nCP:Fe—A Biomineral Magnetic Nanocontrast Agent for Tracking Implanted Stem Cells in Brain Using MRI

Smart and Multi-Functional Magnetic Nanoparticles for Cancer Treatment Applications: Clinical Challenges and Future Prospects

Iron oxide nanoparticle (IONPs) have become a subject of interest in various biomedical fields due to their magnetism and biocompatibility. They can be utilized as heat mediators in magnetic hyperthermia (MHT) or as contrast media in magnetic resonance imaging (MRI), and ultrasound (US). In addition, their high drug-loading capacity enabled them to be therapeutic agent transporters for malignancy treatment. Hence, smartening them allows for an intelligent controlled drug release (CDR) and targeted drug delivery (TDD). Smart magnetic nanoparticles (SMNPs) can overcome the impediments faced by classical chemo-treatment strategies, since they can be navigated and release drug via external or internal stimuli. Recently, they have been synchronized with other modalities, e.g., MRI, MHT, US, and for dual/multimodal theranostic applications in a single platform. Herein, we provide an overview of the attributes of MNPs for cancer theranostic application, fabrication procedures, surface coatings, targeting approaches, and recent advancement of SMNPs. Even though MNPs feature numerous privileges over chemotherapy agents, obstacles remain in clinical usage. This review in particular covers the clinical predicaments faced by SMNPs and future research scopes in the field of SMNPs for cancer theranostics.

nCP:Fe Nanocontrast Agent for Magnetic Resonance Imaging-Based Early Detection of Liver Cirrhosis and Hepatocellular Carcinoma

Early detection of liver tumors and cirrhotic lesions by magnetic resonance imaging (MRI) remains a great challenge. Here, we report a biomineral nanocontrast agent based on iron-doped nanocalcium phosphate (nCP:Fe-CA) for magnetic resonance imaging of early-stage liver cirrhotic and hepatocellular carcinoma nodules using rat models. We have optimized an intravenously injectable, aqueous suspension of nCP:Fe-CA having an average size of 137.6 nm, a spherical shape, magnetic relaxivity of 63 mM^-1S^-1, and colloidal stability for 48 h, post-resuspension in an aqueous phase. Compared to superparamagnetic iron oxide nanoparticles (SPIONs), the optimized nCP:Fe-CA could detect liver tumor lesions as small as ∼0.25 cm, whereas the current clinical detection limit is ∼1 cm. In addition, multiple cirrhotic nodules of size <0.2 cm could be detected by nCP:Fe-CA-assisted MRI. The number of nodules observed after injecting nCP:Fe-CA was ∼3 times higher than that without CA (5-10 nodules). A biocompatibility study on healthy rats injected with nCP:Fe-CA showed unaltered liver transaminases, blood urea nitrogen, serum creatinine, and insignificant hemolysis. Furthermore, hepatobiliary clearance of nCP:Fe-CA was observed in 72 h compared to prolonged retention of SPIONs for 30 days when tested under identical conditions. Overall, the nCP:Fe-CA nanoparticles showed promising results as a biocompatible, MR contrast (T2) agent for the early-stage imaging of liver cirrhosis and hepatocellular carcinoma.

Labeling and tracking cells with gold nanoparticles

Gold nanoparticles (AuNPs) have garnered much attention as contrast agents for computerized tomography (CT) because of their facile synthesis and surface functionalization, in addition to their significant X-ray attenuation and minimal cytotoxicity. Cell labeling using AuNPs and tracking of the labeled cells using CT has become a time-efficient and cost-effective method. Actively targeted AuNPs can enhance CT contrast and sensitivity, and further reduce the radiation dosage needed during CT imaging. In this review, we summarize the state-of-the-art use of AuNPs in CT for cell tracking, including the precautionary steps necessary for their use and the difficulty in translating the process into clinical use.