This study demonstrates a new candidate for targeted magnetic resonance imaging (MRI) contrast agent (CA) based on holmium nanoparticles. MRI is one of the most powerful diagnostic tools in cancer diagnosis which enables anatomical images of soft tissues with a resolution much higher than other imaging techniques. Holmium has been known for its high magnetic moment which can improve MRI signals as T2-MRI CA. This research focuses on modifying folic acid (FA) on the surface of polyethyelene glycol coated- holmium nanoparticles to deliver holmium nanoparticles selectively to the cancer-overexpressed FA receptors, such as cervical cancer. Their preparation and characterization with several analytical instruments such as transmission electron microscopy to observe their shape and size, thermal gravimetric analysis, ultraviolet and infrared spectroscopies to investigate the FA and polyethylene glycol molecules on nanoparticles are also included. From the results, morphology images show a narrow size distribution below 20 nm after the functionalization of polyethyelene glycol-coated holmium nanoparticles with and without FA modification. Based on ultraviolet and infrared spectrum analysis, the presences of FA and polyethylene glycol molecules on nanoparticles were also identified. The typical peaks of FA at around 280 and 360 nm were found on FA-modified nanoparticles spectras. In addition, infrared spectroscopy results at around 2800 cm^–1 originated from polyethylene glycol molecules on nanoparticles was also observed. Furthermore, based on a preliminary cytotoxicity study, there are no significant differences between polyethylene glycol-coated nanoparticles modified with and without FA in terms of toxicity. Based on these results, FA-modified holmium nanoparticles showed promising preliminary results to be utilized as targeted MRI CA for diagnostic purposes.

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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.@en

Multifunctional, biocompatible magnetic materials, such as iron oxide nanoparticles (IONPs), hold great potential for biomedical applications including diagnostics (e.g., MRI) and cancer therapy. In particular, they can play a crucial role in advancing cancer thermotherapy by generating heat when administered intratumorally and when exposed to an alternating magnetic field. This heat application is often combined with radio- (chemo)therapy and/or imaging. Consequently, the design of materials for such a multimodal approach requires hybrid nanoparticles that retain their magnetic properties while integrating additional functionalities. This work introduces synthesis and investigation of magnetically enhanced nanoparticles with a palladium core (envisioned for future radiolabeling with therapeutic 103Pd) and a magnetic iron oxide shell containing paramagnetic manganese (Pd/Fe|(nMn)-oxide, n = 0.25 and 0.5). Doping the iron oxide lattice with Mn significantly increases magnetic saturation, boosting specific loss power up to 1.7 times compared to that of undoped analogs. Interestingly, higher Mn-content in Pd/Fe|(0.5Mn)-oxide leads to a pronounced Mn outer rim, enhancing the heating efficiency at 346 kHz and 23 mT and contributing to the water exchange on the surface of the paramagnetically doped nanoparticles, resulting in additional T1 MRI contrast. The enhanced magnetic properties of the hybrid Pd/Fe|Mn-oxide nanoparticles enable effective therapeutic outcomes with injection of only small quantities of the material, offering great potential for effective cancer treatment strategies that combine hyperthermia/thermal ablation with radiotherapy while allowing for real-time monitoring via MRI.@en

Gadolinium (Gd) nanoparticles (NPs) are increasingly considered as a viable alternative to clinically employed Gd chelates in magnetic resonance imaging (MRI). The utilisation of these materials as contrast agents offers several advantages including lower toxicity, prolonged circulation time, and a sufficiently high Gd content, thereby enhancing disease imaging during MRI diagnosis. Therefore, this study synthesised Gd NPs using the hydrothermal method based on the response surface methodology Box-Behnken design (RSM-BBD) to determine the optimal conditions. In this experimental design, three independent variables, the mass of Gd₂O₃ (g), the synthesis temperature (°C) and time (h), were optimised to obtain sufficiently sized nanoparticles for further biomedical applications. In addition, polyethene glycol-6000 (PEG-6000) was used as a stabiliser to form uniformly sized nanoparticles. The optimal conditions were 0.4910 g of Gd₂O₃, a temperature of 180 °C, and a synthesis time of 7 h. Characterisation by scanning electron microscope-energy dispersive X-ray (SEM-EDX) and transmission electron microscope (TEM) demonstrated that the Gd NPs were spherical with a size range below 20 nm. Fourier transform infrared (FTIR) spectroscopy identified PEG molecules with low intensity on the Gd NPs and the obtained zeta potential value was +36.7±0.802 mV. The RSM-BBD analysis applied in this study facilitated the determination of the optimal synthesis conditions.

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Information storage in vivo will lead to next-generation identification and security authentication. Here, an information storage method was proposed for in vivo application by using a pair of lanthanide-doped nanoprobes (NdNPs and ErNPs) with orthogonal emissions in the second near-infrared window. The information is stored in different fluorescence channels separately, while the selective readout could be realized by simply manipulating excitation wavelengths. The small-animal experiments primarily confirm the applicability of this method in vivo. The binary numbers ″1″ and ″0″ are implanted under the mice's skin, and the corresponding signals ″on″ and ″off″ can be collected by charge-coupled devices under different laser filter combinations. The design of lanthanide-doped probes with the nanoscale features and orthogonal emissions is expected to provide a new strategy for information storage in vivo. The lanthanide materials with excellent down-conversion near-infrared fluorescence performance have shown great application potential in the field of photonics.

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