Layered double hydroxides - poloxamer 188 nanocomposites based on exfoliation reassembling for improved cellular uptake and controlled delivery of methotrexate.

Exploitation of advanced methotrexate (MTX) delivery with nanocomposites has important clinical application value. Poloxamer 188 micelle and layered double hydroxide loaded with MTX (LDH-MTX) by exfoliation reassembling were used to prepare LDH-MTX-poloxamer 188 nanocomposites with good dispersibility and efficient cellular uptake for controlled drug delivery. The LDH-MTX-poloxamer 188 nanocomposites with sphere-like morphology, of which the average hydrodynamic diameter was <100 nm, were shown to have better dispersion state than naked LDH-MTX. Importantly, the LDH-MTX-poloxamer 188 nanocomposites could achieve significant sustained drug release and have obvious pH dependent responsive release ability. In addition, these nanocomposites also exhibited long-term and excellent in vitro antitumor efficacy as opposed to pure MTX or LDH-MTX as evident from cell viability. More interestingly, compared to pure FITC used to simulate MTX, LDH nanocomposites labeled with FITC were considered to have better cell adhesion through cell uptake. Therefore, the studied nanocomposites of LDH-MTX-poloxamer 188 can be further used as a new advanced MTX delivery nanovehicles with desired properties in future therapeutic aspects.

Self-assembled nanoparticles of reduction-sensitive poly (lactic-co-glycolic acid)-conjugated chondroitin sulfate A for doxorubicin delivery: preparation, characterization and evaluation.

In this study, reduction-sensitive self-assembled polymer nanoparticles based on poly (lactic-co-glycolic acid) (PLGA) and chondroitin sulfate A (CSA) were developed and characterized. PLGA was conjugated with CSA via a disulfide linkage (PLGA-ss-CSA). The critical micelle concentration (CMC) of PLGA-ss-CSA conjugate is 3.5 µg/mL. The anticancer drug doxorubicin (DOX) was chosen as a model drug, and was effectively encapsulated into the nanoparticles (PLGA-ss-CSA/DOX) with high loading efficiency of 15.1%. The cumulative release of DOX from reduction-sensitive nanoparticles was only 34.8% over 96 h in phosphate buffered saline (PBS, pH 7.4). However, in the presence of 20 mM glutathione-containing PBS environment, DOX release was notably accelerated and almost complete from the reduction-sensitive nanoparticles up to 96 h. Moreover, efficient intracellular DOX release of PLGA-ss-CSA/DOX nanoparticles was confirmed by CLSM assay in A549 cells. In vitro cytotoxicity study showed that the half inhibitory concentrations of PLGA-ss-CSA/DOX nanoparticles and free DOX against A549 cells were 1.141 and 1.825 µg/mL, respectively. Therefore, PLGA-ss-CSA/DOX nanoparticles enhanced the cytotoxicity of DOX in vitro. These results suggested that PLGA-ss-CSA nanoparticles could be a promising carrier for drug delivery.

[Progress in the study of core-crosslinked polymeric micelles in drug delivery system].

The core-crosslinked polymeric micelles were used as a new drug delivery system, which can decrease the premature drug release in blood circulation, improve the stability of the micelles, and effectively transport the drug into the therapy sites. Then the drug bioavailability increased further, while the side effect reduced. Most drugs were physically entrapped or chemically covalent with the polymer in the internals of micelles. Based on the various constitutions and properties of polymeric micelles as well as the special characteristics of body microenvironment, the environment-responsive or active targeting core-crosslinked micelles were designed and prepared. As a result, the drug controlled release behavior was obtained. In the present paper, the research progress of all kinds of core-crosslinked micelles which were published in recent years is introduced. Moreover, the characteristic and application prospect of these micelles in drug delivery system are analyzed and summarized.

Peptide-modified bioresponsive chondroitin sulfate micelles for targeted doxorubicin delivery in triple-negative breast cancer.

Triple-negative breast cancer is an offensive tumor that is highly challenging to cure. In this study, we developed novel polymeric nanoparticles that target dual receptors and respond to reducing conditions for chemotherapeutic drug release in the treatment of triple-negative breast cancer. Then we synthesized and characterized a targeted peptide-grafted chondroitin sulfate A-ss-deoxycholic acid (TCSSD) copolymer and prepare doxorubicin (DOX)-loaded TCSSD (TCSSD-D) micelles high-loading content. The bioresponsive drug release of TCSSD-D nanoparticles was demonstrated in a glutathione-containing phosphate buffer solution. We found that TCSSD-D effectively targeted CD44 and P-selectin receptors both in vitro and in vivo. TCSSD-D micelles were higher cytotoxicity and cellular uptake than unmodified DOX-containing micelles in MDA-MB-231 cells. Furthermore, TCSSD-D micelles showed the strongest suppression of tumor growth among three DOX-based formulations in triple-negative MDA-MB-231-bearing nude mice. These results suggest that amphiphilic TCSSD nanoparticles can serve as a targeted and intelligent delivery vehicle for triple-negative breast cancer therapy.

Preparation and evaluation of reduction-responsive micelles based on disulfide-linked chondroitin sulfate A-tocopherol succinate for controlled antitumour drug release.

OBJECTIVES: The study was to construct reduction-responsive chondroitin sulfate A (CSA)-conjugated TOS (CST) micelles with disulfide bond linkage, which was used for controlled doxorubicin (DOX) release and improved drug efficacy in vivo. METHODS: CST and non-responsive CSA-conjugated TOS (CAT) were synthesized, and the chemical structure was confirmed by Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, fluorescence spectrophotometer and dynamic light scattering. Antitumour drug DOX was physically encapsulated into CST and CSA by dialysis method. Cell uptake of DOX-based formulations was investigated by confocal laser scanning microscopy. In vitro cytotoxicity was studied in A549 and AGS cells. Furthermore, antitumour activity was evaluated in A549-bearing mice. KEY FINDINGS: CST and CAT can form self-assembled micelles, and have low value of critical micelle concentration. Notably, DOX-containing CST (D-CST) micelles demonstrated reduction-triggered drug release in glutathione-containing media. Further, reduction-responsive uptake of D-CST was observed in A549 cells. In addition, D-CST induced stronger cytotoxicity (P < 0.05) than DOX-loaded CAT (D-CAT) against A549 and AGS cells. Moreover, D-CST exhibited significantly stronger antitumour activity in A549-bearing nude mice than doxorubicin hydrochloride and D-CAT. CONCLUSIONS: The reduction-responsive CST micelles enhanced the DOX effect at tumour site and controlled drug release.

Polymeric nanoparticles of cholesterol-modified glycol chitosan for doxorubicin delivery: preparation and in-vitro and in-vivo characterization.

OBJECTIVES: Polymeric nanoparticles have been extensively studied as drug carriers. Chitosan and its derivatives have attracted significant attention in this regard but have limited application because of insolubility in biological solution. In this work, we attempted to utilize cholesterol-modified glycol chitosan (CHGC) self-aggregated nanoparticles to increase aqueous solubility, and to reduce side effects and enhance the antitumour efficacy of the anticancer drug doxorubicin. Methods CHGC nanoparticles were loaded with doxorubicin by a dialysis method, and their characteristics were determined by transmission electron microscopy examination, light-scattering study, in-vitro drug-release study, pharmacokinetic study in rats and in-vivo antitumour activity in mice. KEY FINDINGS: The resulting doxorubicin-loaded CHGC nanoparticles (DCNs) formed self-assembled aggregates in aqueous medium. From the observation by transmission electron microscopy, DCNs were almost spherical in shape. The mean diameters of these nanoparticles determined by dynamic light scattering were in the range of 237-336 nm as the doxorubicin-loading content increased from 1.73% to 9.36%. In-vitro data indicated that doxorubicin release from DCNs was much faster in phosphate-buffered saline at pH 5.5 than at pH 6.5 and 7.4, and the release rate was dependent on the loading content of doxorubicin in these nanoparticles. It was observed that DCN-16 (drug loaded content: 9.36%) exhibited prolonged circulation time in rat plasma and showed higher antitumour efficacy against S180-bearing mice than free doxorubicin. CONCLUSIONS: These results indicated that CHGC nanoparticles had potential as a carrier for insoluble anticancer drugs in cancer therapy.

Fabrication and characterization of nuclear localization signal-conjugated glycol chitosan micelles for improving the nuclear delivery of doxorubicin.

BACKGROUND: Supramolecular micelles as drug-delivery vehicles are generally unable to enter the nucleus of nondividing cells. In the work reported here, nuclear localization signal (NLS)-modified polymeric micelles were studied with the aim of improving nuclear drug delivery. METHODS: In this research, cholesterol-modified glycol chitosan (CHGC) was synthesized. NLS-conjugated CHGC (NCHGC) was synthesized and characterized using proton nuclear magnetic resonance spectroscopy, dynamic light scattering, and fluorescence spectroscopy. Doxorubicin (DOX), an anticancer drug with an intracellular site of action in the nucleus, was chosen as a model drug. DOX-loaded micelles were prepared by an emulsion/solvent evaporation method. The cellular uptake of different DOX formulations was analyzed by flow cytometry and confocal laser scanning microscopy. The cytotoxicity of blank micelles, free DOX, and DOX-loaded micelles in vitro was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in HeLa and HepG2 cells. RESULTS: The degree of substitution was 5.9 cholesterol and 3.8 NLS groups per 100 sugar residues of the NCHGC conjugate. The critical aggregation concentration of the NCHGC micelles in aqueous solution was 0.0209 mg/mL. The DOX-loaded NCHGC (DNCHGC) micelles were observed as being almost spherical in shape under transmission electron microscopy, and the size was determined as 248 nm by dynamic light scattering. The DOX-loading content of the DNCHGC micelles was 10.1%. The DOX-loaded micelles showed slow drug-release behavior within 72 hours in vitro. The DNCHGC micelles exhibited greater cellular uptake and higher amounts of DOX in the nuclei of HeLa cells than free DOX and DOX-loaded CHGC (DCHGC) micelles. The half maximal inhibitory concentration (IC(50)) values of free DOX, DCHGC, and DNCHGC micelles against HepG2 cells were 4.063, 0.591, and 0.171 µg/mL, respectively. Moreover, the IC(50) values of free DOX (3.210 µg/mL) and the DCHGC micelles (1.413 µg/mL) against HeLa cells were nearly 6.96- and 3.07-fold (P < 0.01), respectively, higher than the IC(50) value of the DNCHGC micelles (0.461 µg/mL). CONCLUSION: The results of this study suggest that novel NCHGC micelles could be a potential carrier for nucleus-targeting delivery.

Structure-transfection activity relationships with glucocorticoid-polyethyl-enimine conjugate nuclear gene delivery systems.

Efficient nuclear gene delivery is essential for successful gene therapy. It was previously reported that the transport of DNA into nucleus may be facilitated by glucocorticoid (GC). In this study, five glucocorticoids with different structures and potencies were conjugated with low molecular weight PEI 1800, and the degree of substitution of glucocorticoids was controlled to be close to each other. The glucocorticoid-polyethylenimine (GC-PEI)/pDNA complexes were prepared and their physico-chemical properties and transfection efficiency were investigated. The results showed that the complexes had similar physico-chemical properties, but their transfection activities were different statistically. In order to explore the reason of this difference, the affinity of GC-PEI polymer with GC receptor was analyzed by the application of molecular docking, and the correlation between transfection activity and the potency of five GC was investigated. The result showed that receptor binding of five GC was different and transgene expression enhanced linearly with the increasing GC potency, but logP. In addition, confocal microscopy examination confirmed that GC-PEI/DNA complexes were more effectively translocated in the nucleus than PEI 25K or PEI 1800 complexes and the cytotoxicities of the GC-PEI polymers were lower than that of PEI 25K. These results demonstrated that transfection activity of GC-PEI polymer correlated with its GC potency, and this regularity might be useful for the development of more efficient GC substituted polymer as promising nuclear-targeting carrier.