MBP-Gal-1 chimeric protein immobilization onto GCE functionalized by electrochemical reduction of pyridinium diazonium derivative

Galectin-1 (Gal-1) is a member of galectin family which have an important role in tumor progression and proliferation, angiogenesis, resistance to drugs and masking against recognition by the immune system1. Thus, there is a great interest in the development of biosensors which use Gal-1 as a biomarker for oncological conditions2. In this work, we investigated the oriented immobilization of the chimeric Gal-1 onto glassy carbon electrode (GCE) electrically modified by the pyridinium diazonium salt in situ generate from 1-(4-aminophenethyl)-[4,4’-bipyridin]-1-ium bromide (Fig. 1). The immobilization was performed using Maltose Binding Protein (MBP) as a fused protein to Gal-1 (MBP-Gal-1). The MBP domain exhibits good affinity by the nonquaternized nitrogen from pyridinium derivative film3. Electrochemical Capacitance Spectroscopy (ECS) results indicated that the MBP domain was important for the modified electrode interaction (Fig. 2). Immobilization time and the MBP-Gal-1 concentration were also relevant to the kinetics and the results suggested a monolayer saturation in 40 minutes of interaction, using 1 μmol L-1 MBP-Gal-1 (Fig. 2 and 3 A). Lactose detection experiments indicated that Gal-1 activity was preserved after immobilization (Fig. 3 B). Therefore, the chimeric protein presented adequate orientation and maintained its activity after immobilization, indicating that the system is promising for the development of Gal-1 biosensor.