Boosting the catalytic behavior and stability of a gold catalyst with structure regulated by ceria

In this work, a series of colloidal gold nanoparticles with controllable sizes and CeO2 promotion were anchored on carbon nanotubes (CNT) for the aerobic oxidation of benzyl alcohol.

Lateral Flow Immunoassay Based Colloidal Gold Nanoparticles for the Detection of Organophosphorous Pesticide (Propanoic) in Cow’s Milk

Simple, inexpensive, and high sensitive Lateral Flow Immunoassay (LFI) based colloidal gold nanoparticles antigen-coated as the label was designed for the fast determination of organophosphorus pesticide in cow’s milk samples. The developed LFI detection strip consisted of four structural zones start from the sample pad, conjugate pad, detection zone, and finally absorbent pad. Immune-sensitive zone was synthesized and functionalized with Propanoic Hapten–OVA, Goat monoclonal-anti-Propanoic antibodies were produced. Propionic -cationized ovalbumin-HPR conjugates were fabricated and identified. The antibody optimal conditions were set and the influence of pH on the analytical properties of the antibody-based gold nanoparticles was also investigated. The detection limit of the LFI for Propanoic standard into milk samples were 0.5 and 100 ng/mL, respectively. The test development time for the LFI was less than 5 min, suitable for fast on-site measuring of Propanoic.

Detection and difference analysis of the enzyme activity of colloidal gold nanoparticles with negatively charged surfaces prepared by different reducing agents

Research on the activity of nanoenzymes has always been a focus of nanomaterials. In this study, several reducing agents with different structures were used to prepare colloidal gold with a negative charge and similar size by controlling the temperature and pH. The affinity analysis of the substrate H 2 O 2 and TMB showed that the activity of colloidal gold nanoenzymes prepared by different reducing agents was in the order of Cc, Hq, Rs, Vc, Ga, Sc, Sm, St. The rule is that the enzyme activity of colloidal gold reduced by benzene ring is higher than that of colloidal gold enzyme reduced by linear chain. Finally, we discussed the activity of colloidal gold peroxidase from the number and position of isomers and functional groups, and demonstrated that the nanoenzyme activity affected the surface activity of colloidal gold, the elimination of hydroxyl radical and TMB binding efficiency.

Fabrication of Carbon Disulfide Added Colloidal Gold Colorimetric Sensor for the Rapid and On-Site Detection of Biogenic Amines

Meat is often wasted due to the perceived concerns of its shelf life and preservation. Specifically, in meat formation, biogenic amines (BAs) are the major agents to spoil them. Herein, we have developed a carbon disulfide (CS2) added colloidal gold nanoparticles-based colorimetric sensor for the rapid and on-site detection of biogenic amines. Transmission electron microscopy is used to observe the morphological changes in colloidal gold nanoparticles and aggregation behavior of CS2 added to the colloidal gold nanoparticles’ solution. Raman spectroscopic analysis is further used to characterize the peaks of CS2, Cad and CS2-Cad molecules. Absorption spectroscopy is used to estimate the colorimetric differences and diffuse reflectance spectra of the samples. The sensing analysis is performed systematically in the presence and absence of CS2. CS2 added colloidal gold nanoparticles colorimetric sensor detected the BAs with a limit of detection (LOD) value of 50.00 µM. Furthermore, the developed sensor has shown an LOD of 50.00 µM for the detection of multiple BAs at a single time. The observed differences in the colorimetric and absorption signals indicate that the structure of BAs is converted to the dithiocarbamate (DTC)-BA molecule, due to the chemical reactions between the amine groups of BAs and CS2. Significantly, the developed colorimetric sensor offers distinct features such as facile fabrication approach, on-site sensing strategy, rapid analysis, visual detection, cost-effective, possibility of mass production, availability to detect multiple BAs at a single time and appreciable sensitivity. The developed sensor can be effectively used as a promising and alternative on-site tool for the estimation of BAs.