Fig. 1.

Biosynthesis of AuNPs using Tricholoma crassum and spectroscopic analysis. a Color change during reaction. A 20 mM solution of HAuCl₄. B Mycelia-free cell filtrate of Tricholoma crassum. C 1 mM HAuCl₄ with 24 h cell filtrate for 1 h showing violet color indicating synthesis of AuNPs. b UV-vis spectra of the AuNPs synthesized with different incubation periods (24, 48, 72 h). Solid arrow shows absorption peak at 552 nm for 24 h incubation period. Dashed arrow shows slight red shift of the absorption maxima with increase in incubation period. c AuNPs synthesized under different pH showing different colors. d UV-vis spectra of the same. Solid arrow shows absorption peak at 552 nm for pH 5.5 and dashed arrow indicates blue shift of absorption maxima with increase in pH