*3.1. Materials*

HSA (fatty acid-free) and HpzA (42643) were purchased from Sigma-Aldrich Co. (St. Louis, MO, USA). We used double distilled for the preparation of all buffers. HSA stock solution (75 µM) was made in 20 mM sodium phosphate buffer, pH 7.4. Appropriate blanks were used as control, and the reported spectra are the subtracted spectra. We used analytical grade chemicals for buffer preparations.
