Yucong Li

Bridged β-cyclodextrin-functionalized MWCNT with higher supramolecular recognition capability: The simultaneous electrochemical determination of three phenols

A rapid and sensitive electrochemical sensor based on disulfides bridged β-cyclodextrin dimer-functionalized multi-walled carbon nanotube (DBβ-CD-MWCNT) nanohybrids with higher supramolecular recognition capability was successfully constructed for the first time. Simultaneous trace analysis of three phenols (4-aminophenol, 4-AP; 4-chlorophenol, 4-CP; 4-nitrophenol, 4-NP) in tap-water and wastewater samples was performed based on the constructed sensor. Cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy were utilized to characterize the properties of the modified electrode. The proposed DBβ-CD-MWCNT-modified electrode displayed electrochemical signal superior to those of β-CD-MWCNT and MWCNT towards 4-AP, 4-CP, and 4-NP. Under optimal conditions, differential pulse voltammetry was used to simultaneously quantify 4-AP, 4-CP, and 4-NP within the concentration range of 0.01-20, 0.1-200, and 0.1-200 µM, respectively. The detection limits (S/N=3) of the DBβ-CD-MWCNT nanohybrid electrode for 4-AP, 4-CP, and 4-NP were 0.0042, 0.028, and 0.048 µM, respectively. Satisfactory results revealed that this proposed electrochemical sensor can provide a promising candidate for the simultaneous trace analysis of 4-AP, 4-CP, and 4-NP in environmental monitoring of water and wastewater samples. The present work might broaden the channel toward the application of bridged CD in the electrochemical sensing or biosensing.

A comparison study of macrocyclic hosts functionalized reduced graphene oxide for electrochemical recognition of tadalafil

The present work described the comparison of β-cyclodextrin (β-CD) and p-sulfonated calix[6]arene (SCX6) functionalized reduced graphene oxide (RGO) for recognition of tadalafil. In this study, tadalafil and two macrocycles (β-CD and SCX6) were selected as the guest and host molecules, respectively. The inclusion complexes of β-CD/tadalafil and SCX6/tadalafil were studied by UV spectroscopy and molecular simulation calculations, proving the higher supermolecular recognition capability of SCX6 than β-CD towards tadalafil. The β-CD@RGO and SCX6@RGO composites were prepared by a wet-chemical route. The obtained composites were characterized by Fourier transform infrared spectrometry, thermogravimetric analysis, atomic force microscopy, and zeta potential. The SCX6@RGO showed a higher electrochemical response than β-CD@RGO, which was caused by the higher recognition capability of SCX6 than β-CD. By combining the merits of SCX6 and the RGO, a sensitive electrochemical sensing platform was developed based on the SCX6@RGO nanohybrids. A linear response range of 0.1-50 μM and 50-1000 μM for tadalafil with a low detection limit of 0.045 μM (S/N=3) was obtained by using this method. The constructed sensing platform was successfully used to determine tadalafil in herbal sexual health products and spiked human serum samples, suggesting its promising analytical applications for the trace level determination of tadalafil.

Immunosensor for prostate-specific antigen using Au/Pd@flower-like SnO2 as platform and Au@mesoporous carbon as signal amplification

In the present work, a sandwich-type electrochemical immunosensor for ultrasensitive determination of prostate-specific antigen (PSA) was designed by using Au/Pd@SnO2 as sensing platform and gold@mesoporous carbon nanocomposites (Au@CMK-3) as signal amplification. In this work, Au@CMK-3 was prepared for immobilizing large amounts of redox probe-methylene blue (MB), horseradish peroxidase (HRP), and secondary antibodies (Ab2), leading to the formation of Au@CMK-3–MB–Ab2–HRP bioconjugate. Furthermore, Au/Pd@SnO2 was utilized as the biosensor platform to immobilize the primary antibodies (Ab1) leading a further enhancement in the sensitivity of immunosensor. With the synergistic effects among the Au/Pd@SnO2 platform, the Au@CMK-3 nanocarrier, the ultrafine Pd NPs electrocatalyst, and HRP enzymatic reactions, an almost doubled amplified detection signal was achieved in the presence of H2O2, so as to improve the detection limit of the proposed immunosensor effectively. The constructed immunosensor exhibited desirable performance for determination of PSA with a wide linearity in the range from 0.01 to 100 ng mL−1 and a relatively low detection limit of 3 pg mL−1. The proposed immunosensor was also used to determine PSA in human serum with satisfactory results, implying potential applications in immunoassays.