This study elucidates that the protein reorientation on a chip can be changed by an external electric field (EEF) and optimised for achieving strong effective binding between proteins. Protein A and its binding protein immunoglobulin G (IgG) were used as an example, in addition to an anticancer peptide (CB1a) and its antibody (anti-CB1a). The binding forces (BFs) were measured by atomic force microscopy (AFM) with EEFs applied at different angles (EEF degrees). The optimal angle (OA) of the EEF (OAEEF degrees) corresponding to the maximum binding force (BFmax) was obtained. The results showed that the BFmax values between IgG/Protein A and anti-CB1a/CB1a were 6424.2 +/- 195.3 pN (OAEEF degrees = 45 degrees) and 729.1 +/- 33.2 pN (OAEEF degrees = 22.5 degrees), respectively. Without an EEF, the BF values were only 730.0 +/- 113.9 pN and 337.3 +/- 35.0 pN, respectively. Based on these observations, we concluded that the efficient optimisation of protein-protein interaction on a chip is essential. This finding is applicable to the industrial fabrication of all protein chips.
- LOCAL STABILITY IDENTIFICATION; ATOMIC-FORCE MICROSCOPY; IMMOBILIZATION; BIOMOLECULES; NANOBIOCHIPS; RECOGNITION; SUPPORTS; ANTIBODY; CELL