Nanoencapsulating living biological cells using electrostatic layer-by-layer self-assembly: Platelets as a model
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Bingyun Lia) Department of Orthopaedics, School of Medicine, West Virginia University, Morgantown, West Virginia 26506; WVNano Initiative, Morgantown, West Virginia 26506; and Department of Chemical Engineering, College of Engineering and Mineral Resources, West Virginia University, Morgantown, West Virginia 26506 (Received 5 May 2010; accepted 16 July 2010)
In the literature, a few biological cells have been used as templates to form microcapsules of a variety of shapes and sizes. In this study, we proved the concept that living cells like platelets can be encapsulated with polyelectrolytes using electrostatic layer-by-layer self-assembly (LBL), and, most importantly, the encapsulation process did not induce activation of the platelets. Glycolchitosan and poly-L-glutamic acid were electrostatically deposited onto platelets, and the encapsulation was confirmed using confocal laser scanning microscopy and scanning electron microscopy. Transmission electron microscopy observation further confirmed that the encapsulation process was mild and the activation of platelets was negligible. The encapsulation of living biological cells like platelets can serve as a model system in a wide range of biomedical applications including local and sustained drug delivery, immune protection of artificial tissues, and versatile artificial blood.
I. INTRODUCTION
Encapsulation of living biological cells has broad potential applications to treat major human diseases, including encapsulating allogeneic islets to treat diabetes, encapsulating bovine adrenal chromaffin cells to treat chronic pain, and encapsulating genetically engineered cells that produce clotting factor IX to treat hemophilia.1 In the latter, sustained delivery of factor IX via cell encapsulation would circumvent the hemorrhagic crises associated with the disease thus providing a much improved and more economic therapy. The potential economic impacts of cell encapsulation as therapeutics are enormous because nearly one-half trillion dollars are spent every year in the United States alone to care for patients suffering from tissue loss or dysfunction. One promising technique for cell encapsulation is called electrostatic layer-by-layer self-assembly (LBL), which is based on the attachment of oppositely charged polyions onto charged surfaces in a self-assembly process.2 A variety of polyelectrolytes have been used to modify surfaces of implants or cells. Our laboratory demonstrated that LBL could be used to prepare antibacterial implant surfaces that provide controlled local release of cytokines3,4 and antibiotics.5–7 Work by others showed that LBL surface modification could lead to targeting of cancer cells8 and prolonged in vivo circulation time.9 a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2010.23 J. Mater. Res., Vol. 26, No. 2, Jan 28, 2011
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Moreover, living Saccharomyces cerevisiae yeast was encapsulated with polyelectrolyte multilayers using LBL technology, and the encapsu
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