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Copper immobilized on silk fibroin was successfully prepared and fully characterized using powder X-ray diffraction, scanning electron microscopy-energydispersive X-ray spectroscopy, Fourier transform-infrared, CHN elemental analysis, and inductively coupled plasma-atomic emission spectroscopy. Catalytic activity of this catalyst was examined in the azide-alkyne cycloaddition reaction with internal and terminal alkynes at room temperature under mild conditions. The reusability of the heterogeneous supported Cu catalyst was examined four times without significant loss of catalytic activity.

A palladium-fibroin complex (Pd/Fib.) was prepared by the addition of sonicated fibroin fiber in water to palladium acetate solution. Pd (OAc) 2 was absorbed by fibroin and reduced with NaBH 4 at room temperature to the Pd(0) nanoparticles. Powder-X-ray diffraction, scanning electron microscopyenergy-dispersive X-ray spectroscopy, Fourier transform-infrared, CHN elemental analysis and inductively coupled plasma-atomic emission spectroscopy were carried out to characterize the Pd/Fib. catalyst. Catalytic activity of this finely dispersed palladium was examined in the Heck coupling reaction.The catalytic coupling of aryl halides (-Cl, -Br, -I) and olefins led to the formation of the corresponding coupled products in moderate to high yields under air atmosphere. A variety of substrates, including electron-rich and electronpoor aryl halides, were converted smoothly to the targeted products in simple procedure. Heterogeneous supported Pd catalyst can be recycled and reused several times.

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