The paper reports a new “soft” surface functionalization strategy, based onto highly selective ion metal chelation process. The proposed stepwise methodology implies at firstthe construction of a monolayer of terpyridine-based thiols (Tpy), whose highly packedstructuring has been followed in situ by using quartz crystal microbalance (QCM-D)measurements, showing that the monolayers consist of about 2.7×1014 Tpy/cm2. Then, the tridentate sites of the each Tpy moiety are employed to partially chelate divalent metal ions, providing an effective platform to anchoring proteins by completing the metal ion coordination with an available site on the protein of interest. We report the case study of the application of the process to the HSA immobilization onto various surfaces, including Tpy-Fe(II)- and Tpy-Cu(II)-complexes, as well as hydrophilic bare gold substrates and hydrophobic self-assembled Tpy–based monolayers. It is shown that the chelation interaction between Tpy-Cu(II)-complexes andHSA produces the highest and most robust HSA immobilization, with an adsorbed mass at the steady state of ~ 800 ng/cm2, with respect to an average adsorption of ~ 350 ng/cm2for the other surfaces. Furthermore, Cu(II)-chelated surfaces seem promoting a sort of protein “soft” landing, preventing the ubiquitous surface-induced major unfolding and transmitting an orientationinformation to the protein, owing to the highly specific symmetry coordination of the Tpy-Cu(II)-protein complex. Indeed, the interaction with a specific monoclonal antiboby (anti-HSA)indicated the lack of a significant protein denaturation, while a massivereorientation/denaturation process was found for all the remaining surfaces, including the Tpy-Fe(II)-complex. Finally, the metal ion-dependent HSA immobilization selectivity has been exploited to obtain micropatterned surfaces, based on the strikingly different strength ofinteraction and stability observed for Fe(II)- and Cu(II)-complexes.

Chelating Surfaces for Native State Protein Patterning: the Human Serum Albumin Case

TUCCITTO, NUNZIO;Zappalà G;LICCIARDELLO, Antonino;MARLETTA, Giovanni
2015

Abstract

The paper reports a new “soft” surface functionalization strategy, based onto highly selective ion metal chelation process. The proposed stepwise methodology implies at firstthe construction of a monolayer of terpyridine-based thiols (Tpy), whose highly packedstructuring has been followed in situ by using quartz crystal microbalance (QCM-D)measurements, showing that the monolayers consist of about 2.7×1014 Tpy/cm2. Then, the tridentate sites of the each Tpy moiety are employed to partially chelate divalent metal ions, providing an effective platform to anchoring proteins by completing the metal ion coordination with an available site on the protein of interest. We report the case study of the application of the process to the HSA immobilization onto various surfaces, including Tpy-Fe(II)- and Tpy-Cu(II)-complexes, as well as hydrophilic bare gold substrates and hydrophobic self-assembled Tpy–based monolayers. It is shown that the chelation interaction between Tpy-Cu(II)-complexes andHSA produces the highest and most robust HSA immobilization, with an adsorbed mass at the steady state of ~ 800 ng/cm2, with respect to an average adsorption of ~ 350 ng/cm2for the other surfaces. Furthermore, Cu(II)-chelated surfaces seem promoting a sort of protein “soft” landing, preventing the ubiquitous surface-induced major unfolding and transmitting an orientationinformation to the protein, owing to the highly specific symmetry coordination of the Tpy-Cu(II)-protein complex. Indeed, the interaction with a specific monoclonal antiboby (anti-HSA)indicated the lack of a significant protein denaturation, while a massivereorientation/denaturation process was found for all the remaining surfaces, including the Tpy-Fe(II)-complex. Finally, the metal ion-dependent HSA immobilization selectivity has been exploited to obtain micropatterned surfaces, based on the strikingly different strength ofinteraction and stability observed for Fe(II)- and Cu(II)-complexes.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.11769/17204
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