MRI is a powerful, non-invasive imaging technique with exceptional soft tissue contrast, requiring contrast agents to enhance sensitivity by shortening longitudinal (T1) and transverse (T2) relaxation times. While most clinical agents are chelate-based, their potential toxicity has driven the development of nanoparticle-based alternatives. Nanoparticles offer reduced toxicity, improved stability, prolonged circulation time, and better control over surface properties. Lanthanide-based nanoparticles, in particular, are promising due to their paramagnetic properties enhancing MRI contrast. The design of these nanoparticles focuses on optimizing size, shape, and colloidal stability with advances in synthesis techniques allowing for precise control over particle size, morphology, and stability to significantly influence relaxivity. Larger sizes increase r₂ values but may reduce stability, while anisotropic shapes enhance relaxivity compared to the more stable spheres. Surface modifications with functional polymers improve stability and prevent aggregation, optimizing imaging performance. As research progresses, lanthanide-based nanoparticles are poised to become crucial tools in radiology-driven cancer diagnosis and therapy, offering dual functionality for early detection, targeted treatment, and minimized off-target effects. However, these nanoparticles must be refined for tumour-specific diagnostic and therapeutic applications and undergo comprehensive safety evaluations before clinical trials.

Samarium oxide (Sm₂O₃), such as electrochemical sensors, is a promising material in various application prospects and industries. Additionally, Sm₂O₃ leverages electron transport capabilities, high electrical conductivity, and thermal stability to develop an effective material in electrode modification for detecting hazardous pollutants. Hydrazine and p-nitrophenol are compounds commonly used in producing insecticides, pesticides, pharmaceuticals, and the chemical industry. However, these compounds can become hazardous environmental pollutants and pose serious health risks to humans. Therefore, this research aims to examine the impact of modifying gold electrode (GE) with Sm₂O₃ nanoparticles, characterizing the electrochemical results, and assessing sensor performance through the use of the GE/Sm₂O₃ NP electrode. In this context, the purpose is to detect hydrazine and p-nitrophenol through voltammetry, with analytical parameters including recovery, repeatability, detection limit, quantification limit, and linear range. The results show that the synthesis of Sm₂O₃ nanoparticles and the performance of the sensor and analytical parameters of GE/Sm₂O₃ NP are carried out in detecting hydrazine and p-nitrophenol using the Cyclic Voltammetry (CV) method. Furthermore, the significant increase in the current response validates the improvement of GE conductivity as an electron transporter. The sensor performance has been studied, and analytical parameters have been determined. For hydrazine and p-nitrophenol, the values are recovery of 98.74 % and 99.01 %, repeatability of 99.42 % and 98.45 %, limit of detection (LoD) of 0.4684 μM and 0.50332 μM, limit of quantification (LoQ) of 1.4194 μM and 1.5252 μM, and linear concentration range for both analytes from 0.1 μM to 7 μM.