Co, Fe Dual-Doped MoS2 Nanosheets on Polypyrrole Microtubes as Effective Peroxidase Mimics for Glutathione Sensing

Heteroatom doping is considered an effective way to enhance the catalytic activity of MoS2 nanosheets (NSs). In the paper, dual-metal doping was proposed to incorporate Fe and Co into hierarchical MoS2 ultrathin NSs, which grew directly on polypyrrole microtubes (Fe, Co-MoS2@PPy), for the enhanced enzyme-like catalytic reaction. The particular hollow tubular structure realized effective electron transfer. The doped Fe and Co tuned the electronic architecture of the MoS2 NSs to enhance the enzyme-like catalytic activity. The abundant exposed void spaces facilitated ion diffusion/penetration between the PPy interlayer and Fe-Co doped MoS2 shell, leading to heterostructured synergistic effects. Therefore, the synthesized Fe and Co-MoS2@PPy composites showed remarkable catalytic activity. The high catalytic efficiency of Fe and Co-MoS2@PPy was confirmed with the reaction of tetramethylbenzidine (TMB) and H2O2 for visible detection. The blue color disappeared after adding glutathione (GSH). Thus, this procedure was used as a convenient way to detect GSH with a detection limit of 0.76 μM. The dual-metal-doped strategy was confirmed to improve the performance of MoS2 nanocomposites and could be used as a promising matrix for other applications, such as electrochemical energy conversion, medical diagnosis, and others.

Magnetic copper silicate and boronic acid-conjugated AuNCs@keratin-based electrochemical/fluorescent dual-sensing for carcinoembryonic antigen

Boronic Acid Sensitivity, selectivity, and reliability are of great importance for tumor diagnosis. Herein, we proposed a novel electrochemical and fluorescent dual-sensing strategy to detect carcinoembryonic antigens (CEA). To this end, monodisperse spindle-like magnetic copper silicate (FeOx@C@CS) was prepared with multiple active sites to immobilize the CEA antibody. Moreover, magnetic properties improved the anti-interference ability and sensitivity to endow the assay for complex samples. In addition, boronic acid-conjugated gold nanocluster (AuNCs@keratin-BA) was prepared as an electrochemical and fluorescent dual-signal indicator. Thus, the sandwich structure of FeOx@C@CS/CEA/AuNCs@keratin-BA was formed for electrochemical/fluorescent dual-modality assay. Under optimal conditions, the quantitation range of 12.5 fg mL-1-37.5 pg mL-1 and detection limit of 4.3 fg mL-1 were obtained for the electrochemical strategy. The fluorescence detection owned the linear range of 0.05 pg mL-1-7.5 pg mL-1 with a detection limit of 0.025 pg mL-1. Dual-modality assay improved the accuracy and efficiency of CEA detection to meet the requirement of tumor diagnosis, while chemical identification and signal transduction lay an important foundation for engineering advanced nanomaterials for clinical applications.

Keratin-inorganic hybrid nanoflowers decorated with Fe3O4 nanoparticles as enzyme mimics for colorimetric detection of glucose

Fe3O4 magnetic nanoparticles (MNPs) are highly active enzyme-like catalysts. However, low stability is still a big challenge for Fe3O4-based enzyme mimics because the Fe3O4 MNPs can be easily dissolved when exposed to acidic conditions. Inspired by the numerous catalytic sites of a flower-like structure and the biological functions of amino acids in structural proteins, herein, by employing keratin as a protein component, stable Fe3O4-based MNP embedded keratin-Cu3(PO4)2 nanoflowers were constructed, from which hierarchical nanostructures with a three-dimensional petal-like morphology were selected for subsequent studies owing to their excellent enzymic catalytic activity. The keratin-nanoflower@Fe3O4 exhibited significantly enhanced catalytic activity compared with that of keratin-Cu3(PO4)2 nanoflowers and individual Fe3O4 MNPs. Remarkably, keratin-nanoflower@Fe3O4 exhibited superior long-term stability to Fe3O4 MNPs under more acidic conditions and favorable reusability. This method has been successfully exploited for the colorimetric determination of glucose in human serum with satisfactory sensitivity and specificity, offering a novel approach for glucose detection.

Rapid colorimetric sensing of ascorbic acid based on the excellent peroxidase-like activity of Pt deposited on ZnCo2O4 spheres

Pt/ZnCo₂O₄ composites were firstly found to act as artificial peroxidases and used to construct colorimetric sensing platforms for detecting H₂O₂ and ascorbic acid.