NiCoO2@CMK-3 composite with nanosheets-mesoporous structure as an efficient oxygen reduction catalyst

A novel metal-organic framework based electrochemical immunosensor for the rapid detection of Salmonella typhimurium detection in milk

Salmonella is one of the most prevalent pathogens causing foodborne diseases. In this study, a novel electrochemical immunosensor was designed for the rapid and accurate detection of Salmonella typhimurium (S. typhimurium) in milk. Platinum nanoparticles and Co/Zn-metal-organic framework @carboxylic multiwalled carbon nanotubes in the immunosensor acted synergistically to enhance the sensing sensitivity and stability. The materials and sensors were characterised using X-ray diffractometry, scanning electron microscopy, Fourier-transform infrared spectroscopy, differential pulse voltammetry, cyclic voltammetry, and other techniques. The optimised immunosensor showed a linear response for S. typhimurium concentrations in the range from 1.3 × 102 to 1.3 × 108 CFU mL-1, with a detection limit of 9.4 × 101 CFU mL-1. The assay also demonstrates good specificity, reproducibility, stability, and practical application potential, and the method can be extended to other foodborne pathogens.

Fabrication of an affordable and sensitive corticosteroid-binding globulin immunosensor based on electrodeposited gold nanoparticles modified glassy carbon electrode

Herein, we fabricated an ultrasensitive electrochemical immunosensor for the quantitative detection of corticosteroid-binding globulin (CBG). CBG is a protein that regulates glucocorticoid levels and is an important biomarker for inflammation. A decrease in CBG levels is a key biomarker for inflammatory diseases, such as septic shock. To enhance the electrochemical performance and provide a large surface area for anti-CBG immobilization, we functionalized the glassy carbon electrode surface with AuNPs. Electrochemical characterization methods including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to examine the construction of the fabricated immunosensor. The electrochemical signal demonstrated a remarkable sensitivity to the CBG antigen, with a detection range from 0.01 to 100 μg/mL and a limit of detection of 0.012 μg/mL, making it suitable for both clinical and research applications. This label-free immunosensor offers significant advantages, including high sensitivity, low detection limits and excellent selectivity, making it a promising tool for detecting CBG in complex biological samples. Its potential applications include early disease diagnosis, treatment monitoring and studying CBG-related physiological processes.

Sandwich-type immunosensor based on aminated 3D-rGOF-NH2 and CMK-3-Fc-MgAl-LDH multilayer nanocomposites for detection of CA125

Cancer antigen 125 (CA125)1 is the most important biological screening indicator used to monitor epithelial ovarian cancers, and it plays a vital role in distinguishing ovarian cancers from benign diseases. Biosensors show great potential in the analysis and detection of disease markers. In this study, we designed electrochemical sensors based on three-dimensional amino-functionalized reduced graphene oxide (3D-rGOF-NH2),2 MgAl layered double hydroxide nanocomposites containing ordered mesoporous carbon (CMK-3),3 and ferrocene carboxylic acids（Fc-COOH）4for the detection of CA125. 3D-rGOF-NH2 possesses good conductivity, a large surface area, and high porosity, enabling more immobilized nanoparticles to be deposited on its surface with excellent stability. CMK-3@Fc@MgAl-LDH nanocomposite was used as a carrier to enhance the immobilization of antibodies and the loading of Fc, conductors to enhance conductivity, and enhancers to gradually amplify the signal of Fc. The surface morphology, elemental composition, and surface groups of the materials were characterized using scanning electron microscopy (SEM),5 transmission electron microscopy (TEM),6 and X-ray diffraction (XRD)7 techniques. The response signal of the electrochemical sensor was measured by DPV. Under the optimal conditions, the electrochemical sensor obtained a linear detection range of 0.01 U/mL-100 U/mL with a detection limit of 0.00417 U/mL.

Detection of CYFRA21-1 in serum by electrochemical immunosensor based on nanocomposite consisting of AuNPs@CMK-3@CMWCNTs

An electrochemical immunosensor based on the modification of nanocomposite was constructed to detect the lung cancer marker Cytokeratin 19 fragment antigen 21-1 (CYFRA21-1). Ordered mesoporous carbon CMK-3 was selected to mix with carboxylated multi-walled carbon nanotubes (CMWCNTs), and their combination could enhance electron transfer efficiency and amplify the electrochemical signal. Furthermore, aurum nanoparticles (AuNPs) were further mixed with the hybrid carbon nanomaterials, which bind antibodies via Au-S bonds and provide numerous of binding sites for antibodies. Finally, CYFRA21-1 could be detected by specific immune response between antigen and antibody by improving the immunosensor sensitivity. The characterization of scanning electron microscopy (SEM) showed that AuNPs were embedded on the surface and interstices of CMK-3@CMWCNTs. The curves of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) showed that the immunsensor was successfully constructed. The constructed immunosensor had a linear range of 0.5 pg/mL to 10⁵ pg/mL for the detection of CYFRA21-1 in serum, and the correlation coefficient (r) was 0.998, with a detection limit of 0.2 pg/mL. Thus, this method is selective and sensitive for getting the accurate and reliable detection results and provides a new method for the CYFRA21-1 ultrasensitive detection in serum.

Adsorption performance of CMK-3 and C-FDU-15 in NO removal at low temperature

CMK-3 and C-FDU-15 samples were synthesized using hard-templating and evaporation-induced self-assembly (EISA) methods, respectively. The pore structures of CMK-3 and C-FDU-15 as well as commercial activated carbon were characterized by means of X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and N₂ adsorption-desorption. Adsorption of NO was investigated by means of thermogravimetric analysis, temperature-programmed desorption of NO + O₂, and in situ diffuse reflectance Fourier transform infrared spectroscopy. The results show that the CMK-3 and C-FDU-15 materials possessed ordered and uniform structures. The co-adsorption capacity of NO and O₂ decreased in the sequence CMK-3 (88.6 mg/g) > C-FDU-15 (71.7 mg/g) > AC (25.3 mg/g). There were two main adsorption species on CMK-3 and C-FDU-15: nitrite and nitrate. Nitrite is converted to nitrate easily. However, the adsorption species were more complex on AC, with nitrite being the main species. Moreover, CMK-3 and C-FDU-15 exhibit excellent regeneration efficiency compared with AC. The excellent NO adsorption performance of CMK-3 and C-FDU-15 was associated with their ordered mesoporous structures and high surface areas. The research provides more options for NO adsorption in the future.