Nano structures through self-assembly of protected hydrophobic amino acids: encapsulation of rhodamine B dye by proline-based nanovesicles
The development of novel molecules for the creation of nanometer structures with specific properties has been the current interest of this research. We have developed a set of molecules from hydrophobic ω- and α-amino acids by protecting the –NH2 with Boc (t-butyloxycarbonyl) group and –CO2H with para-nitroanilide such as BocHN–Xx–CONH–(p–NO2)·C6H4, where Xx is γ-aminobutyric acid (γ-Abu), (l)-isoleucine, α-aminoisobutyric acid, proline, etc. These molecules generate various nanometer structures, such as nanofibrils, nanotubes and nanovesicles, in methanol/water through the self-assembly of bilayers in which the nitro benzene moieties are stacked in the middle and the Boc-protected amino acids parts are packed in the outer surface. The bilayers can be further stacked one over the other through hydrophobic interactions to form multilayer structure, which helps to generate different kinds of nanoscopic structures. The formation of the nanostructures has been facilitated through the participation of various noncovalent interactions, such as hydrophobic interactions, hydrogen bonding and aromatic π-stacking interactions. Fluorescence microscopy and UV studies reveal that the nanovesicles generated from pro-based molecule can encapsulate dye molecules which can be released by addition of acid (at pH 2). These single amino acid based molecules are both easy to synthesize and cost-effective and therefore offer novel scaffolds for the future design of nanoscale structures.
KeywordsDynamic Light Scattering Transmission Electron Microscopic Study Noncovalent Interaction Petroleum Ether Mixture Nanoscopic Structure
S. Kar would like to thank CSIR, New Delhi, India for a senior research fellowship (SRF). The financial assistance of UGC, New Delhi is acknowledged (Major Research Project, No.32-190/2006[SR]). We acknowledge the financial assistance of Centre for Research in Nanoscience & Nanotechnology (CRNN), University of Calcutta. We thank EPSRC and the University of Reading, UK for funds for Oxford Diffraction X-Calibur CCD diffractometer. We would like to thank Indian Institute of Chemical Biology, Kolkata, for helping us to perform the TEM experiments.
- 23.Lasic DD, Papahadjopoulos D (1996) Medical Applications of Liposomes. Elsevier Science, AmsterdamGoogle Scholar
- 31.Pierschbacher MD, Ruoslahti EJ (1987) Biol Chem 262:17294Google Scholar
- 42.Hunter CA, Lawson KR, Perkins J, Urch CJ (2001) J Chem Soc Perkin Trans 2:651Google Scholar
- 45.Förster S, Schmidt M (1995) Adv. Polym Sci 120:51Google Scholar
- 47.Förster S, Abetz V, Muller HE (2004) Advances in Polymer Science. Springer, BerlinGoogle Scholar
- 53.Bodanszky M, Bodanszky A (1984) The Practice of Peptide Synthesis. Springer, New YorkGoogle Scholar
- 54.Banerjee A, Balaram P (1997) Curr Sci 73:1067Google Scholar
- 63.Koley P, Pramanik A (2011) Adv Funct Mater. doi: 10.1002/adfm.201101465