Plasmon-enhanced electroreduction activity of Au-AgPd Janus nanoparticles for ochratoxin a detection

Construction of Biomimetic Nanochannel, Property Regulation, and Biomarker Detection

The significance of biomimetic nanochannel in the field of biosensors is gaining increasing recognition. The controllable construction of biomimetic nanochannels and their performance modulation have demonstrated great importance and obtained wide interest. The nanochannels offer high sensitivity, enabling sensors to swiftly identify target biomarkers in complex biological samples, with detection limits reaching the picomolar level. Furthermore, they demonstrate exceptional selectivity and reproducibility, making them ideal tools for biomarker detection. In recent years, biosensors utilizing biomimetic nanochannel have shown remarkable performance in detecting a wide range of biomarkers. This review aims to explore the opportunities and challenges associated with biomimetic nanochannel technology in biosensor applications, focusing on the construction and performance modulation of these nanochannels, as well as their applications in detecting nucleic acids, proteins, organisms, and small molecules. Providing forward-looking insights into this cutting-edge field is aspired, with particular emphasis on technological advancements, addressing current challenges, and discussing future trends.

A colorimetric/SERS dual-mode sensor based on ferric ion-dopamine@Au-Ag-Au Janus NPs for acrylamide determination in baked goods

This study successfully developed a colorimetric/SERS dual-mode sensor for determining acrylamide in baked goods based on the excellent peroxidase-like activity and Raman activity of Fe-PHS@Au-Ag-Au Janus NPs. In colorimetric mode, the thiol-ene Michael addition between acrylamide (AA) and glutathione (GSH) efficiently eliminates GSH-induced peroxidase-like activity inhibition. The peroxidase-like activity of Fe-PHS@Au-Ag-Au Janus NPs gradually recovered, and the blue color of the solution gradually deepened with the increase in AA dosage. In surface-enhanced Raman spectroscopy (SERS), Apt-Fe-PHS@Au-Ag-Au Janus NPs can selectively capture AA and bind specifically, leading to the dissociation of Apt and Fe-PHS@Au-Ag-Au Janus NPs. The Raman activity of Apt-Fe-PHS@Au-Ag-Au Janus NPs decreases due to the dissociation of Apt. The dual-mode sensor was utilized for the determination of acrylamide in the concentrations range from 0.05 to 20 µg·L-1 with detection limits of 0.06 µg·L-1 (SERS) and 0.01 µg·L-1 (colorimetric). The recovery in baked samples was between 91.0 and 108.0%.

A SERS "on-off" sensor for Hg2+ and fumonisin B1 determination in grains based on Au-Janus Ag NPs modified by carbon dots

Se-WCDs-Au-Janus Ag NPs with weak oxidase activity were synthesized using Se-W carbon dots (Se-WCDs) as stabilizers and reducing agents. These Janus nanoparticles (Janus NPs) effectively catalyze the reduction of mercury ions (Hg2+) to metallic mercury (Hg0), generating Au-Ag-Hg mercury alloys (Au-Ag@HgNPs). The aggregated Au-Ag@HgNPs on the nanoparticles improve the SERS activity of Se-WCDs-Au-Janus Ag NPs through a synergistic effect of electromagnetic enhancement and chemical enhancement. Interestingly, adding FB1 turns off the Raman signal by inhibiting the aggregation of Au-Ag@HgNPs. Based on these findings, a SERS "on-off" sensor utilizing the Se-WCDs-Au-Janus Ag NPs as the probe was successfully developed to determine fumonisin B1 (FB1) and Hg2+ in grains. The detection limits were as low as 0.005 μg·L-1 for Hg2+ and 0.006 μg·L-1 for FB1.

Electroactive RuPt NPs programmed dual-channel electrochemical sensor for methyl mercaptan monitoring

The accurate and sensitive detection of methyl mercaptan (CH3SH) was of great significance for food corruption monitoring. Electroactive labels engineered electrochemical sensors possessed tailorable electrochemical responses, and showed potential prospects for CH3SH monitoring. In comparison to a single electrochemical signal, electroactive nanocomposites with multiple electrochemical responses not only provided multi-channel sensing signals for accurate detection, but also increased the peak intensity for sensitive detection. Herein, RuPt NPs were designed and explored to possess two independent and non-interfering electrochemical oxidation peaks at 0.75 V and -0.73 V. The formation of metal-SH covalent bonds between electroactive sites of RuPt NPs and CH3SH induced the changes of two electrochemical oxidation peaks. By utilizing the sum intensity of two electrochemical peaks as detection signal, a dual-channel electrochemical sensor was established for CH3SH detection in the range of 1 μM-1 mM, and had a low limit of detection (LOD) of 300 nM. This work gave a new insight into promoting more electroactive nanocomposites with multiple signals for accurate and sensitive electrochemical detection applications.

SERS aptasensor detection of aflatoxin B1 based on silicon-au-ag Janus nanocomposites

Aflatoxin B1 (AFB1) is a prevalent contaminant in maize, posing significant threats to human health. This study designed AuAg Janus NPs with intrinsic Raman signals as signal probes and SiO2@AgNPs as capture probes. The two were coupled through complementary base pairing to ensure the ordered, controlled distribution of noble metal nanoparticles. The AuAg Janus NPs and the highly stable SiO2 carrier is expected to avoid the adverse effects on stability caused by using signal molecules and the formation of random aggregates when using the noble metal nanoparticle gap effect to concentrate on the electromagnetic field. This study improved the negative impact of AgNPs' high surface energy on their uniformity, while enhancing the pH adaptability of AuAg Janus NPs. In the presence of AFB1, the composite disintegrates, and the SERS intensity showed a negative correlation with AFB1 concentration, enabling highly sensitive and stable detection of AFB1.

RuZn NPs with electroactivity and oxidase-like property for dual-mode anti-cancer drug monitoring

6-mercaptopurine (6-MP) as the effective anti-cancer drug was used for the treatment of Crohn's disease and acute lymphoblastic leukaemia, but the response to maintenance therapy was variable with individual differences. In order to control the dosage and decrease the side effects of 6-MP, a sensitive and stable assay was urgently needed for 6-MP monitoring. Herein, RuZn NPs with electrochemical oxidation property and oxidase-like activity was proposed for dual-mode 6-MP monitoring. Burr-like RuZn NPs were prepared and explored to not only exhibit an electrochemical oxidation signal at 0.78 V, but also displayed excellent oxidase-like performances. RuZn NPs were utilized for the dual-mode monitoring of 6-MP, attributing to the formation of Ru-SH covalent bonding. The colorimetric method showed good linearity from 10 μM to 5 mM with the limit of detection (LOD) of 300 nM, while the electrochemical method provided a higher sensitivity with the LOD of 37 nM in range from 100 nM to 200 μM. This work provided a new way for the fabrication of dual-functional nanotags with electroactivity and oxidase-like property, and opened a dual-mode approach for the 6-MP detection applications with complementary and satisfactory results.

Chiral Ru-Based Covalent Organic Frameworks as An Electrochemiluminescence-Active Platform for the Enantioselective Sensing of Amino Acids

Although several studies related with the electrochemiluminescence (ECL) technique have been reported for chiral discrimination, it still has to face some limitations, namely, complex synthetic pathways and a relatively low recognition efficiency. Herein, this study introduces a facile strategy for the synthesis of ECL-active chiral covalent organic frameworks (COFs) employed as a chiral recognition platform. In this artificial structure, ruthenium(II) coordinated with the dipyridyl unit of the COF and enantiopure cyclohexane-1,2-diamine was harnessed as the ECL-active unit, which gave strong ECL emission in the presence of the coreactant reagent (K2S2O8). When the as-prepared COF was used as a chiral ECL-active platform, clear discrimination was observed in the response of the ECL intensity toward l- and d-enantiomers of amino acids, including tryptophan, leucine, methionine, threonine, and histidine. The biggest ratio of the ECL intensity between different configurations was up to 1.75. More importantly, a good linear relationship between the enantiomeric composition and the ECL intensity was established, which was successfully employed to determine the unknown enantiomeric compositions of the real samples. In brief, we believe that the proposed ECL-based chiral platform provides an important reference for the determination of the configuration and enantiomeric compositions.