Albumin adsorption on Cibacron Blue F3G-A immobilized onto oligo(ethylene glycol)-terminated self-assembled monolayers

Self-assembled monolayers can be tailored with specific ligands to a certain protein and at the same time prevent the non-specific adsorption of other proteins. Cibacron Blue F3G-A (CB-thiol) was successfully immobilized onto tetra(ethylene glycol)-terminated alkanethiol (CB-thiol). The affinity of human serum albumin (HSA) to immobilized Cibacron Blue F3G-A was studied using mixed thiolate self-assembled monolayers on gold with different n-alkyl chain lengths and functional terminal groups (CH₃-; OH- and tetra(ethylene glycol)). Surfaces were characterized using X-ray photoelectron spectroscopy and water contact angle measurements. Albumin adsorption and exchangeability of the adsorbed albumin molecules with other albumin molecules in solution were evaluated using ¹²⁵I-radiolabeled HSA. Competitive adsorption between albumin and fibrinogen to the different self-assembled monolayers (SAMs) was also investigated. Results showed that the incorporation of CB-thiol on the monolayers does not increase the HSA adsorption and reversibility on the SAMs. However, although specific adsorption of HSA to the immobilized Cibacron Blue F3G-A was not demonstrated, the presence of CB-thiol decreases the affinity of fibrinogen to the OH-terminated SAMs.