Concentration Dependent Transformation of Oligopeptide based Nanovesicles to Nanotubes and an Application of Nanovesicles

Abstract

The concentration dependent transformation of an oligopeptide nanostructure from nanovesicles to nanotubes at neutral pH is presented. The oligopeptide Acp-Tyr-Glu (Acp: 6-aminohexanoic acid) forms nanovesicles at a concentration of 6.9 mg mL(-1). At a concentration of 2.3 mg mL(-1) these vesicular structures completely disappear and nanotubular structures are observed. We have also successfully optimized an intermediate concentration (3.4 mg mL(-1)) where an ordered array of fused vesicular structures are formed, which actually leads to the transition from nanovesicles to nanotubes. These vesicular structures are very much sensitive toward metal ions and pH. Biocompatible calcium ions and high pH (10.7) can trigger the rupturing of these nanovesicles. One important property of these nanovesicular structures is the encapsulation of a potent anticancer drug doxorubicin, which can also be released in the presence of calcium ions promising a future use of these nanovesicles as vehicles for carrying biologically important molecules.

Nanostructures from Single Amino Acid‐Based Molecules: Stability, Fibrillation, Encapsulation, and Fabrication of Silver Nanoparticles

“…In order to examine the responsive behavior of nanovesicles of peptides I and VIII to be used as potential delivery vehicles, salt‐triggered disruption studies were carried out 6, 10b, 31. It is very interesting to know the disruption of these nanovesicles by interaction with biocompatible metal ions like K + and Ca +2 6, 31.…”

“…In order to examine the responsive behavior of nanovesicles of peptides I and VIII to be used as potential delivery vehicles, salt‐triggered disruption studies were carried out 6, 10b, 31. It is very interesting to know the disruption of these nanovesicles by interaction with biocompatible metal ions like K + and Ca +2 6, 31. Different microscopic analysis (SEM, TEM) revealed the complete rupture of the vesicular structures in the presence of various salts such as KCl and CaCl 2 (at a peptide/metal ion concentration ratio 1:1) at ambient temperature (Supporting Information, Figure S7a,c and S8a).…”

“…Different microscopic analysis (SEM, TEM) revealed the complete rupture of the vesicular structures in the presence of various salts such as KCl and CaCl 2 (at a peptide/metal ion concentration ratio 1:1) at ambient temperature (Supporting Information, Figure S7a,c and S8a). In order to examine whether this biocompatible K + and Ca +2 ions are selectively responsible for disruption or not, we also carried out this experiment with other salts such as N(n‐Bu) 4 Br and (NH 4 ) 2 SO 4 under the same experimental conditions, which make our studies different to previous studies 6, 31. SEM microscopy images clearly indicates the complete rupture of vesicular structures in the presence of (NH 4 ) 2 SO 4 and N(n‐Bu) 4 Br salts (Supporting Information, Figure S7b and S8b).…”

“…The design and fabrication of biomolecule‐based nanostructures are critically important as excellent vehicles for encapsulation and carrying various bioactive molecules into living systems due to their biocompatibility and exceptional adaptability for targeted delivery 1c,d, 6, 9b, 18, 31. Recently, there have been many reports on encapsulation properties of peptide‐ and pseudopeptide‐based nanostructures1d, 6, 18, 31, 40 but the entrapment behavior of various bioactive molecules into proteolytically stable very small single amino acid‐based nanovesicles has yet to be explored. Here we have examined an in vitro model to show the efficiency of these reported nanovesicles as a delivery vehicle for a potent household hydrophobic fluorescent drug, curcumin, as well as the encapsulation behavior of various guest molecules, such as fluorescent dyes rhodamine B, acridine orange, and a synthetic isoindolefused imidazole‐based fluorescent molecule 41.…”

“…Self‐assembling peptide‐based scaffolds are very interesting candidates for constructing well‐defined nanostructures and advanced materials owing to their biocompatibility, capability of specific molecular recognition, easy availability, and functional flexibility 1. Several highly versatile peptide‐based structural and functional building blocks – such as cyclic peptides,2 dendritic peptides,3 amphiphile peptides,4 surfactant‐like peptides,1h, 5 oligopeptides,6 copolypeptides,7 aromatic conjugated dipeptides,8 and aromatic dipeptides1e,j,k, 9 – are found to spontaneously associate to form various morphologies, like nanotubes, nanospheres, nanofibrils, nanorods, nanotapes, and organogels, under different conditions 1–9. Presently, the key challenge in the field is to control the morphology of self‐assembling peptide nanostructures using processing parameters.…”