Urchin-Like Chiral Metal–Organic Framework/Reduced Graphene Oxide Nanocomposite for Enantioselective Discrimination of d/l-Tryptophan

Abstract

An urchin-like chiral metal–organic framework/reduced graphene oxide (urchin-CMOF/rGO) nanocomposite was developed as the electrochemical sensing interface for robust, efficient, and high-selective discrimination of tryptophan (Trp) enantiomers. An urchin-CMOF/rGO nanocomposite was elaborately integrated to combine the amplification of electrical conduction by rGO and the enantioselectivity by asymmetric CMOF. On the basis of this novel nanocomposite-mediated sensor, chiral recognition of d/l-Trp was successfully achieved by the differential potential ratiometric method. Different percentages of Trp racemic mixtures were determined in a good linear relationship with specific peak potentials, which effectively detours the nonspecific signal of concomitant interference from most current-based voltammetries. Even in the complex human cerebrospinal fluid, the simulative ratiometric results of Trp-spiked samples were accurately detected with low false negatives. Additionally, diverse CMOF-regulated hybrid materials have great potential for chiral recognition in pharmaceutical monitoring and biochemical analysis.

Zirconium Metal Organic Framework-Based Hybrid Sensors with Chiral and Luminescent Centers Fabricated by Postsynthetic Modification for the Detection and Recognition of Tryptophan Enantiomers

“…Therefore, there is an urgent need to develop a reliable method for the identification and detection of amino acid enantiomers, which is of great significance for the research in the field of biology or chemistry. In recent years, many detection methods of enantiomers have been reported, such as electrochemical sensing, ,, circular dichroism, , high-performance liquid chromatography, , NMR analysis, , and so forth. However, these analysis methods require complex operation, expensive instruments, and high detection cost and do not have universality.…”

Chiral voltammetric sensor for tryptophan enantiomers by using a self‐assembled multiwalled carbon nanotubes/polyaniline/sodium alginate composite

“…Alternatively, the electrochemical measurement is of significance due to the advantages of fast detection, low prices, high sensitivity, and anti‐jamming property 6–8 . Many scholars made great effort on the investigation of chiral selectors used for the fabrication of electrochemical sensing interface, such as chiral carbon dots, amino acid, chiral supramolecules, and MOFs 9–12 . In some cases, only modifying the chiral selectors on the electrode will hinder electronic transmission of chiral interface, weakening chiral recognition signal.…”

Highly Efficient versus Null Electrochemical Enantioselective Recognition Controlled by Achiral Colinkers in Homochiral Metal–Organic Frameworks

“…Such a high enantioselective recognition efficiency is rare in electrochemical sensing. Previous electrodes for chiral discrimination of Trp have been fabricated by modification with chiral peptides, , organosilica, carbohydrates, − conducting polymers, − metal complexes, ,, and a ZIF-type MOF doped with d -histidine . The peak current ratios for Trp isomers fall in the range of 2–14 (Table S5).…”

“…The chirality has allowed remarkable performances of MOFs in asymmetric catalysis, enantioselective sorption and separation, and other applications. − However, the studies using chiral MOFs for electrochemical sensors have been rather limited. Only several chiral MOFs, assembled from pure chiral linkers or mixed chiral/achiral linkers or obtained by post-synthetic chiral modification, have been demonstrated to be effective electrode modifiers, allowing enantiomeric recognition of some chiral substrates (e.g., [Cu 2 (cam) 2 dabco] n , [Cu 4 L 4 ] n (L = N -(2-hydroxybenzyl)- l -leucine), urchin-CMOF/rGO, l -Glu/MIL-125­(Ti)/TiNM, TiO 2 /MIL-125-NH- l -His, and [Ag­(s,r-L)]­(PF 6 )·3C 4 H 8 O 2 ·0.5H 2 O). − However, the recognition selectivity is still low. It is a great scientific challenge to construct a chiral microenvironment for efficient enantioselective molecular recognition, and even more challenging is to find the way for efficient translation of the recognition to an electrochemical response.…”