFS1 with a FRGDF peptide could recognize cell-surface glycan of sLex with high specificity and thereafter fluorescently label and discriminate cancer cells through the cooperation with the specific recognition between RGD and integrins. The newly developed peptide-based sensor will find great potential as a fluorescent probe for cancer diagnosis.