Thermodynamically reversible addressing of a stimuli responsive fusion protein onto a patterned surface template

The sensitivity of an elastin-like polypeptide (ELP) to environmental stimuli is used to reversibly immobilize a fusion partner, thioredoxin (TRX), onto a hydrophobic surface. An ELP, fused to TRX at its C-terminus, adsorbs onto a hydrophobic self-assembled monolayer (SAM) on gold above its inverse phase transition temperature (T-c) and is resolubilized from the surface when the solution temperature is lowered below T-c. We show that the adsorbed fusion partner TRX is recognized by an antibody specific to TRX and that the complex is also resolubilized from the surface below T-c. Adsorption of TRX-ELP is inhibited by hydrophilic surfaces that are defect-free. In situ ellipsometry shows that the ELP-anchored TRX adsorbs above T-c up to a well-defined layer thickness that is greater than a monolayer and that the adsorption and desorption cycle can be repeated. These results are confirmed by atomic force microscopy and by surface plasmon resonance spectroscopy. The preferential adsorption of TRX-ELP on hydrophobic surfaces is used to create a pattern of adsorbed protein on a surface composed of a pattern of hydrophobic and hydrophilic SAMs on gold. We term this method to reversibly address an ELP fusion protein to chemically distinct regions of a patterned surface by an external stimulus "thermodynamically reversible addressing of proteins" (TRAP).