Current status and challenges of metallic-silica based nanotheranostics in clinical translation for cancer diagnosis and treatment

Although the new anticancer molecules have been developed, incidences of the off-target adverse effects, poor bioavailability and drug resistance have remained unsolvable problems towards cancer heterogeneity. These challenges require instant diagnosis, simultaneous therapy, real-time monitoring and personalized approach towards cancer management. The integration of silica and metal into hybrid ‘nanotheranostics’ has been extensively studied over the last decade and explored as anticancers. In this review, a concept of metal–silica nanocomposites as multimodal theranostic applications is comprehensively evaluated and compared. In fact, the approach of metal confinement not only affects the tunability of optical properties required for tumor treatment, but also modulates the drug loading and release. While assortment of the recent metal–silica applications involved in nano-fabrication is highlighted, the real scenario of the applications in clinical trials is also revealed. Consequently, the critical gaps in the design and quality control are addressed to provide outlooks of metal silica nanotheranostics in cancer.