Diatom-based biosynthesis of gold-silica nanocomposite and their DNA binding affinity

作者：Roychoudhury Piya; Nandi Camellia; Pal Ruma^*

来源：Journal of Applied Phycology, 2016, 28(5): 2857-2863.

DOI：10.1007/s10811-016-0809-4

• Diatom
• Gold-silica nanocomposite
• Gold-silica DNA
• Transmission electron microscopy

We report an eco-friendly method for biosynthesis of gold-silica (Au-SiO2) nanocomposite using a diatom, Amphora copulata, as reducing agent. The live cells of Amphora covered by siliceous frustules reacted with hydrogen tetra-auro chlorate (HAuCl4), and Au-SiO2 particles were synthesized after 72 h of reaction. Energy-dispersive X-ray (EDAX) analysis confirmed the presence of Au and SiO2 nanoparticles in a composite form, and their characterization was done by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and scanning (SEM) and transmission (TEM) electron microscopy. The SEM study revealed that composite particles were deposited on the siliceous frustules of live cells, whereas in dead diatom cells, the surface remained unchanged. The TEM analysis confirmed the synthesis of triangular-, spherical-, and hexagonal-shaped Au-SiO2 particles with 5 to 45-nm size range. Biogenic Au-SiO2 nanoparticles were tested for DNA binding affinity by agarose gel electrophoresis and TEM study after 30 min of interaction with isolated DNA from the green alga, Pithophora. The synthesized nanoparticles were found to bind with DNA molecules without any surface modification. The TEM images of Au-SiO2 particles, taken after interaction with DNA, showed the arrangement of particles in specific manner which formed a "Y"-shaped, chain-like, and coiling structure, indicating that the diatom-based bio-synthesized Au-SiO2 particles were very efficient in binding with DNA which could be applied in the bio-medical field directly.

• 出版日期2016-10