Recently, the Li Zhou Group of the Beijing Institute of Nano Energy and Systems, Chinese Academy of Sciences and the Li Zigang Task Force of the Shenzhen Graduate School of Peking University and Wang Xinwei's Research Group have applied the new model of α-helix polypeptide self-assembly and its application in energy storage. New progress has been made in China, and relevant research results have been published in the recent Science Advances of Science (DOI: 10.1126/sciadv.aar5907).
Accurate hierarchical self-assembly of polypeptide molecules as a method of bottom-up preparation of bio-nano-micro materials, which has been subjected to biomimetics, catalysis, material separation, and bioelectronic devices. More and more attention has been paid to it. Compared with inorganic nanomaterials, polypeptide molecules have a wide range of sources, are naturally degradable, have good biocompatibility, and are easy to modify. They are based on FF (F: phenylalanine) dipeptides and their derivatives. Representative, through a series of physics (electric field assisted method, magnetic field assisted method, temperature-assisted method, ultrasound-assisted method) and chemistry (pH, solvent method, catalytic method) means to accurately manipulate the pathway of polypeptide molecule self-assembly, resulting in polypeptide nanotubes Nanofibers, Nanowires, Nanogels, Nano Quantum Dots, etc. A series of nano-polypeptide materials with special structures, these materials either possess good semiconductor properties, or exhibit superior flexibility and special optical properties. Supercapacitors/batteries, piezoelectric devices, biosensors, photoconductive devices, and biomedical applications are widely used.
Self-assembly of polypeptide molecules is a way to achieve long-range ordering of polypeptide molecules under certain conditions by adjusting non-covalent interactions between polypeptide molecules, such as van der Waals forces, hydrogen bonding networks, hydrophobic interactions, and π-π interactions. Means. As the molecular structure of polypeptides is complex and diverse, changes in the polypeptide sequence lead to different molecular properties. Therefore, it is very difficult to predict and design the self-assembly of polypeptide molecules. The research on polypeptide self-assembly in early years mainly focused on amphipathic polypeptide molecules, β- Folded peptides, end-to-end circular DLD polypeptide molecules, and FF dipeptide molecules. For the more complex self-assembly of helical polypeptides, little is reported. The reason is that the entropy of spiral polypeptides is low and the hydrogen bond network is blocked inside the polypeptide. It is difficult to form hydrogen-bonding networks between molecules. Therefore, how to manipulate polypeptides with more complex secondary structures, such as helical peptides, to achieve controlled self-assembly is one of the most difficult points in current research.
Li Zhou's research group has long paid attention to and published a series of preparations and applications of implantable devices based on biodegradable molecules. Given the great promise of polypeptide molecules in this field, the research group conducts energy storage and sensing of peptide nanomaterials. The research has published relevant papers in the international academic journal Small. Recently, Li Zhou and his collaborators have developed a new method for preparing peptide nanomaterials based on a chirality-inducing helix. Based on this system, researchers believe that: Through the driving force-side loop interaction outside the main chain, to overcome the shortcomings of the lack of driving force for the self-assembly of the helical polypeptide backbone, a novel mode of peptide assembly method is realized, namely the so-called 'side loop driven' peptide self-assembly. Based on such an idea, the researchers conducted detailed screening and characterization. They used pentapeptides as a model and designed and synthesized a series of pentapeptide molecules with chiral side rings named BDCP. The results showed that when BDCP is a helix When the structure of the side ring substituents is aromatic, the polypeptide molecules can be assembled into nanotube/nanoribbon structures.
Next, they studied the mechanism of polypeptide self-assembly. Through the cooperation with two research groups of the Graduate School of Shenzhen University, Peking University, the crystal structure of the peptide assembly structure was predicted, and an assembly model of polypeptide molecules was obtained. The model showed that Good agreement with the experimental results. The results show that π-π interactions between polypeptide molecules, S-π interactions, and hydrogen bonding networks drive the assembly of polypeptide molecules. In polypeptide assembly, polarity and non-polarity The interface is formed in turn, and the dipoles in each of the two polar layers are in the opposite direction, so that the dipole interactions inside the assembly cancel each other out, further stabilizing the assembly. This is the first time that S-π interactions have been reported in this field. Examples of peptide self-assembly.
On this basis, the researchers further studied the optical and electrical properties of the assembled materials. Under different excitation light irradiation, the polypeptide assembly can emit from blue to red fluorescence. This material has a huge application prospect in the field of biological imaging. In the electrical test, under the guidance of Li Zhou, the researchers investigated the energy storage properties of peptide assemblies as supercapacitor active materials. In 2009, scientists from Israel reported for the first time a cyclic phenylalanine dipeptide 'nano forest' material. Applications in energy storage. The study shows that peptide materials have good mechanical and electrical properties, combined with the high specific surface area of peptide nanomaterials, appropriate hydrophilicity and hydrophobicity, and excellent conductive properties, etc. A potential alternative to flexible, implantable, lightweight, non-polluting energy storage devices. In this study, the researchers systematically compared the electrochemical properties of four groups of polypeptide molecules. The results indicate that the energy storage of polypeptide materials can be achieved through peptide sequences. Regulation. Cyclic voltammetry, galvanostatic charge-discharge and other electrochemical measurement methods are used to prove that the peptide material has a good circulation. Qualitative and capacitive properties of the magnification ratio is higher than FF polypeptide material.
This research not only has important theoretical value in the preparation of polypeptide materials, but also has important application prospects. Hu Kuan, assistant researcher of Li Zhou Group, is the co-first author of the dissertation, Ph.D. student Li Hu made in electrochemical tests. Contributions. Based on the above work, Li Zhou's research group is currently actively carrying out research on polypeptide energy storage and polypeptide piezoelectricity.
SEM photographs of the structure and assembly of polypeptide molecules
Molecular Structure Prediction of Peptide Assemblies
Electrochemical properties of polypeptide assemblies
