Monthly Archives: July 2015

PolySciTech PLGA-Fluorescein used for tracking nanoparticles as part of carboplatin based brain cancer therapy

PolySciTech (www.polyscitech.com) provides a wide range of polymers including PLGA-fluorescein conjugates. The fluorescein endcap absorbs blue colored light with a wavelength around 490 nm and then re-emits green colored light around 525nm wavelength. The practical application of this is that it allows for the PLGA formulation to be imaged using a fluorescent microscope or other device so that nanoparticles generated using this PLGA can be tracked as they flow through various systems and are uptaken into cells. Recently researchers from Bristol University, University of Bath, and Renishaw Plc did precisely this by combining AV01 and AV04 (PLGA-Fluorescein) along with unstained PLGA to generate carboplatin, a chemotherapy agent, loaded nanoparticles which could be tracked by fluorescence. They then tested these in cell culture and rat/porcine models along with a convection enhanced delivery system to improve delivery of carboplatin to the tumors. Read more: Arshad, Azeem, Bin Yang, Alison S. Bienemann, Neil U. Barua, Marcella J. Wyatt, Max Woolley, Dave E. Johnson, Karen J. Edler, and Steven S. Gill. “Convection-Enhanced Delivery of Carboplatin PLGA Nanoparticles for the Treatment of Glioblastoma.” PLOS ONE 10, no. 7 (2015): e0132266. http://dx.plos.org/10.1371/journal.pone.0132266 You can see all articles referencing PolySciTech products here (https://akinainc.com/polyscitech/products/polyvivo/referenced_by.php)

 

“Abstract: We currently use Convection-Enhanced Delivery (CED) of the platinum-based drug, carboplatin as a novel treatment strategy for high grade glioblastoma in adults and children. Although initial results show promise, carboplatin is not specifically toxic to tumour cells and has been associated with neurotoxicity at high infused concentrations in pre-clinical studies. Our treatment strategy requires intermittent infusions due to rapid clearance of carboplatin from the brain. In this study, carboplatin was encapsulated in lactic acid-glycolic acid copolymer (PLGA) to develop a novel drug delivery system. Neuronal and tumour cytotoxicity were assessed in primary neuronal and glioblastoma cell cultures. Distribution, tissue clearance and toxicity of carboplatin nanoparticles following CED was assessed in rat and porcine models. Carboplatin nanoparticles conferred greater tumour cytotoxicity, reduced neuronal toxicity and prolonged tissue half-life. In conclusion, this drug delivery system has the potential to improve the prognosis for patients with glioblastomas.”

Nanoparticle generation protocol: “Carboplatin NP were produced using the double—emulsion method (W1/O1/W2). Briefly, 60 mg Poly (lactide-co-glicolide) (PLGA) (polymers with a 1:1 co-polymerization ratio ester ended (RG504 Mw 38-54KDa- Sigma-Aldrich, UK), acid ended (RG504H, Mw 38-54KDa—Sigma-Aldrich, UK) and poly(lactic acid) (PLA R203H Mw 18-24kDa- Sigma-Aldrich, UK) was dissolved in 2ml dichloromethane /ethyl acetate (DCM/EA) (both Sigma-Aldrich, UK) (2:8 V/V, O1 phase) and 0.7ml aqueous solution of carboplatin (10 mg/ml, W1 phase) (Accord Healthcare Limited, UK) was emulsified in the PLGA solution using a micro-tip probe sonicator (Model VC 600, Sonics & materials Inc., UK) set at level 4 for 3 minutes. Level 4 corresponded to 20 kHz at 45 W cm-2, and had been calibrated previously. Encapsulation and release of aqueous components from sonochemically produced protein microspheres.

The primary (W1/O1) emulsion was transferred into 40 ml of Polyvinyl alcohol- Mw 20 KDa (PVA) (MP Biomedicals, USA). 2.5% solution (W2 phase) and the mixture was probe sonicated at level 4 for 5 minutes. The W1/O1/W2 emulsion was agitated by a magnetic stirrer uncovered overnight at room temperature to remove the organic solvent. In order to obtain particles with the desired diameter, the particle solution was treated by centrifugation (Centrifuge 5804R, Eppendorf, UK) at 9000 rpm for 15 minutes which caused the large particles to form a pellet while the smaller particles remained in the supernatant. The pellet of large nanoparticles was discarded while nanoparticles in the supernatant were collected and washed by ultracentrifugation (40000rpm for 20 minutes, Motor type 70Ti/70.1Ti, L-80 ultracentrifuge, Beckman Coulter, UK). This pellet of nanoparticles was re-suspended in water, freeze-dried and stored at -20°C for further usage. For fluorescent carboplatin nanoparticles (fluorescein carboplatin NP), PLGA was substituted with the mixture of PLGA (Mw 38-54KDa) and PLGA-Fluorescein end cap copolymer (Mw 7KDa and 30K-40K, purchased from Polyscitech, AKINA, USA) with the weight ratio of 9:1, and processed as described.”

mPEG-PLGA used for breast cancer therapy

PolySciTech (www.polyscitech.com) provides a wide array of block copolymers including mPEG-PLGA. Recently this type of polymer was used for delivering doxorubicin as a breast cancer treatment. Read more: Alibolandi, Mona, Fatemeh Sadeghi, Khalil Abnous, Fatemeh Atyabi, Mohammad Ramezani, and Farzin Hadizadeh. “The chemotherapeutic potential of doxorubicin-loaded PEG-b-PLGA nanopolymersomes in mouse breast cancer model.” European Journal of Pharmaceutics and Biopharmaceutics (2015). http://www.sciencedirect.com/science/article/pii/S0939641115002945

“Abstract: Vesicles of mPEG-PLGA block copolymer were developed to deliver a therapeutic quantity of doxorubicin (DOX) for breast cancer treatment. The DOX-loaded nanoparticles (NPs) were prepared by the pH-gradient method and then evaluated in terms of morphology, size, DOX encapsulation efficiency and in vitro drug release mechanism. The PEG-PLGA nanopolymersomes were 134 ± 1.2 nm spherical NPs with a narrow size distribution (PDI = 0.121). DOX was entrapped in mPEG-PLGA nanopolymersomes with an encapsulation efficiency and a loading content of 91.25 ± 4.27% and 7.3 ± 0.34%, respectively. The DOX-loaded nanopolymersomes were found to be stable, demonstrating no significant change in particle size and encapsulation efficiency (EE%) during the 6-month storage period of the lyophilized powder at 4 °C. The nanopolymersomes sustained the release of DOX. In cytotoxicity studies of 4T1 cell line samples, free DOX showed a higher cytotoxicity (IC50 = 1.76 μg/mL) than did DOX-loaded nanopolymersomes (15.82 μg/mL) in vitro. In order to evaluate the antitumor efficacy and biodistribution of DOX-loaded nanopolymersomes, murine breast tumors were established on the BALB/c mice, and in vivo studies were performed. The obtained results demonstrated that the prepared drug delivery system was highly effective against a murine breast cancer tumor model and successfully accumulated in the tumor site through an enhanced permeation and retention mechanism. In vivo studies also proved that DOX-loaded nanopolymersomes are stable in blood circulation and could be considered a promising and effective DOX delivery system for breast cancer treatment.

Highlights:Vesicles of mPEG-PLGA block copolymer were developed to deliver therapeutic quantity of doxorubicin for breast cancer treatment. The doxorubicin loaded nanoparticles were fabricated by pH gradient method. The PEG-PLGA nanopolymersomes were 134 ± 1.2 nm spherical nanoparticles with narrow size distribution (PDI = 0.121). Doxorubicin was entrapped in mPEG-PLGA nanopolymersomes with encapsulation efficiency and loading content of 91.25 ± 4.27%. The prepared drug delivery system was highly effective against murine breast cancer tumor model. Keywords: Doxorubicin; Breast cancer; Nanopolymersome; Drug delivery; Breast cancer; 4T1”

PolySciTech Mal-PEG-PLGA/mPEG-PLGA along with scorpion venom used for brain tumor diagnostic-therapy application

PolySciTech (www.polyscitech.com) provides a wide array of biodegradable block copolymers and reactive intermediates. Recently, researchers at the University of Nevada utilized PolySciTech mPEG-PLGA (PolyVivo AK051) and Mal-PEG-PLGA (Polyvivo AI075) to generate mixed micelles. These micelles were loaded with quantum dots, metallic based nanoparticles that are easily detected in the body and serve well as an imaging contrast agent, and had chlorotoxin, a component derived from scorpion venom which has shown a preference for binding to brain cancer cells, conjugated to the exterior of the micelle using a michael’s type thiol-maleimide reaction. The micelles were then introduced to cells and were observed to be specifically internalized by the U-87 brain tumor cells.  Read more: Chen, Siqi, Mojtaba Ahmadiantehrani, Nelson Publicover, Kenneth Hunter, and Xiaoshan Zhu. “Thermal Decomposition Based Synthesis of Ag-In-S/ZnS Quantum Dots and Their Chlorotoxin-Modified Micelles for Brain Tumor Cell Targeting.” RSC Advances (2015). http://pubs.rsc.org/en/content/articlehtml/2015/ra/c5ra11250h

“Abstract: Cadmium-free silver-indium-sulfide (Ag-In-S or AIS) chalcopyrite quantum dots (QDs) as well as their core–shell structures (AIS/ZnS QDs) are being paid significant attention in biomedical applications because of their low toxicity and excellent optical properties. Here we report a simple and safe synthetic system to prepare high quality AIS and AIS/ZnS QDs using thermal decomposition. The synthetic system simply involves heating a mixture of silver acetate, indium acetate, and oleic acid in dodecanethiol at 170 °C to produce AIS QDs with a 13% quantum yield (QY). After ZnS shell growth, the produced AIS/ZnS QDs achieve a 41% QY. To facilitate phase transfer and bioconjugation of AIS/ZnS QDs for cellular imaging, these QDs were loaded into the core of PLGA–PEG (5kDa : 5kDa) based micelles to form AIS/ZnS QD-micelles. Cellular imaging studies showed that chlorotoxin-conjugated QD-micelles can be specifically internalized into U-87 brain tumor cells. This work discloses that the scalable synthesis of AIS/ZnS QDs and the facile surface/interface chemistry for phase transfer and bioconjugation of these QDs may open an avenue for the produced QD-micelles to be applied to the detection of endogenous targets expressed on brain tumor cells, or more broadly to cell- or tissue-based diagnosis and therapy.”

 

PolySciTech mPEG-PLA used for enhancing resveratrol circulation time in blood-stream

PolySciTech (www.polyscitech.com) provides a wide array of block copolymers including mPEG-P(DL)La. Resveratrol is a naturally occurring chemical derived from plants that has been report to have many biological effects including chemoprevention and anti-oxidant activity. However, use of this medicine is difficult as this molecule does not last long inside the human body as it is metabolized to an inactive form rapidly (half-life < 8 minutes). Recently, researchers at Curtin University utilized mPEG-PLA from PolyScitech (PolyVivo AK084) as a starting molecule to graft a biodegradable PEG chain onto the resveratrol so as to improve its longevity in the blood stream. This molecule was tested in rodents and the half-life was observed to increase from < 8 minutes to 3 hours giving the resveratrol a longer time span over which it could express its pharmaceutical activity. Read more: Siddalingappa B, Benson HAE, Brown DH, Batty KT, Chen Y (2015) Stabilization of Resveratrol in Blood Circulation by Conjugation to mPEG and mPEG-PLA Polymers: Investigation of Conjugate Linker and Polymer Composition on Stability, Metabolism, Antioxidant Activity and Pharmacokinetic Profile. PLoS ONE 10(3): e0118824. doi:10.1371/journal.pone.0118824 http://dx.plos.org/10.1371/journal.pone.0118824

“Abstract:  Resveratrol is naturally occurring phytochemical with diverse biological activities such as chemoprevention, anti-inflammatory, anti-cancer, anti-oxidant. But undergoes rapid metabolism in the body (half life 0.13h). Hence Polymer conjugation utilizing different chemical linkers and polymer compositions was investigated for enhanced pharmacokinetic profile of resveratrol. Ester conjugates such as α-methoxy-ω-carboxylic acid poly(ethylene glycol) succinylamide resveratrol (MeO-PEGN-Succ-RSV) (2 and 20 kDa); MeO-PEG succinyl ester resveratrol (MeO-PEGO-Succ-RSV) (2 kDa); α-methoxy poly(ethylene glycol)-co-polylactide succinyl ester resveratrol (MeO-PEG-PLAO-Succ-RSV) (2 and 6.6kDa) were prepared by carbodiimide coupling reactions. Resveratrol-PEG ethers (2 and 5 kDa) were synthesized by alkali-mediated etherification. All polymer conjugates were fully characterized in vitro and the pharmacokinetic profile of selected conjugates was characterized in rats. Buffer and plasma stability of conjugates was dependent on polymer hydrophobicity, aggregation behavior and PEG corona, with MeO-PEG-PLAO-Succ-RSV (2 kDa) showing a 3h half-life in rat plasma in vitro. Polymer conjugates irrespective of linker chemistry protected resveratrol against metabolism in vitro. MeO-PEG-PLAO-Succ-RSV (2 kDa), Resveratrol-PEG ether (2 and 5 kDa) displayed improved pharmacokinetic profiles with significantly higher plasma area under curve (AUC), slower clearance and smaller volume of distribution, compared to resveratrol.”

Meet PolySciTech Booth 704 at the Controlled Release Society Expo

Representatives from PolySciTech Division of Akina, Inc. (www.polyscitech.com) will be at the 42cd annual Controlled Release Society Meeting & Exposition Edinburgh, Scotland July 26-29th. Meet with us at booth 704 to learn more about our products including Block copolymers (PEG-PLGA), Reactive intermediates (PLGA-PEG-Maleimide), Modified PEGS (Folate-PEG-COOH), Speciality monomers (Allyl Lactide), linear/speciality polyesters (PLA, PLGA-glucose), Polymer visualization (PLGA-fluorescein), Modified Chitosans (Chitosan-FITC), superporous hydrogels (aquagel), as well as others (poly(NIPAM) derivatives, thermogels). New this year we are highlighting our brand new product line 3DCellMaker. 3DCellMaker is a media modifier provided in convenient pre-sterilized aliquot kits for mixing with conventional cell-growth media (e.g. DMEM with FBS supplement) in order to generate a thermogelling cell media that allows cells to grow into 3-dimensional structures in conventional plastic/glass-ware containers (well plates, petri dishes) without the need for complex equipment. Learn more at (www.3dcellmaker.com).

 

PolyVivo PLGA-PEG-COOH used for nanoparticle based liver cancer therapy

PolySciTech (www.polyscitech.com) provides a wide array of polymer products including PolyVivo AI034 (PLGA-PEG-COOH). Recently this polymer was used to develop targeted nanoparticles that deliver salinomycin to cancer cells. Salinomycin typically acts as an antibiotic, but it has recently been discovered to also have cancer therapeutic effects in that it kills cancer stem cells even when the cancer is resistant to other therapies. High doses of salinomycin, however, can have toxic side effects necessitating a targeted delivery scheme so that a smaller, targeted dose can be administered (see http://www.hindawi.com/journals/bmri/2012/950658/ for an excellent review of salinomycin).  Nanoparticles cannot be controlled in the way that they move through the blood-stream but they can be chemically attached to specific proteins which preferentially adhere to cancer cell markers (named ‘aptamers’ or ‘ligands’). In this way, these nanoparticles can have their motion controlled by making them ‘stick’ to cancer cells. Recently, Jiang and coworkers utilized PLGA-PEG-COOH for conjugating cancer specific aptamers A15 and CL4, which target to the cancer markers CD133 and EGFR respectively, so as to generate a nanoparticle which preferentially adhere to liver cancer cells. These particles were then loaded with salinomycin and tested in a mouse tumor model. These were found to have good efficacy against liver cancer (hepatocellular carcinoma). Read more:  Jiang, Jianxin, Huaiwen Chen, Chao Yu, Yingying Zhang, Meiyuan Chen, She Tian, and Chengyi Sun. “The promotion of salinomycin delivery to hepatocellular carcinoma cells through EGFR and CD133 aptamers conjugation by PLGA nanoparticles.” Nanomedicine 10, no. 12 (2015): 1863-1879. http://www.futuremedicine.com/doi/abs/10.2217/nnm.15.43

“Abstract: Aims: To develop salinomycin-loaded poly(lactic-co-glycolic acid) nanoparticles conjugated with both CD133 aptamers A15 and EGFR aptamers CL4 (CESN), to target hepatocellular carcinoma (HCC) cells simultaneously expressing EGFR and CD133. Materials & methods: The antitumor activity and mechanism of CESN were investigated. Results & conclusion: The cytotoxicity of CESN in HCC cells and CD133+ HCC cells was superior to that of A15 or CL4-conjugted or nontargeted salinomycin-loaded nanoparticles. The antitumor assay in mice bearing HCC xenograft tumors confirmed the superior antitumor activity of CESN over other controls. We speculated that the improved therapeutic effect of CESN may be attributed to both targeting a higher percentage of HCC cells and increased delivery of salinomycin to HCC cells.”

PolySciTech (www.polyscitech.com) provides a wide variety of PLGA and related biodegradable polymers. One of the uses for this type of polymer is to generate biodegradable microparticles which contain medicine that slowly leaches out of the particles over the course of time (typically 1 to 6 months depending on formulation) so that this can be administered as long-acting injections. Recently a research article has been published in which the various parameters for generating protein loaded PLGA microparticles were optimized. This research has promise for the development of long-acting protein drug based injections which can be applied to many diseases. For example, proteins such as insulin is used to treat diabetes, infliximab is used to treat Crohns disease/arthritis, rituximab is used to treat lymphoma/leukemia and cetuximab is used to colorectal cancer. Use of PLGA-protein microparticles could one day provide for long-acting versions of these injected medicines. Read more: Martín-Sabroso, C., A. I. Fraguas-Sánchez, J. Aparicio-Blanco, M. F. Cano-Abad, and A. I. Torres-Suárez. “Critical attributes of formulation and of elaboration process of PLGA-protein microparticles.” International journal of pharmaceutics 480, no. 1 (2015): 27-36. http://www.sciencedirect.com/science/article/pii/S0378517315000101

“Abstract: Low drug loading, burst effect during release and drug inactivation account for the main drawbacks of protein microencapsulation in poly(d,l-lactic-co-glycolic) acid (PLGA) matrix by the water-in oil-in water (W/O/W) solvent evaporation method. Thus, the current study was set to invest the critical attributes of formulation and of elaboration process which determine protein loading into microparticles as well as its further release, using albumin as protein model. NaCl concentration in the external aqueous phase, poly(vinyl alcohol) (PVA) concentration and mostly viscosity of both the internal aqueous phase and the organic phase were critical attributes for improving drug loading, with polymer molecular weight and hydrophobicity likewise directly related to albumin loading. In such a way, when using 0.5% PVA as internal aqueous phase the highest albumin loading was achieved. Optimized microparticles exhibited a sustained in vitro release of albumin over 130 days. The influence of the microencapsulation process on albumin stability and biological activity was evaluated by carrying out cell proliferation assays on PC12 cells with albumin released from microparticles. Such assay demonstrated that the microencapsulation procedure optimized in this study did not affect the biological stability of the microencapsulated protein. Abbreviations: ALB, albumin; BCA, bicinchoninic acid; BSA, bovine serum albumin; DCM, dichloromethane; DMEM, Dulbecco’s modified Eagle’s medium; DMSO, dimethylsulfoxide; MP, microparticles; OD, optical density; PAO, phenylarsine oxide; PBS, phosphate buffered saline; PEG, poly(ethylene glycol); PLGA, poly(d,l-lactic-co-glycolic) acid; PVA, poly(vinyl alcohol); SEM, scanning electron microscopy; SPARC, secreted protein acidic and rich in cysteine; W/O/W, water-in oil-in water Keywords: Protein microencapsulation; Albumin; Microparticles; Quality by design; Critical attributes; Poly(lactic-co-glycolic) acid”