Monthly Archives: September 2014

New publication utilizes Polyscitech PLGA-PEG-PLGA thermogel for delivery of triamcinolone as macular degeneration treatment

PolySciTech (www.polyscitech.com) provides a wide array of PLGA-PEG-PLGA thermogels (AK12, AK24, AK88) for depot drug delivery applications.  Recently researchers at University of South Florida and Virginia Tech-Wake Forest utilized PolySciTech PEG-PLGA polymers (AK24) to generate a nanoparticle and thermogel based drug delivery system for administration of triamcilone. This system can be injected as a liquid into the eye and solidify leading to a biocompatible, sustained release delivery system. Read more: Hirani, Anjali, Aditya Grover, Yong W. Lee, Yashwant Pathak, and Vijaykumar Sutariya. “Triamcinolone acetonide nanoparticles incorporated in thermoreversible gels for age-related macular degeneration.” Pharmaceutical Development and Technology 0 (2014): 1-7. http://informahealthcare.com/doi/abs/10.3109/10837450.2014.965326

 

“Abstract: Age-related macular degeneration (AMD) is one of the leading causes of blindness in the US affecting millions yearly. It is characterized by intraocular neovascularization, inflammation and retinal damage which can be ameliorated through intraocular injections of glucocorticoids. However, the complications that arise from repetitive injections as well as the difficulty posed by targeting the posterior segment of the eye make this interesting territory for the development of novel drug delivery systems (DDS). In the present study, we described the development of a DDS composed of triamcinolone acetonide-encapsulated PEGylated PLGA nanoparticles (NP) incorporated into PLGA–PEG–PLGA thermoreversible gel and its use against VEGF expression characteristic of AMD. We found that the NP with mean size of 208 ± 1.0 nm showed uniform size distribution and exhibited sustained release of the drug. We also demonstrated that the polymer can be injected as a solution and transition to a gel phase based on the biological temperature of the eye. Additionally, the proposed DDS was non-cytotoxic to ARPE-19 cells and significantly reduced VEGF expression by 43.5 ± 3.9% as compared to a 1.53 ± 11.1% reduction with triamcinolone. These results suggest the proposed DDS will contribute to the development of novel therapeutic strategies for AMD. Keywords: Age-related macular degeneration, PLGA nanoparticles, triamcinolone acetonide, thermoreversible gel, VEGF”

PEG-PLA used to improve storage stability of Laccase biocatalyst

PolySciTech (www.polyscitech.com) provides a wide array of PEG-PLA block copolymers.  Recently these copolymers have been utilized to generate an emulsion of Laccase allow for liquid storage of the delicate enzyme for up to 12 days. Read more Moniruzzaman, Muhammad, Yoichiro Nao, Sekhar Bhattacharjee, and Tsutomu Ono. “Laccase Incorporated into PEG-PLA Polymer as Active and Stable Biocatalyst for Ionic Liquids Media.” In Applied Mechanics and Materials, vol. 625, pp. 333-336. 2014. http://www.scientific.net/AMM.625.333

“Abstract: Laccase Y20 (EC.1.10.3.2) was coated with poly (ethylene glycol)-block-polylactide (PEG-PLA, MW = 27680) via water-in-oil emulsion, and the activity and stability of the resulting PEG-PLA-laccase complex have been compared to those for the native laccase and lyophilized native laccase in an ionic liquid (IL) [C2mim][PF6] (1-ethyl-3-methylimidazolium hexafluorophosphate. The formation of spherical PEG-PLA-laccase complex of 330-480 nm was demonstrated by scanning electron microscopy. This polymer-laccase complex retained most of its enzymatic catalytic activity and exhibited excellent storage stability in IL, with over 70% of its initial activity retained after 12 days of storage in IL at 40 °C, whereas it was about 20% for native laccase under the identical conditions. This strategy could be employed to fabricate polymer based composites materials with novel biological functions.”

New publication uses PolySciTech PLGA-cysteine (PolyVivo AI25) as part of cancer treatment by targeted delivery of apoptosis inducing cytochrome C

PolySciTech (www.polyscitech.com) provides a wide array of reactive intermediate polymers. One of our products AI25 (PLGA-Cysteine ethyl ester endcap) was recently utilized in a publication in which it was conjugated to cytochrome C in order control the time and nature of drug release. Read more: Read More: Morales-Cruz, Moraima, Cindy M. Figueroa, Tania González-Robles, Yamixa Delgado, Anna Molina, Jessica Méndez, Myraida Morales, and Kai Griebenow. “Activation of caspase-dependent apoptosis by intracellular delivery of cytochrome c-based nanoparticles.” Journal of nanobiotechnology 12, no. 1 (2014): 33. Full-Text: http://www.biomedcentral.com/content/pdf/s12951-014-0033-9.pdf

“Abstract: Background: Cytochrome c is an essential mediator of apoptosis when it is released from the mitochondria to the cytoplasm. This process normally takes place in response to DNA damage, but in many cancer cells (i.e., cancer stem cells)it is disabled due to various mechanisms. However, it has been demonstrated that the targeted delivery of Cytochrome c directly to the cytoplasm of cancer cells selective initiates apoptosis in many cancer cells. In this work we designed a novel nano-sized smart Cytochrome c drug delivery system to induce apoptosis in cancer cells upon delivery. Results: Cytochrome c was precipitated with a solvent-displacement method to obtain protein nanoparticles. The size of the Cytochrome c nanoparticles obtained was 100-300 nm in diameter depending on the conditions used, indicating good potential to passively target tumors by the Enhanced Permeability and Retention effect. The surface of Cytochrome c nanoparticles was decorated with poly (lactic-co-glycolic) acid-SH via the linker succinimidyl 3-(2-pyridyldithio)propionate to prevent premature dissolution during delivery. The linker connecting the polymer to the protein nanoparticle contained a disulfide bond thus allowing polymer shedding and subsequent Cytochrome c release under intracellular reducing conditions. A cell-free caspase-3 assay revealed more than 80% of relative caspase activation by Cytochrome c after nanoprecipitation and polymer modification when compared to native Cytochrome c. Incubation of HeLa cells with the Cytochrome c based-nanoparticles showed significant reduction in cell viability after 6 hours while native Cytochrome c showed none. Confocal microscopy confirmed the induction of apoptosis in HeLa cells when they were stained with 4’,6-diamidino-2-phenylindole and propidium iodide after incubation with the Cytochrome c-based nanoparticles. Conclusions: Our results demonstrate that the coating with a hydrophobic polymer stabilizes Cytochrome c nanoparticles allowing for their delivery to the cytoplasm of target cells. After smart release of Cytochrome c intothe cytoplasm, it induced programmed cell death. Keywords: Drug delivery, Protein nanoparticles, PLGA, Passive targeting, Triggered release”

PLA from Polyscitech used to measure esterase activity

PolySciTech (www.polyscitech.com) provides a wide array of polyester products such as PLA and PLGAs of varying sizes and monomer ratios. Recently researchers have utilized PLA from PolySciTech as a means to test the activity of a variety of esterases at different conditions by measuring the degradation impact these enzymes had on PLA. Read more: Tchigvintsev, Anatoli, Hai Tran, Ana Popovic, Filip Kovacic, Greg Brown, Robert Flick, Mahbod Hajighasemi et al. “The environment shapes microbial enzymes: five cold-active and salt-resistant carboxylesterases from marine metagenomes.” Applied Microbiology and Biotechnology (2014): 1-14. http://link.springer.com/article/10.1007/s00253-014-6038-3

“Abstract: Most of the Earth’s biosphere is cold and is populated by cold-adapted microorganisms. To explore the natural enzyme diversity of these environments and identify new carboxylesterases, we have screened three marine metagenome gene libraries for esterase activity. The screens identified 23 unique active clones, from which five highly active esterases were selected for biochemical characterization. The purified metagenomic esterases exhibited high activity against α-naphthyl and p-nitrophenyl esters with different chain lengths. All five esterases retained high activity at 5 °C indicating that they are cold-adapted enzymes. The activity of MGS0010 increased more than two times in the presence of up to 3.5 M NaCl or KCl, whereas the other four metagenomic esterases were inhibited to various degrees by these salts. The purified enzymes showed different sensitivities to inhibition by solvents and detergents, and the activities of MGS0010, MGS0105 and MGS0109 were stimulated three to five times by the addition of glycerol. Screening of purified esterases against 89 monoester substrates revealed broad substrate profiles with a preference for different esters. The metagenomic esterases also hydrolyzed several polyester substrates including polylactic acid suggesting that they can be used for polyester depolymerization. Thus, esterases from marine metagenomes are cold-adapted enzymes exhibiting broad biochemical diversity reflecting the environmental conditions where they evolved.”

Aptamer-conjugated PLA-PEG nanoparticles for delivery of doxorubicin to liver cancer

PolyScitech (www.polyscitech.com) provides a wide array of functionalized PLA/PLGA-PEG block copolymers with –COOH, Maleimide, -NHS, bromoacetamide, and other PEG terminus functionality for conjugation to targeting ligands and aptamers. Recently these types of polymers were conjugated to tumor-specific aptamer TLS11a and utilized in nanoparticle form to deliver doxorubicin to liver cancer cells.  Read more: Shannon E. Weigum ; Melissa Sutton ; Eugenia Barnes ; Sarah Miller and Tania Betancourt “Targeting hepatocellular carcinoma with aptamer-functionalized PLGA/PLA-PEG nanoparticles”, Proc. SPIE 9166, Biosensing and Nanomedicine VII, 916605 (August 27, 2014); doi:10.1117/12.2062283; http://dx.doi.org/10.1117/12.2062283

“abstract: Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide, particularly in regions where chronic Hepatitis B and C infections are common. Nanoparticle assemblies that incorporate high-affinity aptamers which specifically bind malignant hepatocellular carcinoma cells could be useful for targeted drug delivery or enhancing contrast with existing ablation therapies. The in vitro interactions of a tumor-specific aptamer, TLS11a, were characterized in a hepatoma cell line via live-cell fluorescence imaging, SDS-PAGE and Western Blotting techniques. Cell surface binding of the aptamer-AlexaFluor®546 conjugate was found to occur within 20 minutes of initial exposure, followed by internalization and localization to late endosomes or lysosomes using a pH-sensitive LysoSensor™ Green dye and confocal microscopy. Aptamer-functionalized polymer nanoparticles containing poly(lactic-co-glycolic acid) (PLGA) and poly(lactide)-b-poly(ethylene glycol) (PLA-PEG) were then prepared by nanoprecipitation and passively loaded with the chemotherapeutic agent, doxorubicin, yielding spherical nanoparticles approximately 50 nm in diameter. Targeted drug delivery and cytotoxicity was assessed using live/dead fluorescent dyes and a MTT colorimetric viability assay with elevated levels of cell death found in cultures treated with either the aptamer-coated and uncoated polymer nanoparticles. Identification and characterization of the cell surface protein epitope(s) recognized by the TLS11a aptamer are ongoing along with nanoparticle optimization, but these preliminary studies support continued investigation of this aptamer and functionalized nanoparticle conjugates for targeted labeling and drug delivery within malignant hepatocellular carcinomas. Topics: Liver cancer ; Nanoparticles ; Polymers ; Cell death ; Proteins ; Luminescence ; Cancer ; Colorimetry ; Confocal microscopy”

New Publication utilizes Mal-PEG-PLGA (Polyvivo AI20) and polyaspartic acid to form bone-tissue targeted nanoparticle.

PolySciTech (www.polyscitech.com) provides an array of block copolymers as well as reactive intermediates including polyvivo AI20. Recently researchers utilized PolyVivo AI20 (Mal-PEG-PLGA) along with mPEG-PLGA from PolySciTech to generate a nanoparticle sytem which they then conjugated to thiol endcapped polyaspartic acid to form a targeted system for bone-tissue targeting.  This system was validated against osteoblast cells/stem cells as well as ex-vivo tibia sections to show that it provided a non-cytotoxic method for specifically targeting bone tissue.  This method could be used to aid delivery of drugs specifically to bone tissue for treatment of bone diseases. Read more: Jiang, Tao, Xiaohua Yu, Erica J. Carbone, Clarke Nelson, Ho Man Kan, and Kevin W-H. Lo. “Poly aspartic acid peptide-linked PLGA based nanoscale particles: Potential for bone-targeting drug delivery applications.” International Journal of Pharmaceutics (2014). http://www.sciencedirect.com/science/article/pii/S0378517314006334

 

“Abstract: Delivering drugs specifically to bone tissue is very challenging due to the architecture and structure of bone tissue. Poly(lactic-co-glycolic acid) (PLGA)-based nanoparticles (NPs) hold great promise for the delivery of therapeutics to bone tissue. The goal of the present research was to formulate a PLGA-based NP drug delivery system for bone tissue exclusively. Since poly-aspartic acids (poly-Asp) peptide sequence has been shown to bind to hydroxyapatite (HA), and has been suggested as a molecular tool for bone-targeting applications, we fabricated PLGA-based NPs linked with poly-Asp peptide sequence. Nanoparticles made of methoxy – poly(ethylene glycol) (PEG)-PLGA and maleimide-PEG-PLGA were prepared using a water-in-oil-in-water double emulsion and solvent evaporation method. Fluorescein isothiocyanate (FITC)-tagged poly-Asp peptide was conjugated to the surface of the nanoparticles via the alkylation reaction between the sulfhydryl groups at the N-terminal of the peptide and the C double bond; length as C=C double bond of maleimide at one end of the polymer chain to form thioether bonds. The conjugation of FITC-tagged poly-Asp peptide to PLGA NPs was confirmed by NMR analysis and fluorescent microscopy. The developed nanoparticle system is highly aqueous dispersible with an average particle size of ∼80 nm. In vitro binding analyses demonstrated that FITC-poly-Asp NPs were able to bind to HA gel as well as to mineralized matrices produced by human mesenchymal stem cells and mouse bone marrow stromal cells. Using a confocal microscopy technique, an ex vivo binding study of mouse major organ ground sections revealed that the FITC-poly-Asp NPs were able to bind specifically to the bone tissue. In addition, proliferation studies indicated that our FITC-poly-Asp NPs did not induce cytotoxicity to human osteoblast-like MG63 cell lines. Altogether, these promising results indicated that this nanoscale targeting system was able to bind to bone tissue specifically and might have a great potential for bone disease therapy in clinical applications. Keywords: Nanoparticles; Targeted drug delivery; Peptides; Bone diseases”

Jiang, 2014 polyscitech PASP-PEG-PLGA bone tissue

New PEG-PLA-FKR648 from PolySciTech for NIR tracking of micelles

PolySciTech (www.polyscitech.com) provides a wide variety of fluorescently conjugated polyesters such as PLGA-FITC and others. We are proud to announce the development of our first fluorescently conjugated block copolymer. The block copolymer, PolyVivo AV17, is same size and configuration as our popular AK09 (mPEG-P(DL)La 2000-2200 Da) but has a NIR fluorescent dye (Flamma Fluor FKR-648) conjugated to the P(DL)La alcohol terminus via a dichlorotriazine linkage.  Read more about appropriate NIR imaging conditions for this type of dye here. Full-Text: Hollis, Christin P., Heidi L. Weiss, B. Mark Evers, Richard A. Gemeinhart, and Tonglei Li. “In Vivo Investigation of Hybrid Paclitaxel Nanocrystals with Dual Fluorescent Probes for Cancer Theranostics.” Pharmaceutical research 31, no. 6 (2014): 1450-1459. http://www.uic.edu/labs/bpslab/PDF/PharmRes_31_1450_2014.pdf

“Abstract: To develop novel hybrid paclitaxel (PTX) nanocrystals, in which bioactivatable (MMPSense® 750 FAST) and near infrared (Flamma Fluor® FPR-648) fluorophores are physically incorporated, and to evaluate their anticancer efficacy and diagnostic properties in breast cancer xenograft murine model. The pure and hybrid paclitaxel nanocrystals were prepared by an anti-solvent method, and their physical properties were characterized. The tumor volume change and body weight change were evaluated to assess the treatment efficacy and toxicity. Bioimaging of treated mice was obtained non-invasively in vivo.The released MMPSense molecules from the hybrid nanocrystals were activated by matrix metalloproteinases (MMPs) in vivo, similarly to the free MMPSense, demonstrating its ability to monitor cancer progression. Concurrently, the entrapped FPR-648 was imaged at a different wavelength. Furthermore, when administered at 20 mg/kg, the nanocrystal formulations exerted comparable efficacy as Taxol®, but with decreased toxicity. Hybrid nanocrystals that physically integrated two fluorophores were successfully prepared from solution. Hybrid nanocrystals were shown not only exerting antitumor activity, but also demonstrating the potential of multi-modular bioimaging for diagnostics.”

PolySciTech AV17

New PLGA-PEG-azide/bromoacetamide/iodoacetamide products from PolySciTech for custom ligand conjugation

PolySciTech (www.polyscitech.com) provides a wide variety of block copolymers as well as reactive intermediates.  A variety of new intermediates are now available from PolySciTech based on the PLGA-PEG diblock configuration and possessing a variety of reactive endcaps including iodoacetamide (PolyVivo AI83), bromoacetamide (PolyVivo AI84), and azide (PolyVivo AI85). Read more about the conjugation chemistry which can be used to couple these to ligands here: Roberts, M. J., M. D. Bentley, and J. M. Harris. “Chemistry for peptide and protein PEGylation.” Advanced drug delivery reviews 54, no. 4 (2002): 459-476. Full-Text: http://www.creativepegworks.com/chemistry_for_peptide_and_protein_pegylation.pdf

“Abstract: Poly(ethylene glycol) (PEG) is a highly investigated polymer for the covalent modification of biological macromolecules and surfaces for many pharmaceutical and biotechnical applications. In the modification of biological macromolecules, peptides and proteins are of extreme importance. Reasons for PEGylation (i.e. the covalent attachment of PEG) of peptides and proteins are numerous and include shielding of antigenic and immunogenic epitopes, shielding receptor-mediated uptake by the reticuloendothelial system (RES), and preventing recognition and degradation by proteolytic enzymes. PEG conjugation also increases the apparent size of the polypeptide, thus reducing the renal filtration and altering biodistribution. An important aspect of PEGylation is the incorporation of various PEG functional groups that are used to attach the PEG to the peptide or protein. In this paper, we review PEG chemistry and methods of preparation with a particular focus on new (second-generation) PEG derivatives, reversible conjugation and PEG structures. Keywords PEGylation; PEG-protein; PEG conjugation; PEG chemistry”

PolySciTech Precursors