Investigation on the effect of zinc oxide nanoparticles in the aggregation of hen egg lysozyme

Abstract

Protein misfolding and aggregation are responsible for several human pathologies commonly known as protein misfolding diseases. The various examples of protein misfolding diseases are: Alzheimer disease, spongiform encephalopathy, diabetes type 2, serpin-deficiency disorder, Huntington disease, Parkinson disease, amyloid polyneuropathy, and several others. The current research work was carried out to investigate the potential of ZnO nanoparticle to prevent lysozyme aggregation. ZnO nanoparticles were synthesized by chemical precipitation method from Zinc acetate dihydrate and urea. The optical, morphological and structural properties of synthesized ZnO nanoparticles have been studied using UV-Vis spectrophotometer, SEM, DLS, XRD and EDS. UV-Vis spectroscopic study shows that ZnO nanoparticles have surface plasmon resonance at 375nm. DLS analysis shows the average size of synthesized ZnO nanoparticle to be 68 nm. The EDS analysis shows the elemental composition of synthesized ZnO naoparticles and XRD study confirms the wurtzite structure of ZnO nanoparticles. The lysozyme aggregation was prepared by heating the native lysozyme at 1000C. The effect of ZnO nanoparticles on the aggregation of lysozyme was studied. DLS analysis shows the mean size of the aggregates decreases with increasing concentration of ZnO nanoparticle (NP), which was further confirmed by SEM analysis. UV-Vis and Fluorescence spectroscopic studies were performed to analyze the structural changes of lysozyme upon binding with nanoparticles. The Congo red assay was performed to study the formation of amyloid fibrils.