Zinc Interactions with Glucosamine-Functionalized Fused Silica/Water Interfaces

Abstract

The adsorption of Zn2+ to glucosamide-functionalized fused silica/water interfaces is studied using second harmonic generation (SHG). We characterize each step of the surface functionalization using vibrational sum frequency generation (SFG) and X-ray photoelectron spectroscopy (XPS), where specific vibrational modes in the C−H region and binding energies in the C1s and N1s region are determined to be indicative of glucose covalently tethered to the surface. We employ the SHG χ(3) technique to track Zn2+ adsorption and desorption directly at the glucosamide-functionalized fused silica/aqueous interface at pH 7 and 10 mM NaCl and determine the electrostatic and thermodynamic binding parameters using standard electrical double layer models to quantify the change in interfacial potential upon zinc adsorption. The results presented here allow for the possibility of 2:1 to 3:1 carbohydrate:metal coordination complexes and suggest the possibility for multivalent interactions which have not been observed with glucose in the bulk aqueous phase, where 1:1 complexes dominate. These findings suggest that interactions between metal ions and carbohydrate arrays may be much stronger at interfaces as opposed to the bulk phase, with direct implications for controlling and predicting coordination chemistry.

Successive Surface Reactions on Hydrophilic Silica for Modified Magnetic Nanoparticle Attachment Probed by Sum-Frequency Generation Spectroscopy

“…Second-order nonlinear spectroscopic techniques can be employed to characterize these modified surfaces and interfaces. For instance, many studies have utilized modified silica substrates for anion (CrO 4 2– ) or cation (Ca 2+ , Cd 2+ , and Zn 2+ ) interactions at the buried solid–water interface using nonlinear optical second harmonic generation (SHG) spectroscopy. − The SHG signals vary depending on the interaction of the adsorbed ion species with the modified surfaces under certain conditions. − The silica substrates were initially functionalized with synthesized ester-terminated silanes and then hydrolyzed to obtain carboxy-terminated monolayers. − Additionally, SFG spectroscopy, a surface-sensitive technique with molecular sensitivity, has been utilized to monitor the conversion process. ,, Apart from the hydrolysis of ester, other SFG studies have been performed to characterize surface click reactions. , Chen et al functionalized glass substrates using commercially available aminophenyl, which was then converted to azidophenyl groups by the oxidation reaction. To test the efficiency of copper-catalyzed azide-acetylene cycloaddition on the prepared azidophenyl-terminated substrates, they employed small terminal alkyne molecules, including acetylene-modified single-strand DNA, and analyzed the surfaces before and after reaction using X-ray photoelectron spectroscopy, fluorescence spectroscopy, and SFG spectroscopy …”

“…19−25 Additionally, SFG spectroscopy, a surfacesensitive technique with molecular sensitivity, has been utilized to monitor the conversion process. 21,24,25 Apart from the hydrolysis of ester, other SFG studies have been performed to characterize surface click reactions. 5,26 Chen et al functionalized glass substrates using commercially available aminophenyl, which was then converted to azidophenyl groups by the oxidation reaction.…”

Investigating the Coordination/Binding Events of Biologically Relevant Monosaccharides with New Mononuclear Iron(III) and Zinc(II) Complexes in Aqueous Solution

“…Saccharides are, in general, very versatile ligands due to the presence of multiple donor sites of nearly equivalent oxygen atoms as well as the equilibria between several isomers. In earlier, few research groups have contributed immensely to the growth of the subject of transition metal‐saccharide chemistry by developing the synthetic routes for Cr(III), VO(II), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), and MoO 2 (II) saccharide complexes. The focus of this paper is on the interactions of monosaccharides with new iron(III) and zinc(II) complexes of a carboxyamine functionalized tridentate ligand, N‐(2‐pyridylmethyl)‐β‐alanine (Hpbal), in alkaline aqueous solution.…”

Synthesis, crystal structure and investigation of mononuclear copper(II) and zinc(II) complexes of a new carboxylate rich tripodal ligand and their interaction with carbohydrates in alkaline aqueous solution

“…Recently, some synthetic receptors have been used to investigate carbohydrate recognition in relation to the important roles they play in biological processes [3,4]. One of such recognition which is being investigated with ever increasing interest includes simple metal ions in carbohydrate interactions [6–13]. This particular interaction has important implications in a variety of biological systems such as support in membrane systems, cell–cell adhesion, intercellular recognition, signal transduction, fertilization, and as targets of bacterial or viral infections of cells [1–5].…”

“…In the past several years, the study of carbohydrate–transition metal ion interactions in chemistry and biology has been pursued by several research groups [2,14–16,24, 29–32]. For example, synthetic strategies for VO 2+ , Cr 3+ , Mn 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , and ${\text{MoO}}_2^{2+}$ carbohydrate complexes have been developed [6,7,11–14,28,31–36]. Furthermore, the biologically relevant aspects of carbohydrate complexes of Fe 3+ , Cr 3+ , VO 2+ , and Zn 2+ , have also been reported [32–35,37–43].…”