The application of l-tryptophan functionalized graphene-supported platinum nanoparticles for chiral recognition of DOPA enantiomers

Abstract

A new nanocomposite of L-tryptophan functionalized graphene-supported platinum nanoparticles (L-Trp-rGO@PtNPs) was synthesized utilizing a facile ultrasonic method via p-p conjugate action between graphenesupported platinum nanoparticles and L-tryptophan (L-Trp) molecules. The prepared nanomaterial, which dispersed well in water and presented excellent conductivity, was modified on a glassy carbon electrode (L-Trp-rGO@PtNPs/GCE) for the chiral sensing of DOPA enantiomers. The immobilization process of L-Trp-rGO@PtNPs/GCE was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, ultraviolet-visible (UV-vis) spectrometry and Raman spectroscopy. The electrochemical reactions of DOPA enantiomers were investigated via differential pulse voltammetry. The proposed electrochemical method showed excellent enantiospecificity for DOPA enantiomers and exhibited a stronger enantiospecificity for D-DOPA. In addition, the experimental parameters such as the concentration, the amount of L-Trp-rGO@PtNPs and the pH values were optimized. Under optimum conditions, the linear response ranges for the discrimination of DOPA were from 5.0 Â 10 À8 to 5.0 Â 10 À3 mol L À1 with a detection limit of 1.7 Â 10 À8 mol L À1 (S/N = 3).L-Trp-rGO@PtNPs with enantiomeric composition of L-and D-DOPA at different concentrations: (a) 2 Â 10 À3 mol L À1 and (b) 5 Â 10 À3 mol L À1 .

Chiral PEDOT-Based Enantioselective Electrode Modification Material for Chiral Electrochemical Sensing: Mechanism and Model of Chiral Recognition

“…Various surface modifications that allow enantioselective electrochemical recognition have been reported, and four types of surface modification materials are commonly used: (a) protein-type molecules, − which recognize chiral molecules by antigen–antibody interactions or receptor–ligand binding; (b) metal complexes, − for which chiral recognition is mostly based on the principle of chiral ligand exchange; (c) carbon-based nanocomposites, such as graphene-supported platinum nanoparticles, hollow carbon microspheres, and single-walled carbon nanotubes; and (d) chiral polymers, − which harness various interactions with analytes, such as oxidation and reduction, protonation and deprotonation, reactions with nucleophilic agents, ion-exchange, adsorption, and complexation. Research on using chiral polymers for enantioselective electrochemical recognition began in 1988 via the electropolymerization of a thiophene monomer that was covalently substituted with chiral substituents at the 3-position.…”

Chiral Graphene Hybrid Materials: Structures, Properties, and Chiral Applications

“…[ 204 ] Different from most of the chiral metal complex catalyst hybrids developed for asymmetric catalysis, Os‐based chiral hybrid was intended for electrochemical sensing, [ 203 ] while the Fe‐based chiral hybrid was intended for microwave absorption. [ 204 ] Some metal complexes were immobilized on graphene in the form of metallic nanoparticles, including Ni nanoparticles, [ 207 ] Pd nanoparticles, [ 208 ] Pt nanoparticles, [ 209 ] and Ru nanoparticles. [ 210 ] Most of the chiral hybrid catalysts were developed for accomplishing asymmetric catalysis.…”

Synthesis and properties of novel ammonium-based room-temperature gemini ionic liquids

“…On the contrary, the viscosity deviations are positive when the mixture is dominated by strong specic interactions (H-bonds). 47 Furthermore, the negative values of Dh for the binary mixtures may also imply that the viscosities of associations formed between unlike molecules are relatively greater than those of the like ones. Negative values of Dh may also occur for the binary mixtures in which dispersion forces are dominant, particularly for the mixtures containing different molecular sizes.…”