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Adsorption and Orientation of the Physiological Extracellular Peptide Glutathione Disulfide on Surface Functionalized Colloidal Alumina Particles
- Meder, Fabian, Hintz, Henrik, Koehler, Yvonne, Schmidt, Maike M., Treccani, Laura, Dringen, Ralf, Rezwan, Kurosch
- Journal of the American Chemical Society 2013 v.135 no.16 pp. 6307-6316
- adsorption, aluminum oxide, colloids, disulfide bonds, glutathione, models, phosphates, sorption isotherms, zeta potential
- Understanding the interrelation between surface chemistry of colloidal particles and surface adsorption of biomolecules is a crucial prerequisite for the design of materials for biotechnological and nanomedical applications. Here, we elucidate how tailoring the surface chemistry of colloidal alumina particles (d₅₀ = 180 nm) with amino (−NH₂), carboxylate (−COOH), phosphate (−PO₃H₂) or sulfonate (−SO₃H) groups affects adsorption and orientation of the model peptide glutathione disulfide (GSSG). GSSG adsorbed on native, −NH₂-functionalized, and −SO₃H-functionalized alumina but not on −COOH- and −PO₃H₂-functionalized particles. When adsorption occurred, the process was rapid (≤5 min), reversible by application of salts, and followed a Langmuir adsorption isotherm dependent on the particle surface functionalization and ζ potential. The orientation of particle bound GSSG was assessed by the release of glutathione after reducing the GSSG disulfide bond and by ζ potential measurements. GSSG is likely to bind via the carboxylate groups of one of its two glutathionyl (GS) moieties onto native and −NH₂-modified alumina, whereas GSSG is suggested to bind to −SO₃H-modified alumina via the primary amino groups of both GS moieties. Thus, GSSG adsorption and orientation can be tailored by varying the molecular composition of the particle surface, demonstrating a step toward guiding interactions of biomolecules with colloidal particles.