Direct reagentless detection of the affinity binding of recombinant His-tagged firefly luciferase with a nickel-modified gold electrode

The direct reagentless electrochemical detection of recombinant firefly luciferase binding with gold electrode modified with nickel ions has been carried out. Self-assembly of molecules of functional disulfide containing chelating moieties on the gold electrode was monitored by contact angle measurements and confirmed by electrochemical data as three times decrease of electric double layer capacitance. Succeeding nickel ions chelating followed by selective binding of target protein were registered by reagentless electrochemical measurements as consistent decreases of double layer capacitance. The quantification of bound protein has been achieved by means of luminescent assay of residual enzymatic activity in solution for electrode recovery. The electrode surface coverage by protein globules has been confirmed by AFM.