Dual gatekeepers-modified mesoporous organic silica nanoparticles for synergistic photothermal-chemotherapy of breast cancer.

HYPOTHESIS: Construction of dual gatekeepers-functionalized mesoporous organic silica nanoparticles (MONs) with both physical and chemical mechanisms for modulated drug delivery properties provides one solution to the extracellular stability vs. intracellular high therapeutic efficiency of MONs that hold great potential for clinical translations. EXPERIMENTS: We reported herein facile construction of diselenium-bridged MONs decorated with dual gatekeepers, i.e., azobenzene (Azo)/polydopamine (PDA) for both physical and chemical modulated drug delivery properties. Specifically, Azo can act as a physical barrier to block DOX in the mesoporous structure of MONs for extracellular safe encapsulation. The PDA outer corona serves not only as a chemical barrier with acidic pH-modulated permeability for double insurance of minimized DOX leakage in the extracellular blood circulation but also for inducing a PTT effect for synergistic PTT and chemotherapy of breast cancer. FINDINGS: An optimized formulation, DOX@(MONs-Azo3)@PDA resulted in approximately 1.5 and 2.4 fold lower IC50 values than DOX@(MONs-Azo3) and (MONs-Azo3)@PDA controls in MCF-7 cells, respectively, and further mediated complete tumor eradication in 4T1 tumor-bearing BALB/c mice with insignificant systematic toxicity due to the synergistic PTT and chemotherapy with enhanced therapeutic efficiency.

Facile fabrication of a novel hybrid nanoparticles by self-assembling based on pectin-doxorubicin conjugates for hepatocellular carcinoma therapy.

Hepatocellular carcinoma (HCC) is one of the greatest public health problems worldwide, and chemotherapy remains the major approach for the HCC treatment. Doxorubicin (DOX) is one of the anthracycline antibiotics but its clinical use is limited due to its severe cardiotoxicity. In this study, novel hybrid nanoparticles by self-assembling based on pectin-doxorubicin conjugates (PDC-NPs) were fabricated for HCC treatment. The stabilized structure of the PDC-NPs was characterized by methylene blue absorption, the size, zeta potential and the morphology, which was investigated by Zetasizer nanoparticle analyzer and transmission electron microscope (TEM), of nanoparticles. The PDC-NPs achieved a sustained and prolonged release ability, which was illustrated with in vitro drug release profiles, anti-cell proliferation study, cellular uptake assay and in vivo pharmacokinetics analysis. Biocompatibility of the PDC-NPs was assessed with bovine serum albumin (BSA) adsorption test, hemolysis activity examination and viability evaluation of human umbilical vein endothelial cells. Importantly, in vivo studies of the PDC-NPs, which were performed in the athymic BALB/c nude mice, demonstrated that the PDC-NPs significantly reduced the lethal side effect of DOX. Additionally, the H&E staining and serum biochemistry study further confirmed the excellent biological security of the PDC-NPs.

The In-Situ One-Step Synthesis of a PDC Macromolecular Pro-Drug and the Fabrication of a Novel Core-Shell Micell.

The development of slow release nano-sized carriers for efficient antineoplastic drug delivery with a biocompatible and biodegradable pectin-based macromolecular pro-drug for tumor therapy has been reported in this study. Pectin-doxorubicin conjugates (PDC), a macromolecular pro-drug, were prepared via an amide condensation reaction, and a novel amphiphilic core-shell micell based on a PDC macromolecular pro-drug (PDC-M) was self-assembled in situ, with pectin as the hydrophilic shell and doxorubicin (DOX) as the hydrophobic core. Then the chemical structure of the PDC macromolecular pro-drug was identified by both Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy ((1)H-NMR), and proved that doxorubicin combined well with the pectin and formed macromolecular pro-drug. The PDC-M were observed to have an unregularly spherical shape and were uniform in size by scanning electron microscopy (SEM). The average particle size of PDC-M, further measured by a Zetasizer nanoparticle analyzer (Nano ZS, Malvern Instruments), was about 140 nm. The encapsulation efficiency and drug loading were 57.82% ± 3.7% (n = 3) and 23.852% ±2.3% (n = 3), respectively. The in vitro drug release behaviors of the resulting PDC-M were studied in a simulated tumor environment (pH 5.0), blood (pH 7.4) and a lysosome media (pH 6.8), and showed a prolonged slow release profile. Assays for antiproliferative effects and flow cytometry of the resulting PDC-M in HepG2 cell lines demonstrated greater properties of delayed and slow release as compared to free DOX. A cell viability study against endothelial cells further revealed that the resulting PDC-M possesses excellent cell compatibilities and low cytotoxicities in comparison with that of the free DOX. Hemolysis activity was investigated in rabbits, and the results also demonstrated that the PDC-M has greater compatibility in comparison with free DOX. This shows that the resulting PDC-M can ameliorate the hydrophobicity of free DOX. This work proposes a novel strategy for in-situ one-step synthesis of macromolecular pro-drugs and fabrication of a core-shell micelle, demonstrating great potential for cancer chemotherapy.

In vitro and in vivo evaluation of pectin-based nanoparticles for hepatocellular carcinoma drug chemotherapy.

The fabrication and evaluation of a natural pectin-based drug delivery system are reported in this study. The drug delivery system displays specific active targeting ability to hepatocellular carcinoma due to the presence of excess galactose residues in the polymer structure as the natural targeting ligands. The system was prepared under very mild conditions in an aqueous medium containing Ca(2+) and CO3(2-) ions, generating uniform pectin-based nanoparticles with an average diameter of 300 nm, and the drug-loading content of anticancer drug 5-fluorouracil (5-FU) is around 24.8%. Cytotoxicity study of the 5-FU-loaded nanoparticles (5-FU-NPs) in HepG2 and A549 cell lines demonstrated their greater potency in killing cancer cells with overexpressed asialoglycoprotein receptor (ASGPR) on the cell surface, compared to that of the free drug. Pharmacokinetics study using Sprague-Dawley (SD) rats further confirmed that the drug-loaded nanoparticles showed a much longer half-life in the circulation fluids than the free drug. Tissue distribution was investigated on Kunming mice, and the results also demonstrated that the 5-FU-NPs has a long circulation effect. Taken together, the pectin-based drug delivery systems exhibit size-induced prolonged circulation as well as ASGP receptor-mediated targeting ability to cancer cell lines; therefore, it is a promising platform for the treatment of hepatocellular carcinoma.

Hybrid nanospheres and vesicles based on pectin as drug carriers.

A novel strategy was developed to prepare nanospheres and vesicles as drug carriers. The drug-loaded pectin nanospheres and vesicles were fabricated in aqueous media containing Ca2+ and CO3(2-) ions under very mild conditions, which did not involve any surfactant. Through adjusting the preparation conditions, nanosized drug delivery systems with diverse morphologies, that is, nanospheres and vesicles, could be obtained. This technique could offer good control over the morphology and the size of nanospheres and vesicles. The morphologies of the aggregates were observed by environmental scanning electron microscopy and transmission electron microscopy. 5-Fluorouracil (5-FU), an antineoplastic drug, was encapsulated in the nanospheres and vesicles, and the in vitro drug release at different pH values was investigated. With the presence of Ca2+ and CO3(2-) ions in the pectin-based nanospheres/vesicles, the release of the low molecular weight drug could be effectively sustained from the highly hydrolyzed polysaccharide-based drug delivery systems.

Composite microparticle drug delivery systems based on chitosan, alginate and pectin with improved pH-sensitive drug release property.

Composite microparticle drug delivery systems based on chitosan, alginate and pectin with improved pH sensitivity were developed for oral delivery of protein drugs, using bovine serum albumin (BSA) as a model drug. The composite drug-loaded microparticles with a mean particle size less than 200mum were prepared by a convenient shredding method. Since the microparticles were formed by tripolyphosphate cross-linking, electrostatic complexation by alginate and/or pectin, as well as ionotropic gelation with calcium ions, the microparticles exhibited an improved pH-sensitive drug release property. The in vitro drug release behaviors of the microparticles were studied in simulated gastric (pH 1.2 and pH 5.0), intestinal (pH 7.4) and colonic (pH 6.0 and pH 6.8 with enzyme) media. For the composite microparticles with suitable compositions, the releases of BSA at pH 1.2 and pH 5.0 could be effectively sustained, while the releases at pH 7.4, pH 6.8 and pH 6.0 increased significantly, especially in the presence of pectinase. These results clearly suggested that the microparticles had potential for site-specific protein drug delivery through oral administration.