Session: 16-01-01: Poster Session: NSF-Funded Research (Grad & Undergrad)

Paper Number: 100155

100155 - Tuning Energy Transport in Helical Protein Nanotubes Through Side-Chain Modifications 

Biopolymers are usually long-chain molecules comprised by repeating units, which widely exist in nature. Fibrous proteins have been widely used for various materials due to their biocompatibility, high flexibility and preeminent mechanical properties. With the development of bioelectronics technologies and cutting-edge flexible materials, biocompatible materials with higher or lower thermal conductivity are good at satisfying market demand. Hence, decoding the thermal transport mechanisms of proteins may guide a rational design for biomaterials with the desired functionality and tunable thermal properties. Here, employing non-equilibrium molecular dynamics, we investigate that side-chain mass plays an important role in thermal transport process through α-helix protein. α-helix with four representative residues, i.e. G, A, L and P residue, are illustrated to have different side-chain mass leading to distinct thermal conductivities. With each side-chain type, α-helix is highly shown to the size-dependent thermal conductivity increasing with the length. With the same size, α-helix is presented as thermal conductivity decreasing with increasing side-chain mass, demonstrating the negative contributions of side-chain mass to heat transfer. When phonon transport is fully diffusive, α-helix with G residue has the highest thermal conductivity among the four residue types, about 9.31 W m-1 K-1, which is 49.44% higher than that with A residue, 143.72% higher than that with L residue, and 250.00% higher than that with P residue. All these different thermal conductivities are caused by the residue having different mass and unique phonon properties associated with α-helix. Phonon dynamic analysis using spectral energy density, including dispersion relation, mode-based thermal conductivity, cumulative thermal conductivity, relaxation time, group velocity and vibration density of state, indicates that side-chain mass can obviously affect phonon properties of low-frequency acoustic and semi-optical phonons, and leads to the distinct thermal transport, which eventually leads to a reduced thermal conductivity. All these findings show that, α-helix can be engineered for producing functional biomaterials with tunable thermal performance by reasonable side-chain design, which are also supposed to improve the thermal transport mechanism of protein secondary structure and provide a theoretical perspective for designing efforts future to engineer advanced bio-inspired materials. Results suggest that heavy side-chain mass do not assist heat transport but substantially hinder heat transport. Phonon analysis further identifies side-chain mass as the major contributor to such fascinating phenomenon, which strikingly affect phonon properties of low-frequency acoustic and semi-optical phonons. These understandings may provide a fundamental insight into how to design and engineer protein-based biomaterial for desired thermal properties.

Presenting Author: Jiayue Hu Temple University

Presenting Author Biography: Jiayue Hu is a Ph.D. student in the Department of Mechanical Engineering at Temple University from Fall 2020. Before joining Temple, he received an MS degree in Aerospace Engineering from Auburn University and a BS degree in Engineering Mechanics from Beijing Institute of Technology, China. His current research interests include the multiscale modeling and simulation of advanced materials and molecular dynamics simulation about thermal transportation in proteins.

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