Mechanically rigid supramolecular assemblies formed from an Fmoc-guanine conjugated peptide nucleic acid

Bin Xue,David S Eisenberg,Leeor Kronik,Sofiya Kolusheva,Linda J W Shimon,Ido Azuri,Yiming Tang,Vasantha Basavalingappa,Yi Cao,Guanghong Wei,Ehud Gazit,Michael R Sawaya,Kai Tao,Santu Bera

doi:10.1038/s41467-019-13250-x

Abstract

The variety and complexity of DNA-based structures make them attractive candidates for nanotechnology, yet insufficient stability and mechanical rigidity, compared to polyamide-based molecules, limit their application. Here, we combine the advantages of polyamide materials and the structural patterns inspired by nucleic-acids to generate a mechanically rigid fluorenylmethyloxycarbonyl (Fmoc)-guanine peptide nucleic acid (PNA) conjugate with diverse morphology and photoluminescent properties. The assembly possesses a unique atomic structure, with each guanine head of one molecule hydrogen bonded to the Fmoc carbonyl tail of another molecule, generating a non-planar cyclic quartet arrangement. This structure exhibits an average stiffness of 69.6 ± 6.8 N m−1 and Young’s modulus of 17.8 ± 2.5 GPa, higher than any previously reported nucleic acid derived structure. This data suggests that the unique cation-free “basket” formed by the Fmoc-G-PNA conjugate can serve as an attractive component for the design of new materials based on PNA self-assembly for nanotechnology applications.

Highlights

The variety and complexity of deoxyribonucleic acid (DNA)-based structures make them attractive candidates for nanotechnology, yet insufficient stability and mechanical rigidity, compared to polyamidebased molecules, limit their application
Such Young’s modulus values are significantly lower compared to amino acids and polyamide-based materials, such as peptides, proteins, poly-paraphenylene terephthalamide (Kevlar®), poly(hexamethylene adipamide; Nylon 66®), and amyloidbased materials, where Young’s modulus can be as much as two orders of magnitude higher[19,20,21,22,23,24,25,26,27,28]. This suggests that assembly of a polyamide backbone in the structural pattern of DNA could pave the way for tailored design of novel synthetic materials offering high mechanical rigidity
The final products were purified through high-performance liquid chromatography (HPLC) and characterized by mass spectrometry (LC-MS, Fig. 1b, c and Supplementary Figs. 1–4) and nuclear magnetic resonance (NMR) spectroscopy (Supplementary Figs. 5–7)

Summary

Introduction

The variety and complexity of DNA-based structures make them attractive candidates for nanotechnology, yet insufficient stability and mechanical rigidity, compared to polyamidebased molecules, limit their application. The application of naturally derived DNA-based structures in material science is limited by their low stability and mechanical rigidity, with Young’s moduli of 0.3–2 GPa9–18 Such Young’s modulus values are significantly lower compared to amino acids and polyamide-based materials, such as peptides, proteins, poly-paraphenylene terephthalamide (Kevlar®), poly(hexamethylene adipamide; Nylon 66®), and amyloidbased materials, where Young’s modulus can be as much as two orders of magnitude higher[19,20,21,22,23,24,25,26,27,28]. We aimed to obtain mechanically rigid self-assembled nanostructures, inspired by nucleic acids For this purpose, we designed an Fmoc-G-PNA conjugated to a hydrophobic moiety, which increases the conformational space for folding by extending the chain length. The high mechanical rigidity and interesting photoluminescent features suggest that the self-assembled structures formed by the Fmoc-G-PNA tetramer may serve as components in the design of PNA-derived materials and as a starting point for future nanotechnology and optoelectronics applications

Objectives

Methods

Results

Conclusion