Spectroscopic investigation on the sonodynamic damage to protein in the presence of eosine B

• The sonodynamic damage to protein in presence of EB was investigated.
• The synergistic effects of ultrasound and EB can efficiently damage the protein.
• The damage of protein could be mainly due to the generation of ROS.
• The nitro and bromine substituent groups increase the quantity of ROS.
• EB possesses more excellent sonodynamic activity than FS.

In this work, bovine serum albumin (BSA) and eosine B (EB) were selected as a model protein and sonosensitizer, respectively. The sonodynamic damage to protein in the presence of EB and its mechanism were studied by means of absorption and fluorescence spectra. The results indicated that the synergistic effects of ultrasound and EB can efficiently damage the BSA molecules, and the damage of protein could be mainly due to the generation of reactive oxygen species (ROS). The damage degree of protein increased with the increase of ultrasonic time and EB concentration because of the increased quantities of ROS. Hydroxyl free radical (OH) was the major mediators of the ultrasound-inducing proteins damage in the presence of EB. In addition, the quantities of ROS from the diphenylcarbazide (DPCI)–EB solutions and the DPCI–fluorescein (FS) solutions with or without ROS scavengers were contrasted, respectively. The results show that FS mainly produce OH, but the quantities of ROS in the presence of FS were lower than those of EB, which indicates that the nitro and bromine substituent groups on the benzene ring of FS increase the quantity of ROS, but do not change the kinds of ROS.