Qiuyu Qu

A Preloaded Amorphous Calcium Carbonate/Doxorubicin@Silica Nanoreactor for pH‐Responsive Delivery of an Anticancer Drug

Biomedical applications of nontoxic amorphous calcium carbonate (ACC) nanoparticles have mainly been restricted because of their aqueous instability. To improve their stability in physiological environments while retaining their pH-responsiveness, a novel nanoreactor of ACC-doxorubicin (DOX)@silica was developed for drug delivery for use in cancer therapy. As a result of its rationally engineered structure, this nanoreactor maintains a low drug leakage in physiological and lysosomal/endosomal environments, and responds specifically to pH 6.5 to release the drug. This unique ACC-DOX@silica nanoreactor releases DOX precisely in the weakly acidic microenvironment of cancer cells and results in efficient cell death, thus showing its great potential as a desirable chemotherapeutic nanosystem for cancer therapy.

Polymer-Coated Hollow Mesoporous Silica Nanoparticles for Triple-Responsive Drug Delivery.

In this study, pH, reduction and light triple-responsive nanocarriers based on hollow mesoporous silica nanoparticles (HMSNs) modified with poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA) were developed via surface-initiated atom transfer radical polymerization. Both reduction-cleavable disulfide bond and light-cleavable o-nitrobenzyl ester were used as the linkages between HMSNs and pH-sensitive PDEAEMA polymer caps. A series of characterization techniques were applied to characterize and confirm the structures of the intermediates and final nanocarriers. Doxorubicin (DOX) was easily encapsulated into the nanocarriers with a high loading capacity, and quickly released in response to the stimuli of reducing agent, acid environment or UV light irradiation. In addition, flow cytometry analysis, confocal laser scanning microscopy observations and cytotoxicity studies indicated that the nanocarriers were efficiently internalized by HeLa cancer cells, exhibiting (i) enhanced release of DOX into the cytoplasm under external UV light irradiation, (ii) better cytotoxicity against HeLa cells, and (iii) superior control over drug delivery and release. Thus, the triple-responsive nanocarriers present highly promising potentials as a drug delivery platform for cancer therapy.

Graphene oxide wrapped gold nanoparticles for intracellular Raman imaging and drug delivery

Graphene oxide wrapped gold nanoparticles (Au@NGO) were fabricated by a one-step synthesis. The surface enhanced Raman scattering (SERS) signal from Au@NGO was employed for intracellular Raman imaging in HeLa cancer cells. Anticancer drug doxorubicin was attached onto the nanoparticle surface through noncovalent interactions, and was delivered into HeLa cells for chemotherapy.

Targeted delivery of 5-aminolevulinic acid by multifunctional hollow mesoporous silica nanoparticles for photodynamic skin cancer therapy.

5-Aminolevulinic acid (5-ALA) is a precursor of a strong photosensitizer, protoporphyrin IX (PphIX), for photodynamic therapy (PDT). Developing appropriate delivery carriers that can assist 5-ALA in bypassing the lipophilic barrier to directly enter into cancer cells is a research focus. The improved delivery of 5-ALA is even important for skin cancer therapy through PDT process. In this work, targeting ligand folic acid (FA)-functionalized hollow mesoporous silica nanoparticles (HMSNPs) were fabricated to deliver 5-ALA for PDT against B16F10 skin cancer cells. The FA targeting ligand enabled selective endocytosis of 5-ALA loaded HMSNPs into cancer cells. PphIX formed from delivered 5-ALA exhibited high photocytotoxicity to the cancer cells in vitro.

Polymeric Prodrug Grafted Hollow Mesoporous Silica Nanoparticles Encapsulating Near-Infrared Absorbing Dye for Potent Combined Photothermal-Chemotherapy.

In this study, polymeric prodrug coated hollow mesoporous silica nanoparticles (HMSNs) with encapsulated near-infrared (NIR) absorbing dye were prepared and explored for combined photothermal-chemotherapy. A copolymer integrated with tert-butoxycarbonyl protected hydrazide groups and oligoethylene glycols was initially grafted on the surface of HMSNs via reversible addition-fragmentation chain-transfer (RAFT) polymerization followed by the deprotection to reactivate the hydrazide groups for the conjugation of anticancer drug doxorubicin (DOX). DOX was covalently bound onto the polymer substrate by acid-labile hydrazone bond and released quickly in weak acidic environment for chemotherapy. The hollow cavity of HMSNs was loaded with an NIR absorbing dye IR825 to form the final multifunctional hybrid denoted as HMSNs-DOX/IR825. The hybrid exhibited good dispersity and stability as well as high light-to-heat conversion efficiency. As revealed by confocal microscopy and flow cytometry analysis, the hybrid was efficiently taken up by cancer cells, and the conjugated DOX could be released under the cellular environment. In vitro cytotoxicity study demonstrated that anticancer activity of HMSNs-DOX/IR825 could be significantly improved by the NIR irradiation, which led to a satisfactory therapeutic efficacy through the combination treatment. Thus, the developed hybrid could be a promising candidate for the combined photothermal-chemotherapy of cancer.

Intracellular Delivery of Antisense Peptide Nucleic Acid by Fluorescent Mesoporous Silica Nanoparticles

In order to overcome poor cell permeability of antisense peptide nucleic acid (PNA), a fluorescent mesoporous silica nanoparticle (MSNP) carrier was developed to successfully deliver antisense PNA into cancer cells for effective silence of B-cell lymphoma 2 (Bcl-2) protein expression in vitro. First, fluorescent MSNP functionalized with disulfide bond bridged groups was fabricated and characterized. Antisense and negative control PNAs were synthesized and further conjugated with fluorescent dye cyanine 5. Then, the PNAs were covalently connected with fluorescent MSNP via amidation between amino group of PNAs and carboxylic acid group on the MSNP surface. High intracellular concentration of glutathione serves as a natural reducing agent, which could cleave the disulfide bond to trigger the PNA release in vitro. Confocal laser scanning microscopy studies prove that PNA conjugated MSNP was endocytosed by HeLa cancer cells, and redox-controlled intracellular release of antisense PNA from fluorescent MSNP was successfully achieved. Finally, effective silencing of the Bcl-2 protein expression induced by the delivered antisense PNA into HeLa cells was confirmed by Western blot assay.

Photocontrolled Nuclear-Targeted Drug Delivery by Single Component Photoresponsive Fluorescent Organic Nanoparticles of Acridin-9-Methanol

We report for the first time an organic nanoparticle based nuclear-targeted photoresponsive drug delivery system (DDS) for regulated anticancer drug release. Acridin-9-methanol fluorescent organic nanoparticles used in this DDS performed three important roles: (i) ″nuclear-targeted nanocarrier″ for drug delivery, (ii) ″phototrigger″ for regulated drug release, and (iii) fluorescent chromophore for cell imaging. In vitro biological studies reveal acridin-9-methanol nanoparticles of ~60 nm size to be very efficient in delivering the anticancer drug chlorambucil into the target nucleus, killing the cancer cells upon irradiation. Such targeted organic nanoparticles with good biocompatibility, cellular uptake property, and efficient photoregulated drug release ability will be of great benefit in the field of targeted intracellular controlled drug release.

Redox and pH Dual Responsive Polymer Based Nanoparticles for In Vivo Drug Delivery

Responsive nanomaterials have emerged as promising candidates as drug delivery vehicles in order to address biomedical diseases such as cancer. In this work, polymer-based responsive nanoparticles prepared by a supramolecular approach are loaded with doxorubicin (DOX) for the cancer therapy. The nanoparticles contain disulfide bonds within the polymer network, allowing the release of the DOX payload in a reducing environment within the endoplasm of cancer cells. In addition, the loaded drug can also be released under acidic environment. In vitro anticancer studies using redox and pH dual responsive nanoparticles show excellent performance in inducing cell death and apoptosis. Zebrafish larvae treated with DOX-loaded nanoparticles exhibit an improved viability as compared with the cases treated with free DOX by the end of a 3 d treatment. Confocal imaging is utilized to provide the daily assessment of tumor size on zebrafish larva models treated with DOX-loaded nanoparticles, presenting sustainable reduction of tumor. This work demonstrates the development of functional nanoparticles with dual responsive properties for both in vitro and in vivo drug delivery in the cancer therapy.

A dual responsive “turn-on” fluorophore for orthogonal selective sensing of biological thiols and hydrogen peroxide

Both thiols and hydrogen peroxide (H2O2) have great correlations with cancer and other diseases, and hence detection probes for sensing these agents may serve as early diagnostic tools. In this article, we report the development of a dual responsive probe that has the ability to generate two different responses upon reacting with thiols and H2O2 in a highly selective manner. The probe (FLB2SSCou) consists of a coumarin unit and a diboron xanthene spiro isobenzofuran group bridged by a disulfide bond. The detection experiments show that the probe could selectively respond to thiols and H2O2 when screening a substrate library containing 20 amino acids, homocysteine, glutathione, dithiothreitol and H2O2. The initial off state of the probe was a result of photo-induced electron transfer (PET) from the coumarin group to the non-fluorescing diboron xanthene spiro isobenzofuran group bridged by a disulfide bond. Reductive cleavage of the disulfide bond leads to the termination of this PET process, thus switching on the fluorescence of the probe. On the other hand, the oxidation of the diboron group by H2O2 converts the non-fluorescing group into a highly fluorescing fluorescein group. Time-dependent density functional theory calculations were then performed to explain the PET process, and the obtained results indicate that the PET process occurs from the second excited state (S2) into the first excited state (S1). Finally, imaging and detection experiments of the probe on HeLa cancer cells were conducted by means of the fluorescence microscopy and flow cytometry technique. It was observed that the fluorescence of the FLB2SSCou probe could be switched on by endogenous thiols and exogenous H2O2, demonstrating the applicability of this probe in both extracellular and intracellular environments. The present work exhibits the novel development of a dual responsive probe in contrast to commonly reported single responsive fluorescent probes, which may inspire the future design of multiple responsive fluorescent probes.

Imaging-Guided Drug Release from Glutathione-Responsive Supramolecular Porphysome Nanovesicles

Drug delivery systems that can be employed to load anticancer drugs and release them triggered by a specific stimulus, such as glutathione, are of great importance in cancer therapy. In this study, supramolecular porphysome nanovesicles that were self-assembled by amphiphilic porphyrin derivatives were successfully constructed, mainly driven by the π-π stacking, hydrogen bonding, and hydrophobic interactions, and were used as carriers of anticancer drugs. The nanovesicles are monodispersed in shape and uniform in size. The drug loading and in vitro drug release investigations indicate that these nanovesicles are able to encapsulate doxorubicin (DOX) to achieve DOX-loaded nanovesicles, and the nanovesicles could particularly release the loaded drug triggered by a high concentration of glutathione (GSH). More importantly, the drug release in cancer cells could be monitored by fluorescent recovery of the porphyrin derivative. Cytotoxicity experiments show that the DOX-loaded nanovesicles possess comparable therapeutic effect to cancer cells as free DOX. This study presents a new strategy in the fabrication of versatile anticancer drug nanocarriers with stimuli-responsive properties. Thus, the porphysome nanovesicles demonstrated here might offer an opportunity to bridge the gap between intelligent drug delivery systems and imaging-guided drug release.