Recent Advances in Synthesis and Application of Metal Oxide Nanostructures in Chemical Sensors and Biosensors

Nanostructured materials formed from metal oxides offer a number of advantages, such as large surface area, improved mechanical and other physical properties, as well as adjustable electronic properties that are important in the development and application of chemical sensors and biosensor design. Nanostructures are classified using the dimensions of the nanostructure itself and their components. In this review, various types of nanostructures classified as 0D, 1D, 2D, and 3D that were successfully applied in chemical sensors and biosensors, and formed from metal oxides using different synthesis methods, are discussed. In particular, significant attention is paid to detailed analysis and future prospects of the synthesis methods of metal oxide nanostructures and their integration in chemical sensors and biosensor design.

Fabrication and application of nanoporous anodic aluminum oxide: a review

Due to the unique optical and electrochemical properties, large surface area, tunable properties, and high thermal stability, nanoporous anodic aluminum oxide (AAO) has become one of the most popular materials with a large potential to develop emerging applications in numerous areas, including biosensors, desalination, high-risk pollutants detection, capacitors, solar cell devices, photonic crystals, template-assisted fabrication of nanostructures, and so on. This review covers the mechanism of AAO formation, manufacturing technology, the relationship between the properties of AAO and fabrication conditions, and applications of AAO. Properties of AAO, like pore diameter, interpore distance, wall thickness, and anodized aluminum layer thickness, can be fully controlled by fabrication conditions, including electrolyte, applied voltage, anodizing and widening time. Generally speaking, the pore diameter of AAO will affect its specific application to a large extent. Moreover, manufacturing technology like one/two/multi step anodization, nanoimprint lithography anodization, and pulse/cyclic anodization also have a major impact on overall array arrangement. The review aims to provide a perspective overview of the relationship between applications and their corresponding AAO pore sizes, systematically. And the review also focuses on the strategies by which the structures and functions of AAO can be utilized.

Vertical capacitance aptasensors for real-time monitoring of bacterial growth and antibiotic susceptibility in blood

For the treatment of bacteremia, early diagnosis and rapid antibiotic susceptibility tests (ASTs) are necessary because survival chances decrease significantly if the proper antibiotic administration is delayed. However, conventional methods require several days from blood collection to AST as it requires three overnight cultures, including blood culture, subculture, and AST culture. Herein, we report a more rapid method of sensing bacterial growth and AST in blood based on a vertical capacitance sensor functionalized with aptamers. Owing to their vertical structure, the influence of blood cells sunk by gravity on capacitance measurements were minimized. Thus, bacterial growth in blood at 10⁰-10³ CFU/mL was monitored in real-time by measuring changes in capacitance at f = 10 kHz. Moreover, real-time capacitance measurements at f = 0.5 kHz provided information on biofilm formation induced during blood cultures. Bacterial growth and biofilm formation are inhibited above the minimal inhibitory concentration of antibiotics; therefore, we also demonstrated that vertical capacitance aptasensors could be applied to rapid AST from positive blood cultures without a need for the subculture process.