Gold Nanocluster Protection of Protein from UVC Radiation: A Model Study on Bovine Serum Albumin.

Harmful UVC (200-280 nm) radiation is entirely screened by a combination of dioxygen and ozone in the stratosphere. However, because of environmental pollution, depletion of stratospheric ozone layer is increasing alarmingly, ensuing danger of penetration of the harmful UVC through the earth's atmosphere to reach the living world. Studies have shown that UVC radiation accelerates aging of albumin solutions along with other qualitative changes. Herein, we have used in situ grown and ex situ added gold nanoclusters (AuNCs) to minimize the damage in the protein structure caused by long-term UVC exposure. The effects were demonstrated in the absence and presence of lipid vesicles to mimic the biological environment. Bovine serum albumin (BSA) has been used as the model protein that contains ∼50-60% helicity. It is observed that UVC converts most of α-helix into β-sheet, leading to the aggregation of protein. The ingrown AuNCs could provide about 23-40% protection to the secondary structure, whereas the externally added AuNCs preserved almost 73-82%. To generalize this finding, we have also studied the effect of AuNC protection on the UVC-exposed lysozyme protein. The results show that the proposed method is indeed helpful for life.