Cyanine based Nanoprobes for Cancer Theranostics

Cyanine dyes are greatly accredited in the development of non-invasive therapy that can "see" and "treat" tumor cells via imaging, photothermal and photodynamic treatment. However, these dyes suffer from poor pharmacokinetics inducing severe toxicity to normal cells, insufficient accumulation in tumor regions and rapid photobleaching when delivered in free forms. Nanoparticles engineered to encapsulate these compounds and delivering them into tumor regions have increased rapidly, however, so far, these nanoparticles (NPs) have not proved to be so effective to circumvent existing challenges. Newly designed multifunctional smart nanocarriers that can improve phototherapeutic properties of these dyes, co-encapsulate multiple potent therapeutic compounds, and simultaneously overcome limitations related to tumor recurrence, metastases, limited intracellular uptake, and tumor hypoxia have potential to revolutionize modern paradigm of cancer therapy. Such cyanine based multifunctional nanocarriers integrating imaging and therapy in a single platform can effectively produce better clinical outcomes in cancer treatment. This review briefly summarizes recent advancements of cyanine nanoprobes that are currently used as imaging/phototherapeutic agents in unimodal/bimodal/trimodal cancer theranostics. Finally, we conclude this review by addressing challenges of pre-existing therapeutic systems and designs adopted to overcome them with a brief insight assimilating future perspective of emerging cyanine-based NPs in cancer theranostics.