This review discusses several aspects regarding ultrasmall magnetic nanoparticles as T ₁ contrast agents, including synthesis, parameters affecting T ₁ , and applications.

The size and composition of the protein templates are critically important to the formation, fluorescence, and stability of Au nanoclusters.

Extracellular vesicles (EVs) are membrane-enclosed particles that have attracted much attention for their potential in disease diagnosis and therapy. However, the clinical translation is limited by the dosing consistency due to their heterogeneity. Among various characterization techniques, nanoparticle tracking analysis (NTA) offers distinct benefits for EV characterization. In this review, we will discuss the NTA technique with a focus on factors affecting the results; then, we will review the two modes of the NTA techniques along with suitable applications in specific areas of EV studies. EVs are typically characterized by their size, size distribution, concentration, protein markers, and RNA cargos. The light-scattering mode of NTA offers accurate size, size distribution, and concentration information in solution, which is useful for comparing EV isolation methods, storage conditions, and EV secretion conditions. In contrast, fluorescent mode of NTA allows differentiating EV subgroups based on specific markers. The success of fluorescence NTA heavily relies on fluorescent tags (e.g., types of dyes and labeling methods). When EVs are labeled with disease-specific markers, fluorescence NTA offers an effective tool for disease detection in biological fluids, such as saliva, blood, and serum. Finally, we will discuss the limitations and future directions of the NTA technique in EV characterization.

A general approach to the synthesis and detailed characterization of magnetic ferrite nanocubes were reported, where the nanocubes were synthesized by the thermal decomposition of metal–oleate complexes following a step-heating method. The doping ions were introduced during the precursor preparation by forming M²⁺/Fe³⁺ oleate mixed complex (M²⁺ = Fe²⁺, Mn²⁺, Zn²⁺, Cu²⁺, Ca²⁺, and Mg²⁺). The mechanistic studies showed that the presence of sodium oleate in combination with step-heating was critical for the formation of the cubic shapes for the doped magnetic ferrites. The nanocubes were extensively characterized, including morphology and crytsal structure by advanced transmission electron microscopy, doping level and distribution by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, cation distribution within the spinel structures by Fourier transform infrared and Raman spectroscopy, and magnetic properties by alternating gradient magnetometer at room temperature.