Determination of glycosylated albumin using surface plasmon resonance sensor

The determination of glycosylated albumin (GA) based on an SPR apparatus was performed using the bond formation of GA with boronic acid functional groups on a sensor chip. In order to develop a sensor chip that can reduce non-specific adsorption, the surfaces of gold-evaporated chips were chemically modified by forming self-assembled monolayers (SAMs) of five kinds of thiol compounds. It was confirmed that the sensor chip modified with an ethylene glycol (EG) terminated SAM showed the best results for reducing non-specific adsorption among the examined SAMs. It was found that the sensor chip can reduce the adsorption of proteins of different molecular weights and isoelectric points in serum. Based on these results, the ratio of alkyl thiols having EG and carboxylic acid terminals was optimized in order to prepare a new SPR sensor chip that can immobilize the sensing molecules while preventing non-specific adsorption. In this study, 4-aminophenyl boronic acid was fixed through amido bond formation on a mixed SAM sensor chip while aiming at the quantification of diol compounds. The SPR sensor using this sensing chip could determine GA, which is an example of a sugar-protein, in the concentration range of 7.5-20% (total amount of albumin).