Spectroscope and molecular model identify the behavior of doxorubicin-SPION binding to bovine hemoglobin

To provide reference for the bio-safety evaluation of doxorubicin-loaded SPION, the interaction of bovine hemoglobin (BHb) with the drug delivery was investigated by multi-spectroscopic techniques and molecular modeling calculation. Multi-spectroscopic results indicated that DOX-SPION unfolded the conformation of BHb, decreased the content of α-helix from 38.89% to 35.08%, which verified the changes of protein's secondary structure quantificationally. Stern-Volmer analysis and molecular model showed there were two static interaction modes corresponding to the two reaction steps: DOX first immobilized on the particle adhered to the external region of BHb, leading to the increasing exposure of chromophore group, rendering particles to bond to the original hemoglobin central cavity (Site 2) in sequence. They finally generated a stable bioconjugate via hydrogen bonds. This work indicated that the drug delivery has deleterious effects on the frame conformation of BHb, affecting its physiological function.