Dual-Signal Electrochemical Enantiospecific Recognition System via Competitive Supramolecular Host–Guest Interactions: The Case of Phenylalanine

Abstract

For developing highly selective and sensitive electrochemical sensors for chiral recognition, taking advantage of the synthetical properties of β-cyclodextrin (β-CD, strong host−guest recognition) and carbon nanotubes wrapped with reduced graphene oxide (CNTs@rGO, excellent electrochemical property and large surface area), as well as the differences in binding affinity between β-CD and guest molecules, a dual signal electrochemical sensing strategy was proposed herein for the first time in chiral recognition based on the competitive host−guest interaction between probe and chiral isomers with β-CD/CNTs@rGO. As a model system, rhodamine B (RhB) and phenylalanine enantiomers (Dand L-Phe) were introduced as probe and target enantiomers, respectively. Due to the host−guest interactions, RhB can enter into the β-CD cavity, showing remarkable oxidation peak current of RhB. In the presence of L-Phe, competitive interaction with the β-CD cavity occurs and RhB are replaced by L-Phe owing to the stronger binding affinity between L-Phe and β-CD, which results in the peak current of RhB decreasing and the peak current of L-Phe appears, and interestingly, the changes of both signals linearly correlate with the concentration of L-Phe. As for D-Phe, it cannot replace RhB owing to the weaker binding affinity between D-Phe and β-CD. Based on this, a dual-signal electrochemical sensor was developed successfully for recognizing Phe. This dual-signal sensing strategy can provide highly selective and sensitive recognition compared to single-signal sensor and has important potential applications in chiral recognition.C hirality has an important impact on chemical/biological research, since most active substances possess chirality. Generally, the performance of chiral enantiomers show great differences in terms of biochemical activity, toxicity, transport processes, and metabolic pathways. 1−3 Typically, only one isomer exhibits perfect activity and the other has no desirable value and even causes serious side-effects. Thus, chiral recognition is always a popular topic in chemical and biological research. 4−6 For resolving this problem, many approaches, such as capillary electrophoresis, 7 high-performance liquid chromatography, 8 circular dichroism spectroscopy, 9,10 colorimetry 11,12 and fluorescence, 13,14 were developed to recognize electroactive chiral molecules, which are very important in chiral recognition. However, the most of reported approaches need complex sample pretreatment and expensive chiral columns and are time-consuming as well. 15,16 Recently, electrochemical chiral recognition has received considerable attention, due to the many advantages they offer, such as low cost, fast response, inexpensive instrument, and facile miniaturization. 17−22 For instance, Kong et al. 23

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

“…The above preparation strategy offers a versatile platform for designing and developing chiral nanohybrids derived from graphene, cyclodextrins, and stimuli‐responsive polymer chains. [ 105 ] Aside from graphene and cyclodextrin, other material also can be combined with the hybrid for developing advanced functional architectures with multicomponents, hierarchical structures, and excellent comprehensive properties, e.g., chiral hybrids constructed by carbon nanotube, RGO, and β ‐CD toward electrochemically recognition of phenylalanine enantiomers; [ 106 ] electrochemical sensors containing 3D graphene layers and hydroxypropyl‐ β ‐cyclodextrin units for recognition of tryptophan enantiomers. [ 107 ] In particular noticeably, the existence of magnetic nanoparticles facilitates the chiral hybrids to be easily restored for further recycling use.…”

“…for instance, magnetic particles providing magneticity; [ 102,105 ] and rhodamine B rendering fluorescence for the hybrid chiral materials. [ 106 ] Following the design and preparation strategy, more other building blocks may be utilized to provide their functions. For example, chiral pH‐responsive polymers, [ 115,116 ] chiral temperature‐sensitive polymers, [ 117,118 ] and chiral dynamic covalent structures (e.g., Schiff base [ 119 ] and borate structures [ 120 ] ) can be combined with chiral graphene hybrids to enable them to show stimuli‐responsivity.…”

“…The chirality for creating graphene‐based chiral detectors can be derived from amino acids [ 42,54,60 ] and cyclodextrins. [ 82–86,97,98,105–107 ] Kwak and co‐workers took l ‐phenylalanine as chiral source and synthesized a chiral‐functionalized pyrene material (Boc‐ l ‐Phe‐Pyrene). It was utilized as UV–vis and fluorescent probes for enantioselective sensing.…”

“…This distinctive property also makes cyclodextrins appealing for chiral applications. Up to date, α ‐CD, [ 83 ] β ‐CD, [ 84–86,97,98,100,101,105–107 ] and γ ‐CD [ 108 ] have been intensively employed for chiral functionalization of graphene and its derivatives. Among the three types of cyclodextrins, β ‐CD shows the most extensive applicability as its cavity is well matched with common small chiral molecules.…”

Sandwich-type electrochemical immunosensing of Hypopharyngeal carcinoma biomarker carcinoembryonic antigen based on N-doped hollow mesoporous nanocarbon spheres/gold hybrids as sensing platform and gold/ferrocene as signal amplifier

“…Among these methods, the electrochemical method coupled with sandwich-type immunosensors especially attracted considerable attentions owing to its unique advantages in signal amplification ability and sensitivity as well as speed. 14 For instance, Ghahremaniet al 15 prepared gold and silver hybrids to construct sandwich-type electrochemical immunosensor of CEA. In this work, silver nanoparticles/streptavidin/horseradish peroxidase was used as signaling amplifiers and probe, hydroquinone and hydrogen peroxide were added to the electrolyte.…”