Conformational change of adsorbed and desorbed bovine serum albumin on nano-sized magnetic particles

Adsorptions of bovine serum albumin (BSA) on nano-sized magnetic particles with and without the presence of carbodiimide were studied. Desorption of BSA from magnetic particles were carried out in either NaOH or Na2HPO4 solutions. The structures of native BSA, adsorbed BSA on magnetic particles, and desorbed BSA were studied by several methods, circular dichroism (CD), fluorescence spectroscopy and differential scanning calorimetry (DSC). The magnitude of conformational changes of protein was determined by calculating the alpha-helix content from the circular dichroism (CD) spectra and by evaluating fluorescence spectrum and DSC thermograms. Adsorbed BSA on magnetic particles shows no thermal transition with respect to the native BSA. The structural change of BSA when desorbed by Na2HPO4 solution is much smaller in comparison to that when desorbed by NaOH solution. Hence, this indicates that BSA could be desorbed from nano-sized magnetic particles using Na2HPO4 without much conformational change. (C) 2003 Elsevier B.V. All rights reserved.