Polymeric Nanocarriers in Cancer Theranostics

Abstract

Conventional chemotherapy using small molecules as antitumoral agents exhibited clinical limitations, related to serious side effects generated by the low selectivity toward tumor cells, since they also act on healthy tissues. Theranostics is a new field of nanomedicine, combining therapy, diagnosis, and real-time monitoring using imaging techniques. It is useful to monitor the biodistribution of the chemotherapeutic agent that can be activated in the target site to exert its action only in cancerous tissue. When theranostics and nanocarriers are associated, active tumor targeting can be more effectively obtained allowing in vivo tracking using imaging techniques for cancer treatment. The active molecule can be a photosensitizer physically associated or covalently conjugated with the nanocarrier, where the probe shows absorption in the near-infrared spectra. This activation generates free radicals, in photodynamic therapy, and/or heat, in the photothermal therapy, leading to cell death in the target tissue. Polymeric nanoparticles play a major role in this field because they are versatile and stable in biological fluids and they can be more easily conjugated with different types of organic or inorganic probes. The main focus of this chapter is on the polymeric nanoparticles that were developed and applied to act against cancer cells in vitro and in vivo using the nanotheranostic approaches. We expect that this chapter can give the first insights as to how a polymeric nanocarrier could be applied as a theranostic agent for tumor treatment, contributing to a more selective strategy to reduce the adverse effects. Promising in vivo results have been reported and discussed in the context of their biological applications.