Tryptophan Enantiomers Research Articles

Chemical properties of inner and surficial regions of hydrogen-bonded clusters of biological molecules: ultraviolet photodissociation and water adsorption analyses in the gas phase.

The chemical and physical properties of cold, gas-phase hydrogen-bonded clusters of L-alanine (L-Ala), L-trialanine (L-Ala3), L-tetraalanine (L-Ala4), and tryptophan (Trp) enantiomers were investigated using tandem mass spectrometry with an electrospray ionization source and cold ion trap. From the ultraviolet (UV) photodissociation spectra at 265-290nm, the electronic structures of homochiral H+(L-Trp)(L-Ala) at 8K were found to be different from those of heterochiral H+(D-Trp)(L-Ala) and protonated Trp. The number of water molecules adsorbed on the surface of gas-phase H+(D-Trp)(L-Ala) was larger than that of H+(L-Trp)(L-Ala), indicating stronger intermolecular interactions of L-Ala with H+(L-Trp) than those with H+(D-Trp). The product ion spectrum obtained by 265nm photoexcitation of H+(L-Trp)(L-Ala3)(H2O)n formed via gas-phase water adsorption on H+(L-Trp)(L-Ala3) showed that the evaporation of water molecules was the main photodissociation process. In the case of H+(L-Trp)(L-Ala4)(H2O)n, signals of H+(L-Ala4) (H2O)n formed via L-Trp evaporation were observed in the product ion spectra, and the cross-section for UV photoinduced L-Trp evaporation became larger as the number of adsorbed water molecules increased. This observation indicates that water molecules were selectively adsorbed on the H+(L-Ala4) side of H+(L-Trp)(L-Ala4) and weakened the intermolecular interactions between L-Trp and H+(L-Ala4) in the hydrogen-bonded cluster.

Combination of an aptamer-based immunochromatography assay with nanocomposite-modified screen-printed electrodes for discrimination and simultaneous determination of tryptophan enantiomers

While the detection of tryptophan enantiomers is of great importance in the field of pharmacy and biotechnology, significant limitations exist in their selective determination using conventional methods. A simple solution is to use immunochromatographic assays, thereby separating enantiomers and detecting them by electrochemical methods. In this study, the l-tryptophan enantiomer is captured by biotin-aptamer immobilized on an immunochromatographic test strip and recognized using a screen-printed electrode. PdCuCo/RGO nanocomposite is coated on the electrode surface in order to amplify the sensor sensitivity. The electrochemical measurements are performed by differential pulse voltammetry. At the optimal conditions, the sensor response shows a good linear relationship with the tryptophan concentration in the range of 0.08–20.0 μM, providing a detection limit of 0.03 μM. Since the sensor is stable and not susceptible to interfering species, it is possible to employ it as a reliable tool for the determination of the tryptophan level in biological samples and the diagnosis of a specified disease.

Construction of CS/BSA multilayers for electrochemical recognition of tryptophan enantiomers

• A chiral interface based on chitosan (CS) and bovine serum albumin (BSA) was fabricated by simple self-assembly technique. • The chiral recognition of Trp enantiomers at (CS/BSA) 1.5 /GCE was demonstrated by DPV and contact angle measurements. • The percentage of L-Trp or D-Trp in a non-racemic mixture solution can be accurately predicted by (CS/BSA) 1.5 /GCE chiral interface. Ultra stable and reproducible electrochemical chiral interface ((CS/BSA) 1.5 /GCE) based on chitosan (CS) and bovine serum albumin (BSA) was fabricated using layer-by-layer (LbL) self-assembly technique. Its structure and properties were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and electrochemical methods. Snowflake like morphology was observed on the (CS/BSA) 1.5 films using SEM. Interestingly, the (CS/BSA) 1.5 chiral interface achieved chiral recognition of D-Trp and L-Trp via contact angle measurements. Under optimized experimental conditions, differential pulse voltammetry (DPV) results showed that the peak current ratio of D-Trp to L-Trp (I D /I L ) was 3.83 at (CS/BSA) 1.5 /GCE (glass carbon electrode). In addition, there was a good linear relationship between the peak current and Trp enantiomer concentration in the range of 0.005–0.15 mM. Our study shows the (CS/BSA) 1.5 /GCE can be used to quickly determine the ratio of enantiomers in non-racemic Trp mixture solutions, which is of great significance for the chiral recognition in non-racemic mixtures of chiral compounds.

Aβ Protein Detector Based on AAO Confined Self-Assembly System

With the advent of the aging of the world’s population, the number of patients suffering from Alzheimer’s disease (AD) is increasing year by year, and how to diagnose early and treat AD has become a problem for the world. After decades of hard work, people have made a series of breakthroughs in the pathogenesis of AD. One of the most widely accepted is that there is a large amount of amyloid-[Formula: see text] protein deposition in the body of AD patients. This also provides us with a new idea for early diagnosis of AD. In this paper, a confined self-assembly system based on AAO/ZnS is constructed to specifically respond to amyloid-[Formula: see text] protein. The obtained samples were characterized by FESEM, XPS and UV–Vis. This system specifically recognizes A[Formula: see text] protein by modifying the tryptophan enantiomers. The experimental results show that the samples synthesized under the self-assembly system of modified D-Trp have higher response sensitivity to amyloid-[Formula: see text] protein. This provides a new idea for the self-assembly system based on the limited space of the nano-biomimetic channel in biological detection, and also shows great potential in improving the sensitivity of the biodetector.

Common materials, extraordinary behavior: An ultrasensitive and enantioselective strategy for D-Tryptophan recognition based on electrochemical Au@p-L-cysteine chiral interface

The poly-L-cysteine modified Au nanoparticles (Au@p-L-Cys) were constructed on electrode surface as a highly efficient chiral interface for tryptophan (Trp) enantiomers recognition via one step electropolymerization. With the aid of Cu2+, L-Cys residues and D-Trp target formed a sandwich complex D-Trp-Cu2+-L-Cys, while L-Trp was unable to form such complex due to the steric hindrance provided by the chiral interface, which was confirmed by the electrochemical and SEM results. With the introduction of ferricyanide probe, D-Trp produced significant current decrease while L-Trp produced a slight current increase, which implied the successful enantioselective recognition of Trp enantiomers (specifically D-Trp) in the true sense. This novel sensor showed a surprisingly wide linear range toward D-Trp of 6 × 10−7 M to 1 × 10−2 M, with a detection limit as low as 75 nM (S/N = 3). Moreover, the exclusive enantioselectivity toward D-Trp was discovered since other amino acids showed negligible interference to detection of D-Trp. The recovery of D-Trp in human serum was between 91.30 and 109.3%, which further verified the satisfying specificity and practicality of the proposed strategy. The coordination thermodynamics by UV–Vis spectroscopy and DFT simulation were also used to investigate the enantioselective mechanism. These results highlight the great potential of using Au@p-L-Cys to construct chiral interface for enantiomers recognition and hold the promise of practical application of electrochemical chiral sensors in fields like pharmaceutics and bioanalysis.

Using cellulose, starch and β-cyclodextrin poly/oligosaccharides as chiral inducers for preparing chiral particles

Poly/oligosaccharides are renewable natural resources with abundant chirality. Herein, we develop a general route to prepare optically active particles by using poly/oligosaccharides as both chiral inducers and growth templates. By complexing with Cu(NH3)42+ ions, OH groups on C2 and C3 in poly/oligosaccharides can transfer the chirality to Cu(II) and retain it in CuO. At the same time, poly/oligosaccharides direct growth of CuO by in situ transformation of Cu(NH3)42+ ions. Cellulose nanocrystal (CNC) and starch (ST) are used as representative polysaccharides, and β-cyclodextrin (β-CD) as a representative oligosaccharide, thus dandelion, duchesnea, and chrysanthemum-like composite particles with chiroptical activity are obtained. Besides, chiral CuO/poly(oligo)saccharide particles (CSP) demonstrate enantioselective ability by differentiating coordination with tryptophan (Trp) enantiomers and form Cu-Trp metal organic framework architectures with different morphologies. The study provides an easily accessible approach to prepare novel functional materials by poly/oligosaccharide-based chiral induction and hold great promise in chiral applications.

Off-line two-dimensional LC-MS/MS determination of tryptophan enantiomers in mammalian urine and alteration of their amounts in d-amino acid oxidase deficient mice

D-Tryptophan (D-Trp) is one of the minor D-enantiomers of amino acids discovered in microbes and mollusca. In the present study, a highly-selective 2D chiral LC-MS/MS method has been designed and developed focusing on the determination of Trp enantiomers to investigate the presence and regulation of free D-Trp in mammals. The developed system consisted of a reversed-phase separation for the first dimension, an enantioselective separation for the second dimension and also the detection using a triple quadrupole mass spectrometer for the third/fourth dimensions. Using the present method, urinary D-Trp in mammals, including healthy human volunteers and mice, were successfully determined. Although only l-Trp was observed in a mixed urine sample of healthy volunteers, small amounts of D-Trp were detected in the C57BL/6J mice (n = 5, %D=6.18 ± 0.47). In B6DAO- mice lacking the activity of d-amino acid oxidase (DAO), relatively high levels of D-Trp were observed (n = 6, %d=27.43 ± 3.26). The obtained %d values of Trp in the urine of the C57BL/6J mice and B6DAO- mice were confirmed using various enantioselective columns having different separation properties. These results indicate that the urinary D-Trp level is regulated by DAO in mammals, and further investigations, such as tissue distribution and physiological significance of the intrinsic D-Trp, are expected.

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

By immobilizing the chiral center l-histidine (l-His) into a Zr-based metal-organic framework (MOF) through post-synthetic ligand exchange, a chiral compound MOF-His has been prepared. On this basis, MOF-His is hybridized with Eu3+ ions to obtain the final responsive compound Eu@MOF-His. It is worth noting that the bifunctional material exhibits enantioselective luminescence properties for tryptophan enantiomers. The experimental results demonstrate that tryptophan enantiomers can effectively quench the red-light emission of Eu3+ ions, and also, the quenching rates are various, which may originate from the differences in the interaction between analytes and chiral recognition sites. In addition, Eu@MOF-His can realize the sensing of tryptophan enantiomers in serum. Concurrently, the compound possesses reusability, high sensitivity, and fast response speed, which means that it has the potential to serve as an excellent fluorescent sensor for detecting and identifying tryptophan enantiomers.

An electrochemical chiral sensor based on glutamic acid functionalized graphene-gold nanocomposites for chiral recognition of tryptophan enantiomers

• Glu functionalized RGO-Au nanocomposites were synthesized as an electrochemical chiral sensor. • The electrochemical chiral sensor has high chiral recognition capability for Trp enantiomers. • Mechanism and binding thermodynamics were explained by UV–vis and DFT in detail. A novel chiral sensing platform via the glutamic acid (Glu) functionalized graphene-gold nanoparticles (RGO-Au/ l -Glu and RGO-Au/ d -Glu) synthesized via the one-step hydrothermal method is described for the enantioselective recognition of L- and d -tryptophan (Trp). The SEM, TEM, EDS, AFM, FTIR, and XRD characterization techniques showed that RGO-Au/ l -Glu and RGO-Au/ d -Glu chiral composite were successfully synthesized. By combining the chiral features of Glu and the excellent electrochemical behaviors of RGO-Au, two electrochemical chiral sensing interfaces constructed by RGO-Au/ l -Glu and RGO-Au/ d -Glu modified glassy carbon electrode (GCE) were constructed for electrochemical chiral recognition of Trp enantiomers. The results demonstrated that the RGO-Au/ l -Glu/GCE showed the highest chiral recognition efficiency, the enantioselectivity coefficient (I L /I D ) was 2.56. UV–vis absorption spectroscopy and density functional theory (DFT) calculations proved that RGO-Au/ l -Glu had a strong binding ability with l -Trp. In addition, the chiral sensing interface had a linear response in the 1 mM to 5 mM Trp concentration range and a 0.28 mM detection limit (at S/N = 3) for l -Trp, and 0.86 mM to d -Trp, also had good stability and reproducibility, which can be used as an efficient chiral sensing interface for the recognition of Trp enantiomers.

Stereoselectivity of Interaction of Nonsteroidal Anti-Inflammatory Drug S-Ketoprofen with L/D-Tryptophan in Phospholipid Membranes.

The mechanisms of stereoselectivity of the interaction of chiral drugs with active sites of enzymes and cell receptors attract significant attention. The first reason is the difference in therapeutic activity of the enantiomers of the common drugs. Another reason is the interest in the role of chiral inversion of amino acids involved in various peptides in the development of many diseases including Alzheimer’s, Parkinson’s, type II diabetes, and a number of other pathological conditions. In our study we use elementary chemical process—electron transfer (ET) to simulate individual stages of ligand–receptor and enzyme–substrate interactions. In particular, previous studies of photoinduced ET in chiral donor-acceptor dyads consisting of the nonsteroidal anti-inflammatory drug (R/S)-ketoprofen and (L)-tryptophan show the stereo and spin selectivity of ET in diastereomers. The present study is devoted to the interaction of (S)-ketoprofen with L- and D-enantiomers of tryptophan in homogeneous aqueous solution and in phospholipid membranes. The study was done using the NMR technique and molecular modeling. These approaches confirm efficient penetration of ketoprofen into the lipid bilayer and binding with tryptophan molecule. The short-lived paramagnetic intermediates formed during the photoinduced ET from electron donor tryptophan to ketoprofen have been detected using the chemically induced dynamic nuclear polarization (CIDNP) technique. It was found that S-ketoprofen interacts stereoselectively with tryptophan enantiomers in the lipid membrane. The formation of the ketyl radical of ketoprofen under irradiation leads to the oxidation of membrane lipids and may be the cause of ketoprofen phototoxicity. However, in contrast to a homogeneous solution in phosphate buffer saline, where the amino acid tryptophan accelerates the photodecomposition of KP due to intramolecular hydrogen transfer, tryptophan in a lipid membrane significantly reduces the rate of photodegradation due to a reversible electron (or hydrogen) transfer reaction. The stereoselectivity in the rate of KP and lipids decomposition under UV irradiation of S-ketoprofen in the presence of tryptophan enantiomers in lipid bilayer has been detected.

The hybrids of perylene tetracarboxylic acid functionalized multi-walled carbon nanotubes and chitosan for electrochemical chiral sensing of tryptophan enantiomers

To introduce abundant carboxyl (COOH) groups to the surface of multi-walled carbon nanotubes (MWCNTs) while maintaining the pristine structure of MWCNTs, 3,4,9,10-perylene tetracarboxylic acid (PTCA) was non-covalently grafted to the sidewalls of MWCNTs. The obtained PTCA functionalized MWCNTs (MWCNTs–PTCA) functioned as a scaffold for the further introduction of chitosan (CS) via electrostatic attractions and hydrogen-bonds. The resultant CS/MWCNTs–PTCA could be used for electrochemical chiral sensing of tryptophan (Trp) enantiomers due to the intrinsic chirality of CS and the high electrocatalytic activity of MWCNTs. Under optimized conditions, the Trp enantiomers could be effectively discriminated at the CS/MWCNTs–PTCA modified electrode by differential pulse voltammetry (DPV), demonstrating that the developed CS/MWCNTs–PTCA might be a potential candidate for the construction of electrochemical chiral sensors.

Fabrication of PVDF-blended ultrafiltration membranes incorporated by chiral mesoporous silica for enantioseparation

Novel poly(vinylidene fluoride) (PVDF) ultrafiltration membranes blending with chiral mesoporous SiO2 materials were constructed to improve the anti-fouling and separation performance of PVDF-blended membranes. The formation of asymmetric mesoporous structure of chiral mesoporous SiO2 caused their large hydrophilic surface and significant chiral features, which enhanced the hydrophilicity and polarity of the resulting PVDF membranes blended with chiral mesoporous SiO2. So, the PVDF-blended membranes containing chiral mesoporous SiO2 had a high permeation performance and anti-fouling property. After blending with chiral mesoporous SiO2, the maximum flux of membranes exceeded 500 L·m−2·h−1 and was 6.5-fold higher than that of neat PVDF. Due to the stereo-specific interaction between enantiomers and chiral recognition sites introduced by chiral mesoporous SiO2 in the membranes, all PVDF-blended membranes had evident enantioseparation performance for DL-racemic tryptophan. The C-SiO2-20/PVDF-blended membranes had the highest enantioseparation performance under the same addition content and the maximum enantiomeric excess (e.e.%) was more than 20 %. Given the strong stereo-specific interaction and hydrogen bonding between d-tryptophan and β-cyclodextrin (β-CD), the addition of more β-CD would introduce more chiral recognition sites into the membranes, thereby enhancing the enantioseparation performance of the membranes for d-tryptophan. The maximum e.e.% of C-SiO2-20/β-CD/PVDF-blended membranes for the tryptophan enantiomer reached 55%.

Self‐Propelled Multifunctional Microrobots Harboring Chiral Supramolecular Selectors for “Enantiorecogniton‐on‐the‐Fly”

AbstractHerein, a general procedure for the synthesis of multifunctional MRs, which simultaneously exhibit i) chiral, ii) magnetic, and iii) fluorescent properties in combination with iv) self‐propulsion, is reported. Self‐propelled Ni@Pt superparamagnetic microrockets have been functionalized with fluorescent CdS quantum dots carrying a chiral host biomolecule as β‐cyclodextrin (β‐CD). The “on‐the‐fly” chiral recognition potential of MRs has been interrogated by taking advantage of the β‐CD affinity to supramolecularly accommodate different chiral biomolecules (i.e., amino acids). As a proof‐of‐concept, tryptophan enantiomers have been discriminated with a dual‐mode (optical and electrochemical) readout. This approach paves the way to devise intelligent cargo micromachines with “built‐in” chiral supramolecular recognition capabilities to elucidate the concept of “enantiorecognition‐on‐the‐fly”, which might be facilely customized by tailoring the supramolecular host–guest encapsulation.

Self-Propelled Multifunctional Microrobots Harboring Chiral Supramolecular Selectors for "Enantiorecognition-on-the-Fly".

Herein, a general procedure for the synthesis of multifunctional MRs, which simultaneously exhibit i) chiral, ii) magnetic, and iii) fluorescent properties in combination with iv) self‐propulsion, is reported. Self‐propelled Ni@Pt superparamagnetic microrockets have been functionalized with fluorescent CdS quantum dots carrying a chiral host biomolecule as β‐cyclodextrin (β‐CD). The “on‐the‐fly” chiral recognition potential of MRs has been interrogated by taking advantage of the β‐CD affinity to supramolecularly accommodate different chiral biomolecules (i.e., amino acids). As a proof‐of‐concept, tryptophan enantiomers have been discriminated with a dual‐mode (optical and electrochemical) readout. This approach paves the way to devise intelligent cargo micromachines with “built‐in” chiral supramolecular recognition capabilities to elucidate the concept of “enantiorecognition‐on‐the‐fly”, which might be facilely customized by tailoring the supramolecular host–guest encapsulation.

(Co-)amorphization of enantiomers – Investigation of the amorphization process, the physical stability and the dissolution behavior

A novel approach for improvement of the aqueous solubility of poorly water soluble compounds applying co-amorphous systems was investigated by application of the enantiomers of the chiral amino acid tryptophan (TRP) as the model system. (Co-)amorphization of various forms of crystalline TRP was achieved by ball milling. Solid state analysis demonstrated significant differences in the amorphization tendency and physical stability between the two TRP enantiomers alone, the TRP racemate and an equimolar physical mixture of D- and L-TRP (TRP conglomerate). Ball milling for 6 h was required to obtain fully amorphous plain D- and L-TRP, whereas the TRP racemate and the TRP conglomerate were transformed into their amorphous forms already within 90 and 60 min of ball milling, respectively. Physical stability of the co-amorphous TRP conglomerate was observed for up to 60 d at ambient conditions as well as 40 °C/0 % RH. In contrast, the amorphous TRP racemate showed a reduced physical stability under ambient conditions. Interestingly, the intrinsic dissolution rates of the amorphous TRP conglomerate and racemate were not higher than those of the respective crystalline forms. In conclusion, applying two enantiomers of a chiral compound may be a promising approach for fast amorphization of an API and for improving the physical stability of the resulting amorphous form.

Chiral recognition of tryptophan enantiomers with UV–Vis spectrophotometry approach by using L-cysteine modified ZnFe2O4 nanoparticles in the presence of Cu2+

Amino acids play a very important role in the fields of pharmacy and biochemistry, and the identification of amino acid enantiomers has become a research hotspot. In this study, chiral nanomaterials ZnFe2O4-L-Cys (Cys = cysteine) were prepared by the mechanical stirring method and characterizad by different kinds of techniques. The effect of pH and Cu2+ on the recognition of tryptophan by chiral nanomaterials ZnFe2O4-L-Cys was further explored by ultraviolet–visible spectroscopy. The experimental results show that when the pH of the recognition environment is neutral, ZnFe2O4-L-Cys can be used as chiral selectors for tryptophan enantiomers in the presence of Cu2+ and the absorbance of L-Trp is always stronger than D-Trp within a certain concentration range, which provides a novel and convenient way for the chiral recognition of tryptophan enantiomers.

Drop-coated molybdenum disulfide-ionic liquid for improving the electrochemical chiral recognition ability of chitosan

A faithful and facile strategy to significantly improve the electrochemical chiral recognition ability of chitosan is proposed via drop-coating molybdenum disulfide-ionic liquid (MoS 2 -IL) nanocomposite. • MoS 2 -IL was first used to improve the enantiorecognition ability of CS. • There is a good linear relationship between the DPV peak potential and ee. • The proposed sensor exhibited satisfactory reproducibility and stability. • The proposed sensor exhibited enantiorecognition ability for other enantiomers. A faithful strategy to significantly improve the enantiorecognition ability of chitosan (CS) is proposed via drop-coating molybdenum disulfide (MoS 2 )-ionic liquid (IL) nanocomposite. The present work describes a novel, simple, and effective chiral interface based on MoS 2 -IL/CS nanocomposite which was elaborately integrated to combine the electrical signal amplification and space complexity of MoS 2 -IL and vast enantiorecognition sites of CS for the electrochemical enantiorecognition of tryptophan (Trp) enantiomers. Differential pulse voltammetry (DPV) was adopted to evaluate the potential differences (ΔE P ) between the oxidation peaks of l -Trp and d -Trp. MoS 2 -IL/CS nanocomposite showed higher chiral recognition ability result from spatial asymmetry of MoS 2 -IL/CS. Herein, several parameters, such as drop-coated volume and concentration of MoS 2 -IL, electrodeposited viscosity, time and temperature of CS, detection temperature and pH were optimized in order to obtain a large ΔE P signal between l -Trp and d -Trp, and the ΔE P value can reach 53.3 mV under optimal conditions. Furthermore, different percentages of Trp mixtures and DPV peaks potential were detected with a good linear relationship even in the real sample, which indicated that MoS 2 -IL/CS chiral interface could effectively quantify the enantiomer excess (ee) of Trp enantiomers in Trp mixtures.

Construction of Cs/Bsa Multilayers for Electrochemical Recognition of Tryptophan Enantiomers

Construction of Cs/Bsa Multilayers for Electrochemical Recognition of Tryptophan Enantiomers

A facile electrochemical chiral sensor for tryptophan enantiomers based on multiwalled carbon nanotube/hydroxypropyl-β-cyclodextrin functionalized carboxymethyl cellulose

The development of facile and convenient sensors for the chiral recognition of enantiomers is of great significance for medical and life science. Herein, a sensitive electrochemical sensor for the chiral recognition of tryptophan (Trp) enantiomers was developed based on the assembly of cellulose grafted with hydroxypropyl-β-cyclodextrins (CMC-CD), multi-walled carbon nanotubes (MWCNTs) and copper ions on the surface of a GCE. The morphologies and electrochemical behaviors of the prepared electrode (GCE/MWCNTs/CMC-CD-Cu) were characterized by differential pulse voltammetry (DPV), FT-IR, XPS, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The oxidation peak current ratio (IL/ID) of DPV could be reached at 2.2 under the optimal experimental conditions. Compared with D-Trp, the higher electrochemical signal of L-Trp was ascribed to the stronger affinity for L-type tryptophan. Additionally, the as-prepared chiral sensor was successfully utilized to analyze the amount of D-Trp in the racemic mixture.

Electrochemical chiral recognition of tryptophan enantiomers based on copper-modified β-cyclodextrin

An electrochemical chiral sensing platform was fabricated by successive modification of Au@Pt bimetallic nanoparticles, poly(cysteine), and Cu 2 -β-CD on the surface of glassy carbon electrode. Good conductivity and high surface area of Au@Pt endowed the sensor with high sensitivity. Cu 2 -β-CD enabled the sensor to effectively identify tryptophan (Trp) enantiomers upon the host–guest interaction with a high the oxidation peak current ratio (I L /I D ) of 2.38. Thus, the simple and efficient sensor can be used for the discrimination of Trp enantiomers. • Cu 2 -β-CD can discriminate Trp enantiomers based on the host–guest interaction. • Au@Pt bimetallic nanoparticles improved the sensitivity of the sensor. • Sensor showed excellent enantioselectivity toward Trp enantiomers. • Facile preparation facilitates the present approach promising. A novel electrochemical chiral sensor was constructed for the discrimination of Tryptophan (Trp) by the modification of Au@Pt bimetallic nanoparticles, poly(cysteine) (PL-Cys), and Cu 2+ -modified β-cyclodextrin (Cu 2 -β-CD) on the surface of glassy carbon electrode. The constructed sensor was characterized by transmission electron microscopy, infrared spectroscopy, UV–vis adsorption spectra, and the electrochemical experiments. The modified Au@Pt endowed the sensor with high surface area and good conductivity. The electropolymerized PL-Cys facilitated the loading of Cu 2 -β-CD based on the electrostatic interaction. As a chiral selector, Cu 2 -β-CD enabled the sensor to effectively identify the Trp enantiomers based on the host–guest interaction with a high the oxidation peak current ratio (I L /I D, I L and I D were the oxidation peak currents of l -Trp and d -Trp measured on the sensor, respectively) of 2.38. Under the optimized conditions, I L /I D increased with the increase of l -Trp in the raceme solution, which was further employed for the detection of Trp in serum samples with satisfactory results. With the good selectivity, stability, and reproducibility, the present electrochemical sensor can be used for the simple, rapid, and efficient chiral recognition and real samples determination.