Open AccessA Thermodynamic Description of the Adsorption of Simple Water-Soluble Peptoids to Silica
Author(s) -
Anna L. Calkins,
Jennifer Yin,
Jacenda L. Rangel,
Michel Landry,
Amelia A. Fuller,
Grace Y. Stokes
Publication year - 2016
Publication title -
langmuir
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.042
H-Index - 333
eISSN - 1520-5827
pISSN - 0743-7463
DOI - 10.1021/acs.langmuir.6b02804
Subject(s) - peptoid , adsorption , chemistry , circular dichroism , molecule , cationic polymerization , binding constant , langmuir adsorption model , organic chemistry , crystallography , peptide , binding site , biochemistry
The first report of a water-soluble peptoid adsorbed to silica monitored by second harmonic generation (SHG) at the liquid/solid interface is presented here. The molecular insights gained from these studies will inform the design and preparation of novel peptoid coatings. Simple 6- and 15-residue peptoids were dissolved in phosphate buffered saline and adsorbed to bare silica surfaces. Equilibrium binding constants and relative surface concentrations of adsorbed peptoids were determined from fits to the Langmuir model. Complementary fluorescence spectroscopy studies were used to quantify the maximum surface excess. Binding constants, determined here by SHG, were comparable to those previously reported for cationic proteins and small molecules. Enthalpies and free energies of adsorption were determined to elucidate thermodynamic driving forces. Circular dichroism spectra confirm that minimal conformational changes occur when peptoids are adsorbed to silica while pH studies indicate that electrostatic interactions impact adsorption.