Theranostic applications of upconversion nanoparticle-based drug-delivery systems

Abstract

Upconversion nanoparticles (UCNPs) are capable of converting multiple photons (~975 nm) of lower energy to a single photon of (400-700 nm) comparatively high energy upon near-infrared (NIR) excitation. NIR radiations are non-hazardous and are able to penetrate to the deeper tissues. Besides these radiations (~970-980 nm), they do not cause autofluorescence and the tissues are pretty much transparent to the light. Further, due to low-energy excitation power, minimal cellular damage occurs. Additionally, upconverted nanoparticles emission in the visible spectrum can be utilized for diagnosis and imaging purposes. In the last few years, UCNPs have gained considerable attention in the drug delivery and theranostics because of their property to act as energy donor, biocompatible carrier, and drug carrier and their ability to convert NIR light to visible light and heat, thereby paving way to numerous applications such as theranostics, targeted delivery, sustained drug release, deep tissue imaging, and photothermal and photodynamic therapy. The unique combination of advanced drug delivery system and UCNPs in a single platform has generated significant interest in translating such system to clinical applications. Due to their unique optical and interesting biomedical applications, UCNPs have demonstrated a significant role in both therapy and imaging of various diseases including cancer. This chapter provides an extensive review of the present status and recent advances in the domain of UCNPs synthesis and their application in theranostics in addition to the upconversion mechanism. Mostly, this chapter deals with challenges associated with the use of UCNP in clinical applications and the strategies to circumvent the associated problems. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023. All rights reserved.