Gene/Protein Disease Symptom Drug Enzyme Compound
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Modeling the influence of a technology such as nanoparticle systems on drug delivery is beneficial in rational formulation design. While there are many studies showing drug delivery enhancement by nanoparticles, the literature provides little guidance regarding when nanoparticles are useful for delivery of a given drug. A model was developed predicting intracellular drug concentration in cultured cells dosed with nanoparticles. The model considered drug release from nanoparticles as well as drug and nanoparticle uptake by the cells as the key system processes. Mathematical expressions for these key processes were determined using experiments in which each process occurred in isolation. In these experiments, intracellular delivery of saquinavir, a low solubility drug dosed as a formulation of poly(ethylene oxide)-modified poly(epsilon- caprolactone) (PEO-PCL) nanoparticles, was studied in THP-1 human monocyte/macrophage (Mo/Mac) cells. The model accurately predicted the enhancement in intracellular concentration when drug was administered in nanoparticles compared to aqueous solution. This simple model highlights the importance of relative kinetics of nanoparticle uptake and drug release in determining overall enhancement of intracellular drug concentration when dosing with nanoparticles.
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PMID:A model predicting delivery of saquinavir in nanoparticles to human monocyte/macrophage (Mo/Mac) cells. 1855 95

The aim of the present study was to develop a polymeric delivery system for water-insoluble drug oridonin. Amphiphilic block copolymers, poly(epsilon-caprolactone)-poly(ethylene glycol)-poly (epsilon-caprolactone) (PCL-PEO-PCL), were synthesized by ring-opening polymerization of caprolactone initiated by the hydroxyl groups of poly(ethylene glycol)6000 (PEG-6000) with stannous octoate as catalyzer. Oridonin-loaded PCL-PEO-PCL copolymer nanoparticles (ORI-PCL-PEO-PCL-NPs) were prepared by the interfacial deposition method. The mean particle size of the drug-loaded nanoparticles was 97.5 nm and the zeta potential was - 25 mV. The entrapment efficiency and actual drug loading of the nanoparticles were 87.52% +/- 1.86% and 8.63% +/- 0.49%, respectively. The antitumor activity of ORI-PCL-PEO-PCL-NPs was evaluated by measuring changes in tumor volumes, tumor weights, and survival rates of mice with grafted hepatoma (H22). The results indicated that ORI-PCL-PEO-PCL-NPs prolonged the survival time of mice and exhibited higher therapeutic efficacy compared with free oridonin. Thus, ORI-PCL-PEO-PCL-NPs may be used as a promising delivery system for liver cancer treatment.
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PMID:Oridonin-loaded poly(epsilon-caprolactone)-poly(ethylene oxide)-poly(epsilon-caprolactone) copolymer nanoparticles: preparation, characterization, and antitumor activity on mice with transplanted hepatoma. 1860 60

In this study, the effect of MDR-1 gene silencing, using small interfering RNA (siRNA), and paclitaxel (PTX) co-therapy in overcoming tumor multidrug resistance was examined. Poly(ethylene oxide)-modified poly(beta-amino ester) (PEO-PbAE) and PEO-modified poly(epsilon-caprolactone) (PEO-PCL) nanoparticles were formulated to efficiently encapsulate MDR-1 silencing siRNA and PTX, respectively. Upon administration in multidrug resistant SKOV3(TR) human ovarian adenocarcinoma cells, siRNA-mediated MDR-1 gene silencing was evident at 100 nM dose. Combination of MDR-1 gene silencing and nanoparticle-mediated delivery significantly influenced the cytotoxic activity of PTX in SKOV3(TR) cells similar to what was observed in drug sensitive SKOV3 cells. We speculate that the enhancement in cytotoxicity was due to an increase in intracellular drug accumulation upon MDR-1 gene silencing leading to an apoptotic cell-kill effect. Taken together, these preliminary results are highly encouraging for the development of combination nano-therapeutic strategies that combine gene silencing and drug delivery to provide more potent therapeutic effect, especially in refractory tumors.
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PMID:Evaluations of combination MDR-1 gene silencing and paclitaxel administration in biodegradable polymeric nanoparticle formulations to overcome multidrug resistance in cancer cells. 1861 15

The RNA interference (RNAi) technology has been successfully used in elucidating mechanisms behind various biological events. However, in the absence of safe and effective carriers for in vivo delivery of small interfering RNAs (siRNAs), application of this technology for therapeutic purposes has lagged behind. The objective of this research was to develop promising carriers for siRNA delivery based on degradable poly(ethylene oxide)-block-polyesters containing polycationic side chains on their polyester block. Toward this goal, a novel family of biodegradable poly(ethylene oxide)-block-poly(epsilon-caprolactone) (PEO-b-PCL) based copolymers with polyamine side chains on the PCL block, i.e., PEO-b-PCL with grafted spermine (PEO-b-P(CL-g-SP)), tetraethylenepentamine (PEO-b-P(CL-g-TP)), or N,N-dimethyldipropylenetriamine (PEO-b-P(CL-g-DP)) were synthesized and evaluated for siRNA delivery. The polyamine-grafted PEO-b-PCL polymers, especially PEO-b-P(CL-g-SP), demonstrated comparable toxicity to PEO-b-PCL in vitro. The polymers were able to effectively bind siRNA, self-assemble into micelles, protect siRNA from degradation by nuclease and release complexed siRNA efficiently in the presence of low concentrations of polyanionic heparin. Based on flow cytometry and confocal microscopy, siRNA formulated in PEO-b-P(CL-g-SP) and PEO-b-P(CL-g-TP) micelles showed efficient cellular uptake through endocytosis by MDA435/LCC6 cells transfected with MDR-1, which encodes for the expression of P-glycoprotein (P-gp). The siRNA formulated in PEO-b-P(CL-g-SP) and PEO-b-P(CL-g-TP) micelles demonstrated effective endosomal escape after cellular uptake. Finally, MDR-1-targeted siRNA formulated in PEO-b-P(CL-g-SP) and PEO-b-P(CL-g-TP) micelles exhibited efficient gene silencing for P-gp expression. The results of this study demonstrated the promise of novel amphiphilic PEO-b-P(CL-g-polyamine) block copolymers for efficient siRNA delivery.
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PMID:Biodegradable amphiphilic poly(ethylene oxide)-block-polyesters with grafted polyamines as supramolecular nanocarriers for efficient siRNA delivery. 1883 58

This work focused on the preparation and the aqueous solution properties of hybrid polymeric micelles consisting of a hydrophobic poly(epsilon-caprolactone) (PCL) core and a mixed shell of hydrophilic poly(ethylene oxide) (PEO) and pH-sensitive poly(2-vinylpyridine) (P2VP). The hybrid micelles were successfully prepared by the rapid addition of acidic water to a binary solution of PCL(34)-b-PEO(114) and PCL(32)-b-P2VP(52) diblock copolymers in N,N-dimethylformamide. These micelles were pH-responsive as result of the pH-dependent ionization of the P2VP block. The impact of pH on the self-assembly of the binary mixture of diblocks-thus on the composition, shape, size and surface properties of the micelles-was studied by a variety of experimental techniques, i.e., dynamic and static light scattering, transmission electron microscopy, Zeta potential, fluorescence spectroscopy and complement hemolytic 50 test.
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PMID:Synthesis and pH-dependent micellization of diblock copolymer mixtures. 1893 Feb 46

In the present work, molecular dynamics (MD) simulation was applied to study the solubility of two water-insoluble drugs, fenofibrate and nimodipine, in a series of micelle-forming PEO-b-PCL block copolymers with combinations of blocks having different molecular weights. The solubility predictions based on the MD results were then compared with those obtained from solubility experiments and by the commonly used group contribution method (GCM). The results showed that Flory-Huggins interaction parameters computed by the MD simulations are consistent with the solubility data of the drug/PEO-b-PCL systems, whereas those calculated by the GCM significantly deviate from the experimental observation. We have also accounted for the possibility of drug solubilization in the PEO block of PEO-b-PCL.
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PMID:Application of molecular dynamics simulation to predict the compatability between water-insoluble drugs and self-associating poly(ethylene oxide)-b-poly(epsilon-caprolactone) block copolymers. 1893 98

The reversible transitions of the lamellae of a crystalline-crystalline diblock copolymer from the melt to crystallites were studied using simultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) measurements with synchrotron radiation. A symmetric poly(ethylene oxide)-poly( varepsilon -caprolactone) diblock copolymer was chosen for this study. We showed in the course of the block copolymer crystallisation that the time-resolved integrated intensity I (int) was proportional to the product of the volume fractions of the PEO and PCL phases and the scattering contrast due to the electron density difference. These results demonstrated that simultaneous SAXS/WAXS measurements could be used to monitor the crystallisation process in two domains of different sizes at the same time.
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PMID:Study of temperature dependence of crystallisation transitions of a symmetric PEO-PCL diblock copolymer using simultaneous SAXS and WAXS measurements with synchrotron radiation. 1903 Oct 90

Gastric acidity is the main factor affecting viability of probiotics in the gastrointestinal tract (GIT). This study investigated the survival in simulated gastrointestinal fluids of Bifidobacterium longum Bb-46 encapsulated in interpolymer complexes formed in supercritical carbon dioxide (scCO(2)). Bacteria were exposed sequentially to simulated gastric fluid (SGF, pH 2) for 2 h and simulated intestinal fluid (SIF, pH 6.8) for 6 or 24 h. Total encapsulated bacteria were determined by suspending 1 g of product in SIF for 6 h at 37 degrees C prior to plating out. Plates were incubated anaerobically at 37 degrees C for 72 h. The interpolymer complex displayed pH-responsive release properties, with little to no release in SGF and substantial release in SIF. There was a limited reduction in viable counts at the end of exposure period due to encapsulation. Protection efficiency of the interpolymer complex was improved by addition of glyceryl monostearate (GMS). Gelatine capsules delayed release of bacteria from the interpolymer complex thus minimizing time of exposure to the detrimental conditions. Use of poly(caprolactone) (PCL), ethylene oxide-propylene oxide triblock copolymer (PEO-PPO-PEO) decreased the protection efficiency of the matrix. Interpolymer complex encapsulation showed potential for protection of probiotics and therefore for application in food and pharmaceuticals.
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PMID:Supercritical carbon dioxide interpolymer complexes improve survival of B. longum Bb-46 in simulated gastrointestinal fluids. 1906 22

Interdisciplinary investigation at the interface of chemistry, engineering, and medicine has enabled the development of self-assembled nanomaterials with novel biochemical and electro-optical properties. We have recently shown that emissive polymersomes, polymer vesicles incorporating porphyrin-based fluorophores, feature large integrated-emission oscillator strengths and narrow emission bands; these nanoscale assemblies can be further engineered to fluoresce at discrete wavelengths throughout the visible and near-infrared (NIR) spectral domains. As such, emissive polymersomes effectively define an organic-based family of soft-matter quantum-dot analogs that possess not only impressive optical properties, but also tunable physical and biomaterial characteristics relative to inorganic fluorescent nanoparticles.Here, we expand upon our initial studies on poly(ethyleneoxide)-block-poly(butadiene)-based vesicles to examine fluorophore membrane-loading in other polymersome systems. Through modulation of fluorophore ancilliary group substituents and choice of polymer chain chemistries, we are able to predictably control intramembranous polymer-fluorophore interactions; these phenomena, in turn, influence the nature of fluorophore solvation, local dielectric environment, and emission quantum yield within emissive polymersome assemblies. By utilizing different classes of vesicle-generating diblock copolymers, including bioresorbable poly(ethyleneoxide)-block-poly(epsilon-caprolactone) (PEO-b-PCL) and poly(ethyleneoxide)-block-poly(gamma-methyl-epsilon-caprolactone) (PEO-b-PMCL), we ascertain general principles important for engineering nanoscale optical vesicles. Further, this work heralds the first generation of fully-biodegradable fluorescent nanoparticles suitable for deep-tissue in vivo imaging.
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PMID:Controlling Bulk Optical Properties of Emissive Polymersomes Through Intramembranous Polymer-Fluorophore Interactions. 1907 89

Dexibuprofen, or S(+)-ibuprofen, is the pharmacologically effective enantiomer of racemic ibuprofen. Since dexibuprofen has a low melting point, the amorphous form having a high melting point was prepared with the fused solid dispersion method. With the fused solid dispersion of dexibuprofen, immediate release tablets, extended release tablets, and dual release tablets were compressed and their dissolution profiles compared. The dissolution profiles of the extended release and the dual release tablet depended on the amount of used release modulators (PEO 5,000,000). The release profiles of extended release tablets and extended release part of dual release tablets were well fitted to zero-order release model. The correlation coefficient ranged from 0.982 to 0.995. A pharmacokinetic evaluation where healthy volunteers took tablets of DRT-1 (300 mg) once and the reference drug, two tablets of conventional immediate release tablet (Daxfen, 300 mg), with a 6-h interval between them was studied. The 90% confidence interval for the ratio of the logarithmically transformed AUC (0-24 h), Cmax (0-6 h), and Cmax (6-24 h) values of the dual release tablet compared to those of the conventional immediate release tablet were calculated to be between 0.9176 and 1.0007, 0.9240 and 1.1968, and 0.8713 and 1.1414, respectively. When the immediate release tablet was taken two times with a six hour interval between doses it showed a bioequivalent effect to taking the dual release tablet once within 12 h. The Cmax was reached due to the rapid absorption of the immediate release portion of the dual release tablet and the AUC was maintained due to continuous absorption of the extended release portion.
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PMID:Formulation of a extended release tablet containing dexibuprofen. 1909 35


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