Integrative Graduate
Education and
Research Traineeship

Highlight

Peptide-Templated Interfacial Biominerization

Peptide based nucleation of abiotic crystals at the air-water interface.

Projects:

Multiscale Phenomena in Soft Materials

Institution:

City University of New York City College

Primary Strategic Goal:

Discovery: Foster research that will advance the frontiers of knowledge, emphasizing areas of greatest opportunity and potential benefit and establishing the Nation as a global leader in fundamental transformational science and engineering.

Secondary Strategic Goal:

Learning: Build the Nation's research capability through critical investments in advanced instrumentation, facilities, cyber infrastructure, and experimental tools.

Achievement/Results

Nature has the ability to construct exquisite organic-inorganic composite materials with structures that cover a vast range of length scales (Å to mm) and capture the benefits of each constituent’s properties. Professor Raymond Tu and his group at The City College of New York have designed and synthesized a set of peptide-based self-assembly that can be used to explore the inherent complexity associated with bio-mineralization. The NSF Integrative Graduate Education and Research Traineeship (IGERT) is funding PhD student Lorraine Leon, who is applying these molecular designs to study the role of shape anisotropy and charge distribution in templated biomineralization processes. The impacts of understanding this phenomenon can then be translated into novel materials with composite properties.

One example of a peptide that has been designed for this project is a b-strand, composed of alternating hydrophobic-hydrophilic amino acids to define a surface-active secondary structure (see figure). The design incorporates:

1. Alternating periodicity, where hydrophobic and hydrophilic residues are presented on either face of the b-strand.
2. Precise spatial control over the charge separation.
3. Cysteine residues for cross-linking.
4. Optically active residues (tryptophan) for quantification and imaging.

The supramolecular behavior of this peptide is investigated at the air/water interface using Langmuir-Blodgett techniques coupled with Circular Dichroism spectropolarimetry and Brewster angle microscopy. Langmuir-blodgett isotherms have shown a large degree of hysteresis, which is characteristic of the interfacial crystallization of the peptide. Additionally, the behavior of the peptide monolayers is being investigated as a function of electrolyte concentration in the sub-phase in order to obtain information on the influence of charge on the self-assembled structure. The self-organization of this peptide at the air/water interface is characterized at two length-scales: (1) nanometer-length scale with circular dichroism to investigate the secondary structure and (2) micron-length scale with Brewster angle microscopy to visualize aggregate length scale (see figure). The analysis of this behavior should provide insight into how the peptide will control the nucleation of inorganic crystals.

Address Goals

Primary: Discovery – This project seeks to better understand the structural consequences of kinetics on a ubiquitous natural phenomenon, biomineralization. These ideas can then be translated into technology to synthesize novel materials.

Secondary: Research Infrastructure – This project applies peptides as a template that can be used generically to examine a variety to physical phenomena where nanoscale order is the basis for behavior. These peptides can be viewed as a general platform for any experiments that require manipulation of chemical functionality at short length scales