Use of spectroscopic and zeta potential techniques to study the interaction between lysozyme and curcumin in the presence of silver nanoparticles at different sizes.

This article describes, for the first time, the effect of three different sizes of silver nanoparticles on the binding of curcumin to lysozyme as examined by spectroscopic and zeta potential techniques at physiological conditions. The binding constants of curcumin to lysozyme in the presence of silver nanoparticles were measured. Based on the results of synchronous fluorescence and three-dimensional fluorescence spectroscopy, the presence of the different sizes of silver nanoparticles caused conformational changes in lysozyme during the binding of curcumin. Such changes were also observed when increasing the curcumin concentration. The results of fluorescence resonance energy transfer theory indicated that different sizes of silver nanoparticles could change the binding distance between curcumin and lysozyme. Based on the red edge excitation shift approach, we concluded that the limited mobility around the Trp residues decreased in the presence of silver nanoparticles with bigger size. Under resonance light scattering, the aggregation of curcumin on lysozyme in the presence of silver nanoparticles can play a major role in functional proteins. Communicated by Ramaswamy H. Sarma.