Colloids and Surfaces B: Biointerfaces 95 (2012) 154–161 Contents lists available at SciVerse ScienceDirect Colloids and Surfaces B: Biointerfaces j our na l ho me p age: www.elsevier.com/locate/colsurfb Fabrication of ellagic acid incorporated self-assembled peptide microtubes and their applications Stacey N. Barnaby a , Karl R. Fath b,c , Areti Tsiola b,1 , Ipsita A. Banerjee a,∗ a Department of Chemistry, Fordham University, 441 East Fordham Road, Bronx, NY 10458, United States b Biology Department, Queens College, The City University of New York, 6530 Kissena Boulevard, Flushing, NY 11367, United States c The Graduate Center, The City University of New York, 365 Fifth Avenue, New York, NY 10016, United States a r t i c l e i n f o Article history: Received 1 December 2011 Received in revised form 20 February 2012 Accepted 21 February 2012 Available online 1 March 2012 Keywords: Peptides Bolaamphiphiles Self-assembly Ellagic acid Threonine a b s t r a c t Ellagic acid (EA), a plant polyphenol known for its wide-range of health benefits was encapsulated within self-assembled threonine based peptide microtubes. The microtubes were assembled using the synthe- sized precursor bolaamphiphile bis(N--amido threonine)-1,5-pentane dicarboxylate. The self-assembly of the microstructures was probed at varying pH. In general, tubular formations were observed at a pH range of 4–6. The formed microtubes were then utilized for fabrication with EA. We probed the ability of the microtubes as drug release vehicles for EA as well as for antibacterial applications. It was found that the release of EA was both pH and concentration dependent. The biocompatibility as well as cytotoxicity of the EA-fabricated microtubes was examined in the presence of mammalian normal rat kidney (NRK) cells. Finally the antibacterial effects of the EA incorporated peptide microtubes was examined against Escherichia coli and Staphylococcus aureus. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Over the past decade, there has been a tremendous surge in the development of nanomaterials to mimic and target biological systems for various biomedical as well as biosensor applica- tions [1–3]. Specifically, a plethora of nanomaterials have been explored for their potential in drug delivery applications. For example, Yang et al. [4] designed polymer vesicles from hetero- functional amphiphilic triblock copolymers for targeted anticancer drug delivery. In a separate study, lipid–polymer hybrid nanopar- ticles were designed for targeting of mammalian cells or tissues [5]. Polymer nanoparticles consisting of PFO (polyfluorene) and poly(l-glutamic acid) conjugated with doxorubicin have also been fabricated [6]. Amphiphilic block copolymer micelles have been uti- lized as hydrophobic drugs within films [7]. Polymeric dendrimers have also been fabricated using poly(l-glutamic acid) [8], and its subsequent conjugation with DOX allowed for a targeted drug delivery system. Gao et al. [9] have designed nanoparticles based on polyacrylamide that could avoid being up taken by macrophages. Furthermore, Ding et al. [10] designed a system of cisplatin ∗ Corresponding author. Tel.: +1 718 817 4445; fax: +1 718 817 4432. E-mail address: banerjee@fordham.edu (I.A. Banerjee). 1 Current address: Department of Biological Sciences and Geology, Queensboro Community College, 222-05 56th Avenue, Bayside, NY 11364, United States. (CDDP)-loaded gelatin/poly(acrylic acid) nanoparticles for trans- tissue drug delivery. In addition to various synthetic structures, natural drug delivery systems have also been investigated, such as chitosan [11–13], pullulan [14–17], alginates [18–23], and hyaluronic acid [24–26]. For example, chitosan-functionalized graphene oxide hybrid nanosheets were fabricated for the controlled release of Ibubrofen and 5-fluorouracil [27]. The biopolymer pullulan has been modified and its ability to self-assemble into hydrogels for drug delivery has been explored. Pullulan hydrogels have been found to serve as a coating for stents needed in local arterial ther- apy. Furthermore, pullulan/DOX conjugated nanoparticles were utilized as drug delivery vehicles for pH-controlled release. Several hyaluronic acid (HA) conjugates have also been synthesized and allowed to self-assemble into nanoparticles that were shown to tar- get tumors [26]. Alginate based copolymers composed of 1–4 linked -l-guluronic acid and -d-mannuronic acid have been functional- ized with proteins and utilized for the controlled release of TGF- 1, basic fibroblast growth factor (bFGF), tumor necrosis factor recep- tor (TNFR), as well as angiogenesis factor, epidermal growth factor (EGF), and urogastrone. In a separate study, DOX was released from alginate embedded magnetic nanoheaters. Peptide nanotubes and microtubes are a relatively new class of biomaterials that have garnered much interest because of their facile self-assembly and ability to be functionalized, as well as their biocompatibility [28–33]. Nanotubes grown from cationic 0927-7765/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.colsurfb.2012.02.031