Visible‐Light‐Induced Directed Gold Microwires by Self‐Organization of Nanoparticles on Aspergillus Niger

Abstract

A directional point‐to‐point growth of microwires of gold nanoparticles (AuNPs) self‐organized on Aspergillus niger (A. niger) templates by utilizing positive phototropic fungal response to different spectral ranges of visible light is reported. A. niger serves as a living template for the self‐organization of monosodium glutamate (MSG) capped gold colloids under controlled nutrient trigger and appropriate light, temperature, and humidity conditions. The experimental results show that control of these parameters eliminates the need for any microchannels for the directional growth of microwires. The growth rate of fungal hyphae increases exponentially under light illumination compared to its growth in the dark under similar conditions. White light is found to be most suitable to trigger the directional growth. Gold microwires of about 1 to 2 μm diameter and length exceeding 1 mm are grown within a week with a maximum divergence of 40–50° from the light path regardless of the wavelength of the light irradiation. Phototropic response of fungi has been investigated intensively over the last three decades, but this is the first report on the collective use of microbial tropism and directed biomimetic self‐organization of metallic nanoparticles on living organisms.

Physarum wires: Self-growing self-repairing smart wires made from slime mould

“…In present paper we outline our scoping experimental results on evaluating properties of protoplasmic tubes as electrical wires. Our finding discussed in the paper complement previous studies on fabrication of organic wires and using living substrates to grow metallised conductive pathways: self-assembling molecular wires [54,44], DNA wires [16], electron transfer pathways in biological systems [32], live bacteria templates for conductive pathways [17], bio-wires with cardiac tissues [18], golden wires with templates of fungi [45].…”

Heterogeneous Microtubules of Self-assembled Silver and Gold Nanoparticles Using Alive Biotemplates

“…It is possible that subsequent multilayers were formed due to the entropic contribution while the Brownian motion was responsible for the nanoparticles migration from the medium to the hyphae surface. 22 However, these successive layers cannot be simply explained in terms of chemical bonds between nanoparticles and the fungus. Therefore, some attractive interaction should occur between these nanoparticles mediated by molecules secreted by the fungus [23][24][25] .…”

“…[11][12][13][14][15] Heterostructures consisting of multilayers with controlled thickness have been constructed owing to interactions between nanoparticles and biotemplates. 16,17 Particularly, fungi can be effectively used as biotemplates since they are skilled at adapting in distinct environments. This versatility extends to their peculiar shapes, ranging from mushrooms to microfilaments.…”

Inhibition of Aspergillus oryzae Mycelium Growth and Conidium Production by Irradiation with Light at Different Wavelengths and Intensities

“…Besides, improvement of acid protease production was found in the mixed culture of A. niger and A. oryzae using solid-state fermentation ( 32 ). Studies have also shown that A. niger has a positive photogenic response to white light ( 33 ), and the production of conidia and glucoamylase was promoted by continuous illumination with blue light ( 34 ). Considering blue light inhibited the mycelial growth and conidiation of A. oryzae GDMCC 3.31, blue light can be used to regulate the koji of a mixed strain of A. oryzae and A. niger .…”