Theranostic magnetic nanoparticles: Synthesis, properties, toxicity, and emerging trends for biomedical applications

Nanotechnology provides a wide range of nanosized devices, termed as nanotheranostics, that are integrated with diagnostic and therapeutic properties for real-time monitoring and treatment of diseases. In order to di-agnose and cure diseases at the cellular and molecular level, the theranostic nanomedicine must first be able to circulate throughout the body without being destroyed by the host's immune system. Further, this can be linked to a biological ligand for targeting a specific organ or tissue. Novel non-invasive diagnostic agents, such as magnetic nanoparticles (MNPs), are currently employed in magnetic resonance imaging (MRI). Previously, they have been used for imaging various diseases; but new developments have unlocked the way for targeting the drug to the cellular membrane and multi-modal imaging with MNPs. For the production of MNPs, a wide range of synthetic methods such as physical and thermal degradation, hydrothermal production, microemulsion, co -precipitation, and polyol processes have been used, which include few examples of biosynthetic techniques. One of the biggest concern with MNPs is that they have potential toxicity issues in biomedical applications. Due to their reactive surface features and their capacity to penetrate the cell and tissue membranes, MNPs can elicit a powerful cytotoxic effect and hyperthermia. Numerous laboratories have studied in vitro cellular toxicity of MNPs in a wide variety of cancer and normal cell lines, and their findings established the fact that at low concentra-tions, MNPs are nontoxic, and at high concentrations, they have marginal toxicity, demonstrating their biocompatibility and acceptable safety profile. Diagnostic imaging using nanosystems can be performed using the aforementioned approaches, including MRI, optical imaging, nuclear imaging, computed tomography, ul-trasound etc. In this article, various theranostic magnetic nanosystems are discussed in the context of their manufacturing and development for therapeutic and diagnostic use, focusing mainly on in vitro and in vivo ap-plications. Further emphasis on their potential for integrating other nanostructures with current biotechnology, as well as the special qualities of magnetic nanosystems are further highlighted to explain the future role of magnetic nanosystems in the successful therapy.