Sensitive Electrochemical Detection of Tryptophan Using a Hemin/G-Quadruplex Aptasensor

Abstract

In this study, we design an electrochemical aptasensor with an enzyme-free amplification method to detect tryptophan (Trp). For the amplified electrochemical signal, the screen-printed electrode was modified with dendritic gold nanostructures (DGNs)/magnetic double-charged diazoniabicyclo [2.2.2] octane dichloride silica hybrid (Fe3O4@SiO2/DABCO) to increase the surface area as well as electrical conductivity, and the hemin/G-quadruplex aptamer was immobilized. The presence of Trp improved the catalytic characteristic of hemin/G-quadruplex structure, which resulted in the efficient catalysis of the H2O2 reduction. As the concentration of Trp increased, the intensity of H2O2 reduction signal increased, and Trp was measured in the range of 0.007–200 nM with a detection limit of 0.002 nM. Compared with previous models, our sensor displayed higher detection sensitivity and specificity for Trp. Furthermore, we demonstrated that the proposed aptasensor successfully determined Trp in human serum samples, thereby proving its practical applicability.

An Electrochemical Impedance Spectroscopy-Based Aptasensor for the Determination of SARS-CoV-2-RBD Using a Carbon Nanofiber–Gold Nanocomposite Modified Screen-Printed Electrode

“…The surface coverage of the aptamer (Γ aptamer )on the surface of the electrode was obtained according to the electrostatic interaction between Ru(NH 3 ) 6 3+ as a positively charged redox probe and the negatively charged phosphate backbone of aptamer [39]. The surface coverage of the aptamer (Γ aptamer ) was found to be 52.8 pmol•cm −2 (3.18 × 10 13 molecules•cm −2 ).…”

Review—Recent Trends in Supramolecular Recognition of Dopamine, Tyrosine, and Tryptophan, Using Electrochemical Sensors

“…Also, for the concept of precision medicine the recent developments in electrochemical sensing of L-tryptophan in human serum samples using a hemin/G-quadruplex aptasensor 85 and electrochemical aptamer-based (E-AB) sensors 86 in urine samples were reported.…”

A Review of Sensors and Biosensors Modified with Conducting Polymers and Molecularly Imprinted Polymers Used in Electrochemical Detection of Amino Acids: Phenylalanine, Tyrosine, and Tryptophan

“…From among these methods, mention must be made of the classical high-performance liquid chromatography (HPLC) [1][2][3][4][5], mass spectrometry [6][7][8][9], fluorimetry [10], colorimetry [7,11,12], chemiluminescence [13][14][15], Raman spectroscopy [16,17], UV-Vis spectroscopy [18], capillary electrophoresis [19][20][21], and atomic force spectroscopy [22]. Moreover, versatile methods for detecting AAs have been developed and used: electrochemical ones based on sensors and biosensors, which use cyclic voltammetry (CV) [23][24][25][26][27][28] as a detection method, chronoamperometry (CA) [29], differential pulse voltammetry (DPV) [30][31][32], square wave voltammetry (SWV) [33][34][35], and linear sweep voltammetry (LSV) [36,37].…”