Monthly Archives: October 2015

Block PEG-PLGA and Maleimide-PEG-PLGA investigated for treatment of periodontitis

PolySciTech division of Akina, Inc. (www.polyscitech.com) provides a wide array of biodegradable block copolymers including mPEG-PLA and Mal-PEG-PLA. Recently researchers used these types of polymers to generate RGD (arginine-glycine-aspartic acid a general binding domain for many cell types) decorated nanoparticles for delivery of minocycline to bacteria for treatment of periodontal infection. Read more: Yao, Wenxin, Peicheng Xu, Jingjing Zhao, Li Ling, Xiaoxia Li, Bo Zhang, Nengneng Cheng, and Zhiqing Pang. “RGD functionalized polymeric nanoparticles targeting periodontitis epithelial cells for the enhanced treatment of periodontitis in dogs.” Journal of colloid and interface science 458 (2015): 14-21. (http://www.sciencedirect.com/science/article/pii/S0021979715300515)

“Abstract: Long term retention of antimicrobials with effective drug concentration in gingival crevicular fluid (GCF) is of vital importance for the treatment of chronic periodontitis. In this study, a novel epithelial cell-targeting nanoparticle drug delivery system by conjugating minocycline-loaded poly(ethylene glycol)–poly(lactic acid) (PEG–PLA) nanoparticles (NP-MIN) with RGD peptide were developed and administrated locally for targeting periodontitis epithelial cells and enhancing the treatment of periodontitis in dogs. Biodegradable NP-MIN was made with an emulsion/solvent evaporation technique. RGD peptide was conjugated to the surface of nanoparticles via Maleimide group reaction with hydrosulfide in RGD peptide (RGD-NP-MIN). Transmission electron microscopy examination and dynamic light scattering results revealed that RGD-NP-MIN had a sphere shape, with a mean diameter around 106 nm. In vitro release of minocycline from RGD-NP-MIN showed that RGD modification did not change the remarkable sustained releasing characteristic of NP-MIN. To elucidate the interaction of RGD-NP and epithelial cells, RGD-NP binding, uptake and cellular internalization mechanisms by calu-3 cells were investigated. It was shown RGD modification significantly enhanced nanoparticles binding and uptake by Calu-3 cells, and RGD-NP uptake was an energy-dependent process through receptor-mediated endocytosis. Both clathrin-associated endocytosis and caveolae-dependent endocytosis pathway were involved in the RGD-NP uptake, and the intracellular transport of RGD-NP was related to lysosome and Golgi apparatus. Finally, in vivo pharmacokinetics of minocycline in the periodontal pockets and anti-periodontitis effects of RGD-NP-MIN on periodontitis-bearing dogs were evaluated. After local administration of RGD-NP-MIN, minocycline concentration in gingival crevicular fluid decreased slowly and maintained an effective drug concentration for a longer time than that of NP-MIN. Anti-periodontitis effects demonstrated that RGD-NP-MIN could significantly decrease symptoms of periodontitis, which was better than any other control group. These findings suggested that these epithelial cell-targeting nanoparticles offered a novel and effective local delivery system for the treatment of periodontitis. Keywords: RGD peptide; Polymeric nanoparticles; Targeting periodontitis epithelial cells; Minocycline; Local delivery”

New products from PolySciTech PLGA-histidine; fluorescent, biodegradable thermogels

PolySciTech division of Akina, Inc. provides a wide variety of biodegradable polymers and research products. Recently we have just added three new products. The first of which is PLGA-histidine methyl ester endcap (PolyVivo AI117). This polymer has the histidine unit which can allow for reaction with Iodine-125 which is a radio-label allowing the polymer to be traced by radio-based techniques. In addition to this, two fluorescent derivatives of thermogelling PolyVivo AK097 are available including AV025 which has a near infra-red conjugate dye and AV026 which has a FITC region conjugate dye. This allows for subsequent thermogels to be tracked by microscopy and other fluorescent techniques. Find out more at www.polyscitech.com.

PLGA-PEG-PLGA thermogel from PolySciTech investigated for macular degeneration treatment

PolySciTech division of Akina, Inc. (www.polyscitech.com) provides many polymers including thermogelling PLGA-PEG-PLGA triblock copolymers such as PolyVivo AK024. Recently this polymer was used by researchers at University of South Florida to deliver nanoparticles incorporating loteprednol etabonate, a drug which is used to treat AMD, as an ocular injection. They found that the system was non-cytotoxic and significantly reduced VEGF expression. Read more: Hirani, Anjali, Yong W Lee, Yashwant Pathak, and Vijaykumar Sutariya. “Efficacy of Loteprednol Etabonate Drug Delivery System in Suppression of in vitro Retinal Pigment Epithelium Activation.” Pharmaceutical Nanotechnology 2, no. 4 (2014): 208-216. http://www.ingentaconnect.com/content/ben/pnt/2014/00000002/00000004/art00006

“Abstract: Choroidal neovascularization (CNV) is the growth of abnormal blood vessels in the choroid layer of the eye; it is a pathophysiological characteristic of wet age-related macular degeneration (AMD). Current clinical treatment utilizes frequent intravitreal injections, which can result in retinal detachment and increased ocular pressure. The purpose of the current study is to develop a novel drug delivery system of loteprednol etabonateencapsulated PEGylated PLGA nanoparticles incorporated into the PLGA-PEG-PLGA thermoreversible gel for treatment of AMD. The proposed drug delivery system was characterized for drug release, cytotoxicity studies and vascular endothelial growth factor (VEGF) suppression efficacy studies using ARPE-19 cells. The nanoparticles showed uniform size distribution with mean size of 168.60±23.18 nm and exhibited sustained drug release. Additionally, the proposed drug delivery system was non-cytotoxic to ARPE-19 cells and significantly reduced VEGF expression as compared to loteprednol etabonate solution. These results suggest the proposed drug delivery system can be used for further work in an animal model of experimental AMD with reduced intravitreal administration frequency. Keywords: Choroidal neovascularization; PLGA nanoparticles; VEGF; loteprednol etabonate; thermoreversible gel”

PolySciTech PLGA-Fluorescein (AV001) used in investigation of PLGA-Chitosan based paclitaxel delivery system

PolySciTech division of Akina, Inc. (www.polyscitech.com) provides a wide array of biodegradable block copolymers and specialty polymers. One of the PolyVivo polymer categories is fluorescently conjugated PLGAs. These are useful for co-formulation with PLGA nanoparticles so that the nanoparticle system, as a whole, is fluorescent.  Unlike loose dye, the conjugated fluorescent-PLGA is entrapped in the nanoparticle and follows it wherever it goes without leaching away. This allows the nanoparticles to be observed under a fluorescent microscope or other fluorescent imaging system so that their motion can be tracked. Recently, researchers at Purdue University utilized PolyVivo AV001 (PLGA-fluorescein 7kDa) to track PLGA-chitosan nanoparticles as part of a system to deliver chemotherapeutic paclitaxel. Read more: Abouelmagd, Sara A., Youn Jin Ku, and Yoon Yeo. “Low molecular weight chitosan-coated polymeric nanoparticles for sustained and pH-sensitive delivery of paclitaxel.” Journal of drug targeting 23, no. 7-8 (2015): 725-735. http://www.tandfonline.com/doi/abs/10.3109/1061186X.2015.1054829

“Abstract: Low molecular weight chitosan (LMWC) is a promising polymer for surface modification of nanoparticles (NPs), which can impart both stealth effect and electrostatic interaction with cells at mildly acidic pH of tumors. We previously produced LMWC-coated NPs via covalent conjugation to poly(lactic-co-glycolic) acid (PLGA-LMWC NPs). However, this method had several weaknesses including inefficiency and complexity of the production as well as increased hydrophilicity of the polymer matrix, which led to poor drug release control. Here, we used the dopamine polymerization method to produce LMWC-coated NPs (PLGA-pD-LMWC NPs), where the core NPs were prepared with PLGA that served best to load and retain drugs and then functionalized with LMWC via polydopamine layer. The PLGA-pD-LMWC NPs overcame the limitations of PLGA-LMWC NPs while maintaining their advantages. First of all, PLGA-pD-LMWC NPs attenuated the release of paclitaxel to a greater extent than PLGA-LMWC NPs. Moreover, PLGA-pD-LMWC NPs had a pH-dependent surface charge profile and cellular interactions similar to PLGA-LMWC NPs, enabling acid-specific NP–cell interaction and enhanced drug delivery to cells in weakly acidic environment. Although the LMWC layer did not completely prevent protein binding in serum solution, PLGA-pD-LMWC NPs showed less phagocytic uptake than bare PLGA NPs.”

PLLA from PolySciTech used for bone scaffold application research

PolySciTech division of Akina, Inc (www.polyscitech.com) provides a wide array of biodegradable polymers including poly(L)lactide (PLLA). This is a highly crystalline and mechanically strong polymer which has good properties for load-bearing applications such as bone scaffolds. Recently, researchers combined PLLA from Polyscitech with hydroxyapatite to form a conventional bone-scaffold and tested against a novel N-methyldiethanolamine/poly(1,8-octanediol citrate) based scaffold. Read more: Tang, Jiajun, Jinshan Guo, Zhen Li, Cheng Yang, Denghui Xie, Jian Chen, Shengfa Li et al. “A fast degradable citrate-based bone scaffold promotes spinal fusion.” Journal of Materials Chemistry B 3, no. 27 (2015): 5569-5576. http://pubs.rsc.org/en/content/articlehtml/2015/tb/c5tb00607d

“Abstract: It is well known that high rates of fusion failure and pseudoarthrosis development (5–35%) are concomitant in spinal fusion surgery, which was ascribed to the shortage of suitable materials for bone regeneration. Citrate was recently recognized to play an indispensable role in enhancing osteoconductivity and osteoinductivity, and promoting bone formation. To address the material challenges in spinal fusion surgery, we have synthesized mechanically robust and fast degrading citrate-based polymers by incorporating N-methyldiethanolamine (MDEA) into clickable poly(1,8-octanediol citrates) (POC-click), referred to as POC-M-click. The obtained POC-M-click were fabricated into POC-M-click–HA matchstick scaffolds by forming composites with hydroxyapatite (HA) for interbody spinal fusion in a rabbit model. Spinal fusion was analyzed by radiography, manual palpation, biomechanical testing, and histological evaluation. At 4 and 8 weeks post surgery, POC-M-click–HA scaffolds showed optimal degradation rates that facilitated faster new bone formation and higher spinal fusion rates (11.2 ± 3.7, 80 ± 4.5 at week 4 and 8, respectively) than the poly(L-lactic acid)–HA (PLLA–HA) control group (9.3 ± 2.4 and 71.1 ± 4.4) (p < 0.05). The POC-M-click–HA scaffold-fused vertebrates possessed a maximum load and stiffness of 880.8 ± 14.5 N and 843.2 ± 22.4 N mm−1, respectively, which were also much higher than those of the PLLA–HA group (maximum: 712.0 ± 37.5 N, stiffness: 622.5 ± 28.4 N mm−1, p < 0.05). Overall, the results suggest that POC-M-click–HA scaffolds could potentially serve as promising bone grafts for spinal fusion applications.”

PLGA-PEG-PLGA (AK097) thermogel from PolySciTech used as adjuvant to improve vaccine efficacy

PolySciTech division of Akina, Inc. (www.polyscitech.com) provides a wide array of biodegradable block copolymers including thermogelling PLGA-PEG-PLGA block copolymers. Recently, PolySciTech’s thermogelling PolyVivo AK097, was used by researchers at Auburn University for the co-administration of a phage-based vaccine as an adjuvant. Impressively, after 4-8 weeks this co-administration of phage with thermogel yielded a statistically significant 2.5-3 fold increase in the immune response (as measured by ELISA) relative to a control delivery of the phage itself without the thermogel (Fig 6A). This indicates that the thermogel has promise as an adjuvant to boost the immune response towards vaccines and improve therapeutic efficacy of these vaccines. Read more: Samoylov, Alexandre, Anna Cochran, Bettina Schemera, Michelle Kutzler, Caitlin Donovan, Valery Petrenko, Frank Bartol, and Tatiana Samoylova. “Humoral immune responses against gonadotropin releasing hormone elicited by immunization with phage-peptide constructs obtained via phage display.” Journal of Biotechnology (2015). http://www.sciencedirect.com/science/article/pii/S0168165615301498

“Abstract: Phage display is based on genetic engineering of phage coat proteins resulting in fusion peptides displayed on the surface of phage particles. The technology is widely used for generation of phages with novel characteristics for numerous applications in biomedicine and far beyond. The focus of this study was on development of phage-peptide constructs that stimulate production of antibodies against gonadotropin releasing hormone (GnRH). Phage-peptide constructs that elicit production of neutralizing GnRH antibodies can be used for anti-fertility and anti-cancer applications. Phage-GnRH constructs were generated via selection from a phage display library using several types of GnRH antibodies as selection targets. Such phage constructs were characterized for sequence similarities to GnRH peptide and frequency of their occurrence in the selection rounds. Five of the constructs with suitable characteristics were tested in mice as a single dose 5 × 1011 virions (vir) vaccine and were found to be able to stimulate production of GnRH-specific antibodies, but not to suppress testosterone (indirect indicator of GnRH antibody neutralizing properties). Next, one of the constructs was tested at a higher dose of 2 × 1012 vir per mouse in combination with a poly(lactide- co -glycolide) (PLGA)-based adjuvant. This resulted in multifold increase in GnRH antibody production and significant reduction of serum testosterone, indicating that antibodies produced in response to the phage-GnRH immunization possess neutralizing properties. To achieve optimal immune responses for desired applications, phage-GnRH constructs can be modified with respect to flanking sequences of GnRH-like peptides displayed on phage. Anticipated therapeutic effects also might be attained using optimized phage doses, a combination of several constructs in a single treatment, or application of adjuvants and advanced phage delivery systems. Keywords: filamentous phage; phage display; gonadotropin releasing hormone; GnRH antibodies; contraception; hormone-dependent reproductive cancers Abbreviations: cfu, colony forming unit; FSHR, follicle-stimulating hormone receptor; GnRH, gonadotropin releasing hormone; GnRHR, gonadotropin releasing hormone receptor; PLGA, poly(lactide- co -glycolide); PEG, polyethylene glycol; vir, virion”

Poly(D)Lactide now available from PolySciTech

PolySciTech Division of Akina, Inc. (www.polyscitech.com) provides a wide array of biodegradable polymers and block copolymers. This now includes pure poly(D)lactide (e.g. PolyVivo AP157) which is a useful polymer for forming stereocomplexes with poly(L)lactide. Read more about this here: Xiong, Zujiang, Xiuqin Zhang, Rui Wang, Sicco de Vos, Ruyin Wang, Cornelis AP Joziasse, and Dujin Wang. “Favorable formation of stereocomplex crystals in poly (l-lactide)/poly (d-lactide) blends by selective nucleation.” Polymer 76 (2015): 98-104. http://www.sciencedirect.com/science/article/pii/S0032386115301956

“Abstract: An aryl amide derivative (TMB-5) was used to nucleate the poly(l-lactide)/poly(d-lactide) (PLLA/PDLA) blend for the first time. The effect of TMB-5 nucleating agent on the crystallization behavior of PLLA/PDLA blend was systematically investigated. The selective nucleation of stereocomplex (sc) crystals by incorporation of TMB-5 was realized under appropriate crystallization conditions. During the cooling process, various morphology of TMB-5 due to its partial or complete dissolution in the PLLA/PDLA blend melt was observed. Furthermore, an sc crystals layer on the lateral surface of TMB-5 was found. Upon cooling a PLLA/PDLA blend from 260 °C at rates between 2 and 100 °C/min, 0.5 wt% addition of TMB-5 induced a single melting peak of sc crystals and no homocrystallization was observed in the subsequent DSC heating scan. The melting temperature of the sc crystals was found to decrease in the presence of TMB-5 from 230 to ca. 200 °C, which is still 20 °C higher than that of PLLA homopolymer. The results suggest that the supramolecular structure of the nucleating agent plays an important role in the crystallization of the PLLA/PDLA blend. The difference in solubility and recrystallization ability of TMB-5 in polymer melt results in the variation of crystallization behavior of PLLA/PDLA blend, which is correlated with the concentration of TMB-5 and crystallization conditions including the final melting temperature, annealing time and cooling rate. Keywords: Stereo-complex crystals; Supramolecular structure; Nucleating agent”

SPOOKY PolySciTech Discount on research products

PolySciTech division of Akina, Inc. (www.polyscitech.com) provides a wide array of research products including biodegradable block copolymers, reactive intermediates, PLGA’s, functionalized PEG’s, fluorescently conjugated polymers, and thermogelling products for cell-growth. In celebration of Halloween, we are extending a spooky good deal for these products. Use the coupon code “SPOOKY2015” to take 5% off any order of stock products over $100 placed online from October 7th through the 31st.

SPIO-loaded PLGA-RGD nanoparticles used for dual cancer targeting by integrin binding and magnetism.

PolySciTech Division of Akina, Inc. (www.polyscitech.com) provides a wide array of polymers including PLGA and related activated precursors such as PLGA-NHS. These kinds of polymers have been utilized to develop a theranostic targeted nanoparticle. Theranostics is a relatively new approach to cancer in which the targeting strategy serves to both diagnose the cancer (by fluorescence or radio-opacity) as well as treat cancer (by delivery of chemotherapeutic agents). Researchers in Belgium recently developed such targeted nanoparticles by using two different targeting strategies. The first of which was to conjugate RGD labelling peptide onto the exterior of the PLGA nanoparticle so that it can preferentially bind to cancer cells by targeting the αvβ3 integrin, an integrin involved in angiogenesis that is overexpressed on cancer cells. Additionally the particles were loaded with super-paramagnetic iron oxide (SPIO) which renders the particles magnetic. By simply placing a magnet near the tumor, the particles can be attracted to the magnet. SPIO serves another diagnostic purpose in that it serves as a MRI contrast agent allowing the tumor to be visualized by this technique. The particles were also loaded with chemotherapeutic paclitaxel and the system analyzed extensively. You can read about this work here: Danhier, Fabienne, Pierre Danhier, Nathalie Schleich, Chrystelle Po, Sophie Laurent, Pierre Sibret, Christine Jeroˆme, Vincent Poucelle, Bernard Gallez, and Veronique Preat. “Tumor Targeting by RGD-Grafted PLGA-Based Nanotheranostics Loaded with Paclitaxel and Superparamagnetic Iron Oxides.” (2015). http://link.springer.com/protocol/10.1007/7653_2015_43

 

“Abstract: Theranostic nanoparticles have the potential to revolutionize cancer diagnosis and therapy. Many groups have demonstrated differential levels of tumor growth between tumors treated by targeted or untargeted nanoparticles; however, only few have shown in vivo efficacy in both therapeutic and diagnostic approach. Herein, we first develop and characterize dual-paclitaxel (PTX)/superparamagnetic iron oxide (SPIO)-loaded PLGA-based nanoparticles grafted with the RGD peptide, for a theranostic purpose. Second, we compare in vivo different strategies in terms of targeting capabilities: (1) passive targeting via the EPR effect, (2) active targeting of αvβ3 integrin via RGD grafting, (3) magnetic guidance via a magnet placed on the tumor, and (4) the combination of the magnetic guidance and the active targeting of αvβ3 integrin. In this chapter, we present the general flowchart applied for this project: (1) the polymer and SPIO synthesis, (2) the physicochemical characterization of the nanoparticles, (3) the magnetic properties of the nanoparticles, and (4) the in vivo evaluation of the nanoparticles for their therapeutic and diagnosis purposes. We employ the electron spin resonance spectroscopy and magnetic resonance imaging to both quantify and visualize the accumulation of theranostic nanoparticles into the tumors. Keywords: PLGA-nanoparticles SPIO Paclitaxel Cancer therapy Magnetic resonance imaging Tumor targeting Nanotheranostic”

Encapsulation Efficiency Determination method of mPEG-PLA nanoparticles

PolySciTech Division of Akina, Inc. (www.polyscitech.com) provides a wide array of biodegradable block copolymers such as mPEG-PLA. Often these polymers are used for generating nanoparticles for drug release. A question I often receive is: how does one determine encapsulation efficiency for the drug loaded in the nanoparticles? It is typically not advised to load the nanoparticles directly into the HPLC. The answer depends on the pharmaceutical ingredient but typically requires disrupting the nanoparticles by dissolving them in a good polymer solvent first (such as dichloromethane) and then extracting the drug into a solvent which is appropriate for HPLC testing. An example is shown below:

Example encapsulation efficiency protocol for paclitaxel in mPEG-PLA (Y. Dong, S.-S. Feng / Biomaterials 25 (2004) 2843–2849):

“Two ml particle suspension was freeze-dried and the drug encapsulated in the lyophilized particles was determined using HPLC (Agilent LC 1100). Briefly, 3 mg particles were dissolved in 1 ml DCM under vigorous vortexing. This solution was transferred to 5 ml of the mixture of 50/50 (v/v) acetonitrile and water. The nitrogen was introduced to evaporate dicholoromethane and a clear solution was obtained for HPLC analysis. The mobile phase of HPLC was composed of acetonitrile and water of 50/50 (v/v). The measurement was performed triplicate. The EE was expressed as the percentage of the drug loaded in the final product.”

You can read more about this as well as other aspects of mPEG-PLA drug loading and delivery here: Dong, Yuancai, and Si-Shen Feng. “Methoxy poly (ethylene glycol)-poly (lactide)(MPEG-PLA) nanoparticles for controlled delivery of anticancer drugs.” Biomaterials 25, no. 14 (2004): 2843-2849. http://www.sciencedirect.com/science/article/pii/S014296120300797X

“Abstract: Methoxy poly(ethylene glycol)-poly(lactide) copolymer (MPEG-PLA) was synthesized and used to make nanoparticles by the nanoprecipitation method for clinical administration of antineoplastic drugs. Paclitaxel was used as a prototype drug due to its excellent efficacy and commercially great success. The size and size distribution, surface morphology, surface charge and surface chemistry of the paclitaxel-loaded nanoparticles were then investigated by laser light scattering, atomic force microscopy, zeta-potential analyzer and X-ray photoelectron spectroscopy (XPS). The drug encapsulation efficiency (EE) and in vitro release profile were measured by high-performance liquid chromatography. The effects of various formulation parameters were evaluated. The prepared nanoparticles were found of spherical shape with size less than 100 nm. Zeta potential measurement and XPS analysis demonstrated the presence of PEG layer on the particle surface. Viscosity of the organic phase was found to be one of the main process factors for the size determination. The EE was found to be greatly influenced by the drug loading. The drug release pattern was biphasic with a fast release rate followed by a slow one. The particle suspension exhibited good steric stability in vitro. Such a nanoparticle formulation of paclitaxel can be expected to have long-circulating effects in circulation. Keywords: AFM (atomic force microscopy); Biodegradable polymers; Chemotherapy; Taxanes; XPS (X-ray photoelectron spectroscopy)”