Theranostic Magnetic Nanostructures (MNS) for Cancer

Abstract

Despite the complexities of cancer, remarkable diagnostic and therapeutic advances have been made during the past decade, which include improved genetic, molecular, and nanoscale understanding of the disease. Physical science and engineering, and nanotechnology in particular, have contributed to these developments through out-of-the-box ideas and initiatives from perspectives that are far removed from classical biological and medicinal aspects of cancer. Nanostructures, in particular, are being effectively utilized in sensing/diagnostics of cancer while nanoscale carriers are able to deliver therapeutic cargo for timed and controlled release at localized tumor sites. Magnetic nanostructures (MNS) have especially attracted considerable attention of researchers to address cancer diagnostics and therapy. A significant part of the promise of MNS lies in their potential for “theranostic” applications, wherein diagnostics makes use of the enhanced localized contrast in magnetic resonance imaging (MRI) while therapy leverages the ability of MNS to heat under external radio frequency (RF) field for thermal therapy or use of thermal activation for release of therapy cargo. In this chapter, we report some of the key developments in recent years in regard to MNS as potential theranostic carriers. We describe that the r2 relaxivity of MNS can be maximized by allowing water (proton) diffusion in the vicinity of MNS by polyethylene glycol (PEG) anchoring, which also facilitates excellent fluidic stability in various media and extended in vivo circulation while maintaining high r2 values needed for T2-weighted MRI contrast. Further, the specific absorption rate (SAR) required for thermal activation of MNS can be tailored by controlling composition and size of MNS. Together, emerging MNS show considerable promise to realize theranostic potential. We discuss that properly functionalized MNS can be designed to provide remarkable in vivo stability and accompanying pharmacokinetics exhibit organ localization that can be tailored for specific applications. In this context, even iron-based MNS show extended circulation as well as diverse organ accumulation beyond liver, which otherwise renders MNS potentially toxic to liver function. We believe that MNS, including those based on iron oxides, have entered a renaissance era where intelligent synthesis, functionalization, stabilization, and targeting provide ample evidence for applications in localized cancer theranostics.

Magnetic Nanoparticles for Precision Oncology: Theranostic Magnetic Iron Oxide Nanoparticles for Image-Guided and Targeted Cancer Therapy

“…Sensitivity and specificity of cancer detection by MRI using nontargeted or targeted IONPs have been demonstrated in experimental animals as well as in human patients [32][33][34]. Results of those studies showed that core size, shape, surface property and functionalization of IONPs affect in vivo biodistribution, blood half-life, stability, pharmacokinetics, targeted delivery and MRI contrast intensity.…”

Nanodiamond–Gadolinium(III) Aggregates for Tracking Cancer Growth In Vivo at High Field

“…There are numerous reports of Gd(III)–nanoparticle formulations with high cell labeling efficiency and imaging efficacy. 1,2,5,10,20–23 In particular, carbon-based nanomaterials bearing Gd(III) ions such as gadographene, gadofullerene, and gadonanotubes have been explored. 21,24–27 However, a majority of these constructs have not enabled long-term cell labeling and fate mapping in vivo due to limited stability in biological media.…”

PSMA targeted docetaxel-loaded superparamagnetic iron oxide nanoparticles for prostate cancer

“…However, Cellax ™ (a covalently conjugated Dtxl onto polyethylene glycol-acetylated carboxymethylcellulose to form self-assembled 120 nm particles) [12–14] and BIND-014 (Dtxl encapsulated in biodegradable polymer based nanoparticles) [15, 16] are emerging as clinically useful nanoformulations. Among various nanoparticle based drug nanoformulations, superparamagnetic iron oxide nanoparticles (SPION) or magnetic nanoparticles (MNPs) have recently received considerable attention as theranostic applications [therapy (drug delivery, hyperthermia) and diagnosis (MR imaging, tumor cell-isolation)] due to their biocompatibility and superparamagnetic properties [17–20]. Therefore, formulation of docetaxel with SPION would not only enhance its biological activity but also add imaging capability to the treatment modality.…”