Silicone oil is a chemically inert and biocompatible material. However, the use of silicone oil as an adjunct for internal tamponade in the treatment of retinal detachment is accompanied by the sequelae of cataract, the molecular mechanism of which has been a mystery for scientists. In this study, we focused on the influence of silicone oil on the aggregating behaviors of one of the important proteins in the eyes, alpha B-crystallin (CRYAB). We found that silicone oil could promote the amyloid-like aggregation of CRYAB, verified using atomic force microscopy (AFM), transmission electron microscopy (TEM), laser granularity and number analysis (Nanosight), and turbidity measurements. Furthermore, fluorescent experiments using Thioflavin T (ThT), Congo red, and 1-anilinonaphthalene-8-sulfonic acid (ANS) suggested formation of a beta-sheet structure in CRYAB in the presence of silicone oil, which was also confirmed by far-UV circular dichroism (CD) spectroscopy. These findings provide a direct evidence of the changes in the secondary structures of CRYAB protein and amyloid aggregation behavior upon adding silicone oil in the solution, and could be helpful for understanding the molecular mechanisms of the cataract formed in silicone oil-filled eyes.
