Synthesis and applications of surface-modified magnetic nanoparticles: progress and future prospects

The growing use of magnetic nanoparticles (MNPs) demands cost-effective methods for their synthesis that allow proper control of particle size and size distribution. The unique properties of MNPs include high specific surface area, ease of functionalization, chemical stability and superparamagnetic behavior, with applications in catalysis, data and energy storage, environmental remediation and biomedicine. This review highlights breakthroughs in the use of MNPs since their initial introduction in biomedicine to the latest challenging applications; special attention is paid to the importance of proper coating and functionalization of the particle surface, which dictates the specific properties for each application. Starting from the first report following LaMer’s theory in 1950, this review discusses and analyzes methods of synthesizing MNPs, with an emphasis on functionality and applications. However, several hurdles, such as the design of reactors with suitable geometries, appropriate control of operating conditions and, in particular, reproducibility and scalability, continue to prevent many applications from reaching the market. The most recent strategy, the use of microfluidics to achieve continuous and controlled synthesis of MNPs, is therefore thoroughly analyzed. This review is the first to survey continuous microfluidic coating or functionalization of particles, including challenging properties and applications.

Applicability of Metal Nanoparticles in the Detection and Monitoring of Hepatitis B Virus Infection

Chronic infection with the hepatitis B virus (HBV) can lead to liver failure and can cause liver cirrhosis and hepatocellular carcinoma (HCC). Reliable means for detecting and monitoring HBV infection are essential to identify patients in need of therapy and to prevent HBV transmission. Nanomaterials with defined electrical, optical, and mechanical properties have been developed to detect and quantify viral antigens. In this review, we discuss the challenges in applying nanoparticles to HBV antigen detection and in realizing the bio-analytical potential of such nanoparticles. We discuss recent developments in generating detection platforms based on gold and iron oxide nanoparticles. Such platforms increase biological material detection efficiency by the targeted capture and concentration of HBV antigens, but the unique properties of nanoparticles can also be exploited for direct, sensitive, and specific antigen detection. We discuss several studies that show that nanomaterial-based platforms enable ultrasensitive HBV antigen detection.

Investigation of Ultradispersed Powders FexOy Obtained in the Electric Discharge Plasma

The paper shows the iron oxide powder production in the hypersonic jet of electro discharge plasma generated by a coaxial magnetoplasma accelerator with steel electrodes. The influence of gaseous atmosphere parameters has been investigated by carrying out experiments in normal atmospheric conditions and with the introduction of additional oxidant into the plasma discharge. Studies of the structure of synthesized powders and their magnetic properties have been carried out. It has been found that by introducing of additional oxidant it is possible to regulate the phase composition in the direction of increasing the yield of magnetite phase. Specific saturation magnetization decreases with decreasing of the magnetic nanoparticle sizes.