Chiral Detection of Glucose: An Amino Acid-Assisted Surface-Enhanced Raman Scattering Strategy Showing Opposite Enantiomeric Effects on SERS Signals

Abstract

It is of considerable concern to establish chiral detection methods for revealing enantioselective interactions among chiral molecules. Surfaceenhanced Raman scattering (SERS) spectroscopy is sensitive to molecular interaction due to bond variations. However, its application in chiral detection is underexplored. Inspired by the chiral selectivity toward glucose and amino acids in life, we herein propose a SERS strategy based on molecular interactions for the discrimination of D-and L-glucose (Glu) using chiral phenylalanine (Phe) decorated on gold nanoparticles as a chirality selector and Raman reporter. Interestingly, the SERS signal of L-Phe is enhanced by D-Glu but suppressed by L-Glu. In contrast, the SERS signal of D-Phe is increased by L-Glu but decreased by D-Glu. According to the above-observed intensity change (ΔI) of the SERS signal of Phe induced by Glu, it is easy to determine the chiral configurations (judged by the positive or negative sign of ΔI), enantiomeric excess (ee) values, and concentrations (estimated by the magnitude of ΔI) of Glu. Taking advantage of the high SERS enhancement and opposite enantiomeric effects on SERS signals, the proposed strategy enables enantiomeric discrimination at a low Glu concentration (10 −6 mol/L) and is further exerted for the noninvasive detection of D-/L-Glu in saliva samples. In contrast, the common chiroptical analysis tool of circular dichroism (CD) spectroscopy failed to directly detect Glu enantiomers.

19F NMR enantiodiscrimination and diastereomeric purity determination of amino acids, dipeptides, and amines

“…Chiral amino-group compounds are not only important biomolecules but also chemical and pharmaceutical intermediates for the synthesis of bioactive compounds. Currently, various methods have been widely used for the elucidation of absolute configuration and enantiomeric excess (ee), including NMR, [1][2][3][4][5][6][7][8][9][10][11][12] circular dichroism, [13][14][15][16][17] fluorescence, 18 SERS, 19 chromatography, 20,21 ion mobility mass spectrometry, 22 and electrochemistry. 23,24 However, optical spectroscopic techniques require pure enantiomers that are obtained by isolating each enantiomeric pair or by extracting each enantiomer from its original matrix prior to analysis.…”

“…23,24 However, optical spectroscopic techniques require pure enantiomers that are obtained by isolating each enantiomeric pair or by extracting each enantiomer from its original matrix prior to analysis. For NMR methods, 1 H and 19 F NMR are commonly utilized in enantiospecific analysis relying on the discriminative resonance signals of the diastereoisomers generated by CSA or CDA. Despite their high sensitivity, the use of NMR active 1 H nuclei in complex samples has been limited due to a narrow chemical shift range (∼14 ppm) and the potential for signal overlap.…”

Enantiomeric discrimination by chiral electromagnetic resonance enhancement

“…More special articles will be found in this issue as well as in those to come.] aqueous solutions, such as glucose in saliva 7 and dyes in pond water. 8 In solid sensing applications, CEMR enhancement has been used to detect chiral molecules in materials, such as polymers 9 and pharmaceuticals.…”

“…CEMR enhancement has been applied to a variety of different sensing applications, 3 such as the detection of amino acid films, 4 amyloid proteins, 5 and spontaneous chiral aggregates 6 . In solution‐phase sensing applications, CEMR enhancement has been used to detect chiral molecules in aqueous solutions, such as glucose in saliva 7 and dyes in pond water 8 . In solid sensing applications, CEMR enhancement has been used to detect chiral molecules in materials, such as polymers 9 and pharmaceuticals 10 …”

Chiral-Controlled Cyclic Chemiluminescence Reactions for the Analysis of Enantiomer Amino Acids

“…The enantiomeric recognition could be controlled by the electron spin orientations based on achiral magnetic substrates, and the rich host–guest chemistry. The rich host–guest chemistry promises the most concerned enantiomeric recognition processes. , For example, 3D covalent organic frameworks were utilized to separate racemic alcohols; chiral plasmonic gold nanoparticles were employed to sense biomolecules; homochiral zirconium metal–organic cages were used to recognize chiral AAs; and 2D porous nanosheets of the chiral metal–organic framework (MOF) were raised to recognize vapor enantiomers . The stable architectures, permanent porosity, and versatile signal transductions have made MOF ideal candidates for fabricating advanced sensors. , Chiral MOF has demonstrated great potential in enantioselective applications …”