Facile and Controllable Growth of β-FeOOH Nanostructures on Polydopamine Spheres

Recent progress in magnetic polydopamine composites for pollutant removal in wastewater treatment

Various water pollution issues pose a significant threat to human water safety. Magnetic polydopamine composites (MPCs), which can be separated by magnetic fields after the adsorption process, exhibit outstanding adsorption capacity and heterogeneous catalytic properties, making them promising materials for water treatment applications. In particular, by modifying the polydopamine (PDA) coating, MPCs can acquire enhanced high reactivity, antibacterial properties, and biocompatibility. This also provides an attractive platform for further fabrication of hybrid materials with specific adsorption, catalytic, antibacterial, and water-oil separation capabilities. To systematically provide the background knowledge and recent research advances in MPCs, this paper presents a critical review of MPCs for water treatment in terms of both structure and mechanisms of effect in applications. Firstly, the impact of different PDA positions within the composite structure is investigated to summarize the optimization of properties contributed by PDA when acting as the shell, core, or bridge. The roles of various secondary modifications of magnetic materials by PDA in addressing water pollution problems are explored. It is anticipated that this work will be a stimulus for further research and development of magnetic composite materials with real-world application potential.

Unsaturated phospholipid modified FeOCl nanosheets for enhancing tumor ferroptosis

Iron-dependent accumulation of reactive oxygen species (ROS) and lipid peroxidation play key roles in ferroptosis, which has been an attractive strategy to kill tumor cells. However, the rapid annihilation of hydroxyl radicals (˙OH) produced from the Fenton reaction has become a major obstacle in inducing lipid peroxidation in cells. In this study, we develop a nano-delivery system of unsaturated phospholipid (Lip) and polyacrylic acid (PAA) functionalized FeOCl nanosheets (FeOCl@PAA-Lip). In this system, the ˙OH radicals produced from the Fenton reaction between FeOCl nanosheets and endogenous H₂O₂ of tumor cells attack Lip on the nanosheets in situ to initiate the lipid peroxidation chain reaction, which not only realizes free radical conversion but also leads to the amplification of ROS and lipid peroxides, thus enhancing tumor ferroptosis. The in vitro and in vivo results confirmed that FeOCl@PAA-Lip nanosheets exhibited specific tumor cell-killing effects, good biocompatibility, long circulation time, low side effects, high tumor targeting and an excellent tumor inhibition rate (73%). The Lip functionalization strategy offers a paradigm of enhancing ferroptosis treatment by conversion of ˙OH/phospholipid radicals/lipid peroxyl radicals and strengthening lipid peroxidation.

3D hierarchically porous magnetic molybdenum trioxide@gold nanospheres as a nanogap-enhanced Raman scattering biosensor for SARS-CoV-2

The global pandemic of COVID-19 is an example of how quickly a disease-causing virus can take root and threaten our civilization. Nowadays, ultrasensitive and rapid detection of contagious pathogens is in high demand. Here, we present a novel hierarchically porous 3-dimensional magnetic molybdenum trioxide-polydopamine-gold functionalized nanosphere (3D mag-MoO3-PDA@Au NS) composed of plasmonic, semiconductor, and magnetic nanoparticles as a multifunctional nanosculptured hybrid. Based on the synthesized 3D mag-MoO3-PDA@Au NS, a universal "plug and play" biosensor for pathogens is proposed. Specifically, a magnetically-induced nanogap-enhanced Raman scattering (MINERS) detection platform was developed using the 3D nanostructure. Through a magnetic actuation process, the MINERS system overcomes Raman signal stability and reproducibility challenges for the ultrasensitive detection of SARS-CoV-2 spike protein over a wide dynamic range up to a detection limit of 10-15 g mL-1. The proposed MINERS platform will facilitate the broader use of Raman spectroscopy as a powerful analytical detection tool in diverse fields.