Development of gold nanoparticle-fungal hybrid based heterogeneous interface for catalytic applications

•Rapid synthesis of catalytically active bio-supported gold nanoparticles.•Fungus acted as machinery for nanoparticle synthesis and immobilization.•Development of “bionanocatalyst” based stable heterogeneous interface.•Sodium borohydride mediated reduction of 4-nitrophenol and hexacyanoferrate(III).•A3 coupling for synthesis of propargylamine from aldehyde, secondary amine & alkyne.

Unsupported and free gold nanoparticles (Au NPs) represent great potential in the field of catalysis. However, shortcomings like agglomeration and loss of the precious catalyst has encouraged the development of supported Au NPs as catalyst with increased activity, selectivity, ease of separation from the reaction mixture and recyclability. The present work demonstrates an eco-friendly, rapid and facile synthesis of catalytically active bio-supported Au NPs using a soil fungus, Aspergillus japonicus AJP01. The dual role of the fungal isolate in synthesis as well as immobilization of Au NPs is the remarkable feature of the study. The fungus successfully reduced Au(III) into Au NPs containing principally Au(0) with a small percentage of Au(I) as revealed by X-ray photoelectron spectroscopy. The particles were spherical in shape and well distributed on fungal mycelia with size ranging predominantly between 15 and 20 nm. The as-synthesized nanoparticle-fungal hybrid was found to be highly efficient in catalyzing sodium borohydride mediated reduction reactions of 4-nitrophenol and hexacyanoferrate(III). The versatility of the bionanocatalyst was further demonstrated by catalyzing the A3 coupling reactions for the synthesis of propargylamines.

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