Upconversion nano-particles from synthesis to cancer treatment: A review

Among many methods to fabricate drugs, Upconversion seems to be an appropriate approach in order to treat cancer with almost no side effects. Upconversion is able to effectively convert two or more low energy photons into the higher energy photons. Since the traditional process of the drug circulation in the biological environment leaves the individuals with many side effects, the translation of the drug to the tumor site is one of the imperative concerns. Because of the capability of the light source in the activation of the fabricated drug in the upconversion process, the photodynamic therapy has attracted a wide range of researchers. There are some approaches to overcome the side effects of cancer therapy. One of the most efficient approaches is the fabrication of biomaterials in the form of micro or nano-capsules. In the upconversion method, it is possible to fabricate a core-shell complex to achieve better yield. In this method, drug can be encapsulated into the core with the size of nano or micro. The structure of the shell in this complex is usually sensitive to the internal or external stimuli as pH or temperature difference. Subsequently, the shell structure would be damaged due to this sensitivity and finally the drug can be released from the core into the targeted site. Moreover, there is an immense interest to develop cancer therapy in the form of the combination therapy which is employing drugs with different working mechanisms and diminishing the probability that resistant cancer cells will grow. In summary, this review article firstly introduces the main methods of the fabrication of upconversion nanoparticles. Then, the application of these particles in different types of cancer therapy including combined therapy is discussed. Moreover, the main drugs applicable in the cancer therapy and their effects in the fabrication of upconversion nanoparticles and complexes are presented. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.