Analysis of blood proteins on protein arrays with a spectral surface plasmon resonance biosensor

We investigated whether blood proteins can be analyzed on protein arrays with a spectral surface plasmon resonance (SPR) biosensor. We modified gold arrays with a mixture of mercaptoundecanoic acid and mercaptohexanol, and immobilized blood proteins-hemoglobin (Hb) and haptoglobin (Hp), or their antibodies. We analyzed interactions of Hb with Hp on protein arrays by measuring the shift of resonance wavelength, and a significant interaction was observed when Hp was used as a ligand. Then, we fabricated antibody arrays with antibodies against Hb and Hp, and analyzed binding of blood proteins onto the arrays. Anti-Hb showed a specific interaction with Hb on the antibody arrays. Interaction of anti-Hp with Hp was specific when Hp was used as capture molecules. The shift of resonance wavelength caused by the interaction of blood proteins was explained by changes of refractive index on the gold surfaces of protein arrays. The present work suggests that spectral SPR biosensors can be used as a useful tool for the analysis of blood proteins on protein arrays.