Molecular interactions on InxGa1-xN

Abstract

Atomic force microscopy in solution offers a platform for assessing interactions on chemically modified surfaces. In this study a biologically relevant molecule, an amino acid, is adsorbed onto a compositionally varied semiconductor substrate. AFM is used to assess the effect of the substrate composition on the adhesion of the amino acid. We report adsorption of L-arginine to an indium-gallium-nitride (InGaN) substrate with a gradient of In:Ga composition. Data are collected above and below the isoelectric point of arginine to highlight the effect of protonation on the adhesive behavior across the InGaN. Characterization is also performed using X-ray photoelectron spectroscopy to establish the presence of amino acid on the surface and determine the general composition of a given region of the substrate both with and without amino acid. Combining these factors, we are able to better evaluate the significance of substrate properties in influencing the behavior of surface molecules. Determining the dynamics of amino acid behavior as a function of both the substrate and the environment provides new insight into the preparation of semiconductor materials for biological applications. © The Society for Experimental Mechanics, Inc. 2014.