A novel Nb2C MXene based aptasensor for rapid and sensitive multi-mode detection of AFB1.

Rapid and accurate on-site detection of aflatoxin B1 (AFB1) is of great significance for ensuring food safety. This work developed a dual mode aptasensor and a dual channel artificial neural network (ANN) intelligent sensor detection platform for simple and convenient quantitative detection of AFB1 in food. This sensor was prepared by encoding manganese ion (Mn2+) mediated surface concave niobium carbide MXene nanomaterials (Nb2C-MNs) using fluorescent group labeled aptamers (ssDNA-FAM). Mn2+-mediated Nb2C-MNs exhibited better peroxidase-like and fluorescence quenching properties. Moreover, ssDNA-FAM as a fluorescent probe for the sensor also significantly enhanced the enzyme activity of Nb2C-MNs. When AFB1 existed, ssDNA-FAM preferentially bonded to AFB1, resulting in fluorescence signal recovery and colorimetric signal weakening. Consequently, the multimodal biosensor could achieve fluorescence/colorimetric detection without the need for material and reagent replacement. In on-site detection, both ratio fluorescence and colorimetric signals could be collected using smartphones and analyzed and modeled on the developed ANN platform, achieving visual intelligent sensing. This multimodal biosensor had a detection line as low as 0.0950 ng/mL under optimal conditions, and also had the advantages of simple operation, fast and sensitive, and high specificity, which can meet the real-time on-site detection needs of AFB1 in remote areas.

A novel multimode biosensor for sensitive detection of AFB1 in food based on Mxenes nano enzymes.

In this work, Ti3C2 nano-enzymes (Ti3C2 NEs) materials with simulated peroxidase activity and fluorescence quenching properties were prepared. Then Ti3C2 NEs was functionalized using 6-carboxyfluorescein (FAM) labeled Aflatoxin B1 (AFB1) aptamers to construct a novel multimode nano enzyme biosensor for the detection of AFB1 in peanuts. Based on the fluorescence quenching characteristics and the superior simulated peroxidase activity of Ti3C2 NES and the specific binding of the aptamer to AFB1, the sensitive and rapid fluorescence/colorimetric/smart phone detection of AFB1 have been achieved, with detection limits of 0.09 ng mL-1, 0.61 ng mL-1 and 0.96 ng mL-1, respectively. The analytical method provided can not only detect AFB1 in multiple modes, but also has a wider detection range, lower limit of detection (LOD) and better recovery rate, and can achieve on-site accurate detection of AFB1 content in peanuts, which has great application potential in the field of food quality testing.

Study on the Mechanical Properties of Monocrystalline Germanium Crystal Planes Based on Molecular Dynamics.

Nanoindentation and atomistic molecular dynamics simulations of the loading surface of monocrystalline germanium were used to investigate the evolution of the key structure, the force model, the temperature, the potential, and the deformable layer thickness. The mechanical characteristics of typical crystal planes (001), (110), and (111) of the crystal system were compared under load. It was observed that the hardness and stiffness of the (110) plane were greatest among the three crystal planes, whereas the hardness and stiffness of the (111) plane were lowest. Moreover, the deformation layers at the ends of both planes were basically flat. The processing efficiency of the (111) surface was higher; thus, the (111) surface was considered the best loading surface. It was concluded that the subsurface defects of the monocrystalline germanium (111) plane were smaller and the work efficiency was higher during the processing of monocrystalline germanium, making it ideal for monocrystalline germanium ultra-precision processing.