A Molecular Picture of the Adsorption of Glycine in Mesoporous Silica through NMR Experiments Combined with DFT-D Calculations

Abstract

The adsorption behavior of the amino acid glycine in mesoporous silica has been investigated using a combination of quantum chemical calculations and NMR spectroscopy experiments. Glycine adsorption on two representative sites of an amorphous silica surface, vicinal silanols and a silanol nest, was investigated by DFT-D. The effect of water coadsorption on the energetics of adsorption and NMR shifts was characterized. It was found that the silanol nest is a more favorable site for glycine adsorption due to a local increased H-bond density. Co-adsorption with water is also favored, especially a water molecule between a SiOH and the ammonium moiety. NMR chemical shifts computed on these models fall into the observed 13 C and 15 N experimental range, suggesting that the presence of different energetically comparable adsorption configurations cannot be excluded.

Modeling and simulation of protein–surface interactions: achievements and challenges

“…Various corrections have been proposed to solve this problem (Tkatchenko et al 2010), and some of them have also been tested in the framework of protein-surface interactions with encouraging results. In particular, the DFT-Dn methods (Grimme, 2004;Grimme et al 2010;Wu et al 2001) (that add to the DFT energy, empirical atom-atom d −6 terms, where d is the pairwise interatomic distance, suitably damped for small d) have been used for amino acid and peptide adsorption on mineral surfaces (Folliet et al 2013;Rimola et al 2009) and on graphene (Akdim et al 2013). The f xc functional, vdW-DF, which does not contain empirical terms (Dion et al 2004), has been tested against experimental desorption energy data for some small molecules on Au(111) (Wright et al 2013a).…”

Molecular Picture of the Adsorption of Ibuprofen and Benzoic Acid on Hydrated Amorphous Silica through DFT-D Calculations Combined with Solid-State NMR Experiments

“…10 This property leads to the reduction of drug dosage and potential side-effects. A comprehension at the molecular level of the interactions involved in the adsorption phenomenon of ibuprofen onto the silica surface could lead to improve the conception of amorphous silica-based pharmaceutical vectors through a better control of the drug release over time 11 . Recent progress in structural studies of active pharmaceutical ingredients embedded in different drug carriers in the application of solidstate NMR spectroscopy has been reviewed by Skorupska et al 12 Ibuprofen release rate is related to the mesoporous silica's structural parameters and to the affinity between the molecule and the silica surface.…”

Theoretical model of the interaction of glycine with hydrogenated amorphous carbon (HAC)

“…We selected either the so-called dispersion corrected DFT (d-DFT) method, 30 or the Grimme DFT-D2 approach. 16,32 The generalized gradient approximation (GGA) has been employed with two different types of functionals, PBE 33 and PW91. 16,32 The generalized gradient approximation (GGA) has been employed with two different types of functionals, PBE 33 and PW91.…”

“…13,14 A usual way of preparing HAC films in the laboratory is through plasma enhanced chemical vapor deposition (PECVD) of suitable gas precursors. [16][17][18][19][20] These investigations have allowed a precise characterization of the biomolecule/surface systems at the microscopic level. 11 The interaction of the neutral and ionic forms of glycine (Gly) with the surfaces of metals and oxides has been recently studied using Density Functional Theory (DFT) methods.…”