Question

what kind of concentration effects can be seen in the self assembly of amino acids?

Answer 1

Self-assembling amino acids are a new class of biomaterials, which have many potential applications in biomedical and pharmaceutical areas, the self-assembling amino acids are biocompatible and biodegradable.These properties make them ideal as matrices in tissue engineering and carriers in drug delivery systems. Playing an active role in cell adhesion, cell morphologies, and cell functions, matrices made of self-assembling amino acids have been reported to support mammalian cell attachment in different manners. Self-assembling amino acids have been used as a scaffold for neurite outgrowth and synapse formation, and do not induce any measurable immune response or tissue inflammation when introduced into animals.

Concentration effect on self assembly of amino acids:

Many researches have been conducted to study the effect of concentration, one such research studying the concentration effect on the aggregation of self assembling oligopeptide ( a peptide molecule with a small number of amino acids) states that:

The concentration dependence of self-assembling oligopeptides is expected to be similar to that of biosurfactants, which have both hydrophobic and hydrophilic parts. By analogy with surfactants, a concentration study may allow one to determine the critical aggregation concentration (CAC). Similar to micellar systems, it is expected that the oligopeptides are in the monomer form below the CAC, while peptide aggregation starts to occur at and above the CAC. Time is also involved in the aggregation process. It provides information on the timescale over which the aggregation takes place. This is important to understand the kinetics of aggregation.

By investigating the concentration effects, an aggregation mechanism of EAK16-II(peptide molecule with three amino acids Ala, Glu and Lys) is proposed. Depending on the critical aggregation concentration (CAC) of EAK16-II, the oligopeptide aggregates into protofibrils through seeding and/or a nucleation process. Protofibrils then associate with each other to form fibrils. The CAC was found to be ∼0.1 mg/ml by surface tension measurements. The nanostructures of aggregates were imaged and analyzed by atomic force microscopy. Globular and fibrillar aggregates were observed, and their dimensions were further quantified. To ensure that the aggregates were formed in bulk solution, light scattering (LS) measurements were conducted to monitor the fibril formation with time. The LS profile showed two different rates of aggregation depending on whether the peptide concentration was above or below the CAC. At high concentrations, the LS intensity increased strongly at early times. At low concentrations, the LS intensity increased only slightly. This study provides information about the nature of the oligopeptide self-assembly, which is important to the understanding of the fibrillogenesis occurring in conformational diseases and to many biomedical engineering applications.