Progress in Remotely Triggered Hybrid Nanostructures for Next-Generation Brain Cancer Theranostics

Progress in nanomedicine has enabled the development of smart hybrid nanostructures (HNSs) for brain cancer theranostics, a novel platform that can diagnose the brain while concurrently beginning primary treatment, initiating secondary treatments where necessary, and monitoring the therapy response. These HNSs can release guest molecules/cargoes directly to brain tumors in response to external physical stimuli. Such physical stimulation is generally referred to as remote stimuli which can be externally applied examples include alternating magnetic field, visible or near-infrared light, ultrasound radiation, X-ray, and radiofrequency. The release of therapeutic cargoes in response to physical stimuli can be performed along with photodynamic therapy, photothermal therapy, phototriggered chemotherapeutics, sonodynamic therapy, electrothermal therapy, and magnetothermal therapy. Herein, we review different HNSs currently used as remotely triggered modalities in brain cancer, such as organic-inorganic HNSs, polymer micelles, and liposomes HNSs. We also summarize underlying mechanisms of remote triggering brain cancer therapeutics including single- and two-photon triggering, thermoresponsive HNSs, photoresponsive HNSs, magnetoresponsive HNSs, and electrically and ultrasound-stimulated HNSs. In addition to a brief synopsis of ongoing research progress on "smart" HNSs-based platforms of novel brain cancer therapeutics, the review offers an up-to-date development in this field for neuro-oncologists, material/nanoscientists, and radiologists so that a rapid clinical impact can be achieved through a convergence of multidisciplinary expertise.