Nanoflowers with a difference
Image: SEM images of DNA-nanoflowers
Korea-based KAIST researchers have revealed an eco-friendly method to synthesise DNA-copper nanoflowers with high load efficiencies, low cytotoxicity, and strong resistance against nucleases.
Developed by Professor Hyun Gyu Park from the Department of Chemical and Biomolecular Engineering and colleagues, the method forms flower-shaped nanostructures by using interactions between copper ions and DNA containing amide and amine groups.
SEM images highlight nanoflowers that exhibit high DNA loading capacities in addition to low cytotoxicity.
Nanoflowers have been used in many areas including catalysis, electronics, and analytical chemistry, and recently, research breakthroughs have led to hybrid inorganic-organic nanoflowers containing various enzymes as organic components.
The hybridization with inorganic materials greatly enhances enzymatic activity, stability, and durability compared to the corresponding free enzymes, but the formation of protein nanocrystals requires high heat treatment, limiting the loading capacities of intact DNA.
SEM images show the effect of the DNA sequence and length of the formation of DNA-nanoflowers. (A) dNTPs (100 mM), (B) adenine-richssDNA (0.25 mM), (C) thymine-rich ssDNA (0.25 mM), (D) guanine-rich ssDNA(0.25 mM), (E) cytosine-rich ssDNA (0.25 mM), (F) A-T dsDNA (51 bp; 0.25 mM),(G) G-C dsDNA (51 bp; 0.25 mM), (H) PCR amplicon (200 bp; 600 nM),(I) plasmid DNA (5420 bp; 20 nM), and (J) genomic DNA (4857 kbp; 10 pM). Credit: KAIST
KAIST researchers addressed the issue, focusing on the fact that nucleic acids with well-defined structures and selective recognition properties also contain amide and amine groups in their nucleobases.
They proved that flower-like structures could be formed by using nucleic acids as a synthetic template, which paved the way to synthesize the hybrid nanoflowers containing DNA as an organic component in an eco-friendly condition.
The researchers also confirmed that this synthetic method can be universally applied to any DNA sequences containing amide and amine groups.
(A) Schematic illustration of the formation of nuclease-resistant DNA-inorganic nanoflowers.(B) SEM images showing time-dependent growth of DNA-nanoflower. Credit: KAIST
They reckon their approach is unique considering that the majority of previous works focused on the utilization of DNA as a linker to assemble the nanomaterials.
The hybrid nanoflowers enabled the sensitive detection of various molecules including phenol, hydrogen peroxide, and glucose.
DNA-copper nanoflowers showed even higher peroxidase activity than those of protein-copper nanoflowers, which may be due to the larger surface area of the flower- shaped structures, creating a greater chance for applying them in the field of sensing of detection of hydrogen peroxide.
The research team expects that their research will create diverse applications in many areas including biosensors and will be further applied into therapeutic applications.
As Park says: “The inorganic component in the hybrid nanoflowers not only exhibits low cytotoxicity, but also protects the encapsulated DNA from being cleaved by endonuclease enzymes. Using this feature, the nanostructure will be applied into developing gene therapeutic carriers.”
Research is published in Journal of Materials Chemistry B.