A Dual-Signaling Electrochemical Aptasensor Based on an In-Plane Gold Nanoparticles-Black Phosphorus Heterostructure for the Sensitive Detection of Patulin.

Patulin (PAT), a type of mycotoxin existing in foodstuffs, is harmful to food safety and human health. Thus, it is necessary to develop sensitive, selective and reliable analytical methods for PAT detection. In this study, a sensitive aptasensor based on a dual-signaling strategy was fabricated, in which a methylene-blue-labeled aptamer and ferrocene monocarboxylic acid in the electrolyte acted as a dual signal, for monitoring PAT. To improve the sensitivity of the aptasensor, an in-plane gold nanoparticles-black phosphorus heterostructure (AuNPs-BPNS) was synthesized for signal amplification. Due to the combination of AuNPs-BPNS nanocomposites and the dual-signaling strategy, the proposed aptasensor has a good analytical performance for PAT detection with the broad linear range of 0.1 nM-100.0 µM and the low detection limit of 0.043 nM. Moreover, the aptasensor was successfully employed for real sample detection, such as apple, pear and tomato. It is expected that BPNS-based nanomaterials hold great promise for developing novel aptasensors and may provide a sensing platform for food safety monitoring.

Electrostatic assembly of gold nanoparticles on black phosphorus nanosheets for electrochemical aptasensing of patulin.

An aptamer based impedimetric assay for the mycotoxin patulin (PAT) is described. A glassy carbon electrode (GCE) was modified with black phosphorus nanosheets (BP NSs) and modified with PAT aptamer by electrostatic attraction. Detection is based on the variations of electron transfer resistance at the modified electrode surface. This assay can detect PAT over a linear range that extends from 1.0 nM to 1.0 µM with a 0.3 nM detection limit. To improve the performance of the sensor, the BP NS-GCE was further modified with gold nanoparticles and then with thiolated PAT aptamer. This modified electrode, operated at an applied potential of 0.18 V (vs. Ag/AgCl), has a wider linear range (0.1 nM to 10.0 µM) and a lower detection limits (0.03 nM). Both assays were successfully applied to the analysis of (spiked) genuine food samples. Graphical abstract Black phosphorus nanosheets (BP NSs) were used to fabricate an aptamer based assay for patulin. To further improve the performance of the electrode, gold nanoparticles (AuNP) were placed on the surface of black phosphorus nanosheets (AuNP-BP NSs) by electrostatic attraction for patulin aptasensing.

Controlled synthesis of Au@Pd core-shell nanocomposites and their application for electrochemical sensing of hydroquinone.

In this study, a facile and effective method for the synthesis of Au@Pd nanocomposites via a chemical reduction method was proposed. Moreover, a novel electrochemical sensor based on the Au@Pd core-shell nanocomposites were constructed and used for detection of hydroquinone (HQ). The morphologies and structures of Au nanorods (NRs) and Au@Pd nanomaterials were characterized by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and electrochemical methods. By tuning the amount of Pd precursor, different Au@Pd core-shell nanocomposites were gained. It could be clearly shown that the Au3@Pd6 (nAu:nPd = 3:6) modified the glassy carbon electrode (Au3@Pd6/GCE) possessed a sensitive electrochemical response toward HQ and the oxidation peak appeared at nearly 0 V at the potential window range of -0.3 to 0.3 V. Meanwhile, the experimental results found a broad concentration range of 4-5000 µM, a low detection limit of 0.63 µM and desirable sensitivity of 1.127 mA mM-1 cm-2. The mentioned sensor was successfully applied for HQ determination in the lake water and tap water samples. It is expected that the proposed method can be used for the synthesis of other metal nanostructures with distinguished electrocatalytic abilities and used for environmental monitoring of hydroquinone.

Novel electrochemical sensing platform for ultrasensitive detection of cardiac troponin I based on aptamer-MoS2 nanoconjugates.

Cardiac troponin I (cTnI) is a specific and sensitive biomarker for the early diagnosis of acute myocardial infarction and for the subsequent clinical treatments. In this work, novel electrochemical sensing platform for sensing of cTnI based on aptamer-MoS2 nanoconjugates was proposed. For comparison, core-shell Au@SiO2@Au nanoparticles were also used for sensing of cTnI. The sensing schemes and electrochemical responses of the proposed sensors were investigated by electrochemical impedance spectroscopy (EIS) in 5.0 mM K3[Fe(CN)6]/K4[Fe(CN)6] (1:1) solution containing 0.1 M KCl, respectively. Results showed that the aptamer-Au@SiO2@Au based aptasensor shows a linear rage of 10 pM-10.0 µM with the detection limits of 1.23 pM For the aptamer-MoS2 nanosheets based aptasensor, the linear range for cTnI detection was from 10 pM to 1.0 µM with a lower detection limit of 0.95 pM Meanwhile, both the sensors were successfully applied for detection of cTnI in human blood samples. The two kinds of aptsensors have been successfully used for detecting of cTnI in human blood serums. Moreover, no negligible signal changes could be observed in the presence of non-targets of CK-MB and Myo, suggesting the good potential for clinic diagnosis.