Growth of templated gold microwires by self organisation of colloids on Aspergillus niger

• Template assisted self-organization of inorganic nanoparticles was investigated to render the physicochemical properties of both nanoparticles and biological materials in hierarchical architecture by using chloroauric acid and Ajinomoto® (mono-sodium glutamate, MSG) that served the dual purpose of stabilizing the NPs in the gold colloid and also nutritional source for growth of Aspergillus niger (A. niger) hyphae and mycelia (acting as living template). The coating of gold nanoparticles on living hyphae was controlled by varying MSG concentration to gold salt and the reaction temperature without requiring any hazardous re-agent. Grown microwires displayed wide variations in dimension and morphology depending upon the preheating and nutrient conditions. Uniform and thick agglomeration of gold nanoparticles at higher molar ratios (MR's ~ 10 and 12) formed microwire of diameters between 1-2 μm and length exceeding 1 mm within two weeks. Heat treatment above 40-45°C led to negligible growth, wide variation in diameter (1.1-3.6 μm) and significant reduction of gold colloids due to excessive surface evaporation, whereas, maximum morphological changes in microwires were observed at 300C, having diameter 2.1-2.9 μm. The pH of the gold colloids was found to change gradually from 3 to > 7 during the growth process indicating the successive aggregation of gold nanoparticles on living hyphae and the consumption of glutamic acid by the microbes. High surface area of these bio-templated gold microwires is interesting for sensing, electronics, optics and catalysis applications.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Nanoteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Nano-technology (hsv//eng)

Keyword

Aspergillus niger

Colloid

Gold microwire

Microbial template

Self-organization

Fungi

Publication and Content Type

ref (subject category)

art (subject category)