Tuesday, October 18, 2016

PLGA from PolySciTech used as part of antimicrobial bioadhesive development

PolySciTech division of Akina, Inc. (www.polyscitech.com) provides a wide array of biodegradable polymers including PLGA. Recently, researchers working on development of novel bioadhesives used PLGA from PolySciTech (Cat# AP154) as a control for standardizing their cytotoxicity assay. This research holds promise for development of novel wound-closure technologies such as bioadhesives which can be used to ‘glue’ wounds shut, in a biocompatible matter, so as to reduce the need for staples and sutures. Read more: Guo, Jinshan, Gloria B. Kim, Dingying Shan, Jimin P. Kim, Jianqing Hu, Wei Wang, Fawzi G. Hamad, Guoying Qian, Elias B. Rizk, and Jian Yang. "Click chemistry improved wet adhesion strength of mussel-inspired citrate-based antimicrobial bioadhesives." Biomaterials (2016). http://www.sciencedirect.com/science/article/pii/S014296121630552X

“Abstract: For the first time, a convenient copper-catalyzed azide-alkyne cycloaddition (CuAAC, click chemistry) was successfully introduced into injectable citrate-based mussel-inspired bioadhesives (iCMBAs, iCs) to improve both cohesive and wet adhesive strengths and elongate the degradation time, providing numerous advantages in surgical applications. The major challenge to developing such an adhesive was the mutual inhibition effect between the oxidant used for crosslinking catechol groups and the Cu(II) reductant used for CuAAC, which was successfully minimized by adding a biocompatible buffering agent typically used in cell culture, 4-(2-hydroxyethyl) -1-piperazineethanesulfonic acid (HEPES), as a copper chelating agent. Among the investigated formulations, the highest adhesion strength achieved (223.11 ± 15.94 kPa) was around 13 times higher than that of a commercially available fibrin glue (15.4 ± 2.8 kPa). In addition, dual-crosslinked (i.e. click crosslinking and mussel-inspired crosslinking) iCMBAs still preserved considerable antibacterial and antifungal capabilities that are beneficial for the bioadhesives used as hemostatic adhesives or sealants for wound management. Keywords: Click chemistry; Bioadhesives; Mussel; Citric acid; Antimicrobial”

PLGA from PolySciTech used as part of development of Mg-Zn-Sr implantable alloy

PolySciTech Division of Akina, Inc. (www.polyscitech.com) provides a wide array of biodegradable polymers including PLGA. Because of the great deal of characterization provided with our materials and the long, clinical history of PLGA, often these polymers are used as controls to evaluate novel surfaces against. Recently, researchers generated a novel implant alloy and evaluated it’s cytocompatibility against PLGA from PolySciTech (Cat# AP049) using HUVEC cell culture. This allowed for comparison of their novel surface against known materials as a control so as to standardize the results. This research holds promise for the development of novel implant metals such as degradable cardiac stents or other implants. Read more: Cipriano, Aaron F., Amy Sallee, Myla Tayoba, Mayra C. Cortez, Alan Lin, Ren-Guo Guan, Zhan-Yong Zhao, and Huinan Liu. "Cytocompatibility and Early Inflammatory Response of Human Endothelial Cells in Direct Culture with Mg-Zn-Sr Alloys." Acta Biomaterialia (2016). http://www.sciencedirect.com/science/article/pii/S1742706116305475

“Abstract: Crystalline Mg-Zinc (Zn)-Strontium (Sr) ternary alloys consist of elements naturally present in the human body and provide attractive mechanical and biodegradable properties for a variety of biomedical applications. The first objective of this study was to investigate the degradation and cytocompatibility of four Mg-4Zn-xSr alloys (x = 0.15, 0.5, 1.0, 1.5 wt.%; designated as ZSr41A, B, C, and D respectively) in the direct culture with human umbilical vein endothelial cells (HUVEC) in vitro. The second objective was to investigate, for the first time, the early-stage inflammatory response in cultured HUVECs as indicated by the induction of vascular cellular adhesion molecule-1 (VCAM-1). The results showed that the 24-hr in vitro degradation of the ZSr41 alloys containing a β-phase with a Zn/Sr at.% ratio 1.5 was significantly faster than the ZSr41 alloys with Zn/Sr at.% 1. Additionally, the adhesion density of HUVECs in the direct culture but not in direct contact with the ZSr41 alloys for up to 24 hrs was not adversely affected by the degradation of the alloys. Importantly, neither culture media supplemented with up to 27.6 mM Mg2+ ions nor media intentionally adjusted up to alkaline pH 9 induced any detectable adverse effects on HUVEC responses. In contrast, the significantly higher, yet non-cytotoxic, Zn2+ ion concentration from the degradation of ZSr41D alloy was likely the cause for the initially higher VCAM-1 expression on cultured HUVECs. Lastly, analysis of the HUVEC-ZSr41 interface showed near-complete absence of cell adhesion directly on the sample surface, most likely caused by either a high local alkalinity, change in surface topography, and/or surface composition. The direct culture method used in this study was proposed as a valuable tool for studying the design aspects of Zn-containing Mg-based biomaterials in vitro, in order to engineer solutions to address current shortcomings of Mg alloys for vascular device applications. Statement of significance: Magnesium (Mg) alloys specifically designed for biodegradable implant applications have been the focus of biomedical research since the early 2000s. Physicochemical properties of Mg alloys make these metallic biomaterials excellent candidates for temporary biodegradable implants in orthopedic and cardiovascular applications. As Mg alloys continue to be investigated for biomedical applications, it is necessary to understand whether Mg-based materials or the alloying elements have the intrinsic ability to direct an immune response to improve implant integration while avoiding cell-biomaterial interactions leading to chronic inflammation and/or foreign body reactions. The present study utilized the direct culture method to investigate for the first time the in vitro transient inflammatory activation of endothelial cells induced by the degradation products of Zn-containing Mg alloys. Keywords: Biodegradable Magnesium Zinc Strontium alloy; Mg-Zn-Sr alloy; Human umbilical vein endothelial cells (HUVEC); Induction of vascular cell adhesion molecule-1 (VCAM-1); Early inflammatory response; Biomedical implants”

Wednesday, October 12, 2016

Jenny’s Rescue

Get back to polymer basics in the informational narrative between Jenny and Steve and a humorous yet educational lesson as to why you should never fall asleep in polymer chemistry class at www.everypolymer.com

Tuesday, October 11, 2016

Resorbable vascular graft development using PLCL, PLA, and PGA investigated for heart repair

PolySciTech division of Akina, Inc. (www.polyscitech.com) provides a wide array of biodegradable polymers including PLCL, PLA, and PGA. Recently, researchers have utilized these types of polymers to generate arterial vascular grafts that allow for good cellular growth for use in tissue engineering. This research holds promise for repairing damaged or missing heart tissue. Read more: Sugiura, Tadahisa, Shuhei Tara, Hidetaka Nakayama, Tai Yi, Yong-Ung Lee, Toshihiro Shoji, Christopher K. Breuer, and Toshiharu Shinoka. "Fast-degrading bioresorbable arterial vascular graft with high cellular infiltration inhibits calcification of the graft." Journal of Vascular Surgery (2016). http://www.sciencedirect.com/science/article/pii/S0741521416308230

“Abstract: Objective: Bioresorbable vascular grafts are biologically active grafts that are entirely reconstituted by host-derived cells through an inflammation-mediated degradation process. Calcification is a detrimental condition that can severely affect graft performance. Therefore, prevention of calcification is of great importance to the success of bioresorbable arterial vascular grafts. The objective of this study was to test whether fast-degrading (FD) bioresorbable arterial grafts with high cellular infiltration will inhibit calcification of grafts. Methods: We created two versions of bioresorbable arterial vascular grafts, slow-degrading (SD) grafts and FD grafts. Both grafts had the same inner layer composed of a 50:50 poly(l-lactic-co-ε-caprolactone) copolymer scaffold. However, the outer layer of SD grafts was composed of poly(l-lactic acid) nanofiber, whereas the outer layer of FD grafts was composed of a combination of poly(l-lactic acid) and polyglycolic acid nanofiber. Both grafts were implanted in 8- to 10-week-old female mice (n = 15 in the SD group, n = 10 in the FD group) as infrarenal aortic interposition conduits. Animals were observed for 8 weeks. Results: von Kossa staining showed calcification in 7 of 12 grafts in the SD group but zero in the FD group (P < .01, χ2 test). The cell number in the outer layer of FD grafts was significantly higher than in the SD grafts (SD, 0.87 ± 0.65 × 103/mm2; FD, 2.65 ± 1.91 × 103/mm2; P = .02). Conclusions: The FD bioresorbable arterial vascular graft with high cellular infiltration into the scaffold inhibited calcification of grafts.”

Learn more about micro and nanotechnology at Small World

A technical information site unlike any you have seen before is now available. See the informational narrative between Nicole Klein and Mike Rometer as they explore the world of micro and nanoparticles together at Small-World.

Friday, October 7, 2016

mPEG-PCL investigated for treatment of fungal diseases

PolySciTech Division of Akina, Inc. (www.polyscitech.com) provides a wide array of biodegradable polymers including PEG-PCL. Typically diblock mPEG-PCL is utilized primarily to form drug micelles for drug delivery. However, recently, researchers have found that mPEG-PCL selectively initiates native Staphylococcus lugdunensis to undergo fermentation, which produces acetic and isovaleric acids that act to suppress the growth of fungal Candida parapsilosis. This research holds promise for providing treatment to a wide array of fungal skin diseases. Read more: Kao, M. S., Y. Wang, S. Marito, S. Huang, and W. Z. Lin. "The mPEG-PCL Copolymer for Selective Fermentation of Staphylococcus lugdunensis Against Candida parapsilosis in the Human Microbiome." J Microb Biochem Technol 8 (2016): 259-265. http://www.omicsonline.org/open-access/the-mpegpcl-copolymer-for-selective-fermentation-of-staphylococcus-lugdunensis-against-candida-parapsilosis-in-the-human-microbiom-1948-5948-1000295.pdf

“Abstract: Many human skin diseases, such as seborrheic dermatitis, potentially occur due to the over-growth of fungi. It remains a challenge to develop fungicides with a lower risk of generating resistant fungi and non-specifically killing commensal microbes. Our probiotic approaches using a selective fermentation initiator of skin commensal bacteria, fermentation metabolites or their derivatives provide novel therapeutics to rein in the over-growth of fungi. Staphylococcus lugdunensis (S. lugdunensis) bacteria and Candida parapsilosis (C. parapsilosis) fungi coexist in the scalp microbiome. S. lugdunensis interfered with the growth of C. parapsilosis via fermentation. A methoxy poly(ethylene glycol)-b-poly(ɛ-caprolactone) (mPEG-PCL) copolymer functioned as a selective fermentation initiator of S. lugdunensis, selectively triggering the S. lugdunensis fermentation to produce acetic and isovaleric acids. The acetic acid and its pro-drug diethyleneglycol diacetate (Ac-DEG-Ac) effectively suppressed the growth of C. parapsilosis in vitro and impeded the fungal expansion in the human dandruff. We demonstrate for the first time that S. lugdunensis is a skin probiotic bacterium that can exploit mPEG-PCL to yield fungicidal short-chain fatty acids (SCFAs). The concept of bacterial fermentation as a part of skin immunity to re-balance the dysbiotic microbiome warrants a novel avenue for studying the probiotic function of the skin microbiome in promoting health.” 

Monday, October 3, 2016

Anti-HIV/AIDS vaginal prophylactic nanoparticle delivery system development research done using PolySciTech’s PLGA-Fluorescein

PolySciTech division of Akina, Inc. (www.polyscitech.com) provides a wide array of biodegradable polymers. One type of polymer is fluorescein-conjugated PLGA Mn: 20-40K (E.G. PolyVivo AV004) which is a useful polymer for tracking biodegradable systems such as nanoparticles by fluorescence techniques. Recently, researchers in Portugal used this polymer to generate traceable nanoparticles containing anti-retroviral drugs (efavirenz and tenofovir) for incorporation into a thin film as part of vaginal prophylactic against HIV-AIDS. They traced genital distribution as well as delivery and pharmacokinetics of the antiretroviral agents in a mouse model. This research holds promise to provide for a new tool in limiting the transmission of this deadly disease. Read more: Cunha-Reis, Cassilda, Alexandra Machado, Luísa Barreiros, Francisca Araújo, Rute Nunes, Vítor Seabra, Domingos Ferreira, Marcela A. Segundo, Bruno Sarmento, and José das Neves. "Nanoparticles-in-film for the combined vaginal delivery of anti-HIV microbicide drugs." Journal of Controlled Release (2016). http://www.sciencedirect.com/science/article/pii/S0168365916307891

“Abstract: Combining two or more antiretroviral drugs in one medical product is an interesting but challenging strategy for developing topical anti-HIV microbicides. We developed a new vaginal delivery system comprising the incorporation of nanoparticles (NPs) into a polymeric film base – NPs-in-film – and tested its ability to deliver tenofovir (TFV) and efavirenz (EFV). EFV-loaded poly(lactic-co-glycolic acid) NPs were incorporated alongside free TFV into fast dissolving films during film manufacturing. The delivery system was characterized for physicochemical properties, as well as genital distribution, local and systemic 24 h pharmacokinetics (PK), and safety upon intravaginal administration to mice. NPs-in-film presented suitable technological, mechanical and cytotoxicity features for vaginal use. Retention of NPs in vivo was enhanced both in vaginal lavages and tissue when associated to film. PK data evidenced that vaginal drug levels rapidly decreased after administration but NPs-in-film were still able to enhance drug concentrations of EFV. Obtained values for area-under-the-curve for EFV were around one log10 higher than those for the free drugs in aqueous vehicle. Film alone also contributed to higher and more prolonged local drug levels as compared to the administration of TFV and EFV in aqueous vehicle. Systemic exposure to both drugs was low. NPs-in-film was found to be safe upon once daily vaginal administration to mice, with no significant genital histological changes or major alterations in cytokine/chemokine profiles being observed. Overall, the proposed NPs-in-film system seems to be an interesting delivery platform for developing combination vaginal anti-HIV microbicides. Chemical compounds studied in this article Efavirenz (PubChem CID: 64139); Hypromellose (PubChem CID: 57503849); Tenofovir (PubChem CID: 464205) Keywords HIV/AIDS; Nanotechnology; Pharmacokinetics; Pre-exposure prophylaxis; Safety; Vaginal drug administration”