Chemically Modified Natural Polymer-Based Theranostic Nanomedicines: Are They the Golden Gate toward a de Novo Clinical Approach against Cancer?

It is an unquestionable fact that cancer, also called malignancy, has or will soon become the major global health care problem with an increasing incidence worldwide. Conventional treatment approaches (e.g., radiation or chemotherapy) treat both cancerous and surrounding normal tissues simultaneously, which leads to a poor therapeutic effect on tumors and severe toxic side effects on healthy tissues. Considering these thematic issues, the design and development of more efficient treatment approaches is one of the most important demands of health care in the near future. In this context, the emergence of nanotechnology opens new opportunities for addressing the issues of conventional drug delivery systems (DDSs) for cancer therapy. Theranostic nanomedicines are indebted to the advent of nanotechnology and were introduced by Funkhouser in 2002. These nanomedicines are the newest DDSs that combine diagnostic and therapeutic properties into a single platform. Theranostic nanomedicines are generally composed of targeting agents, diagnostic tracers, effective drug(s), and biomaterial(s) as the matrix to the formulation: Among these, biomaterials have a pivotal role in theranostic nanomedicines due to their direct influence on the system effectiveness. In this context, natural polymers can be considered as potential candidates, mainly due to their inherent physicochemical as well as biological advantages. However, natural polymers have some drawbacks, which can be addressed through the chemical modification approach. In this review, we will highlight the recent progress in the development of theranostic nanomedicines based on chemically modified natural polymers as well as research prospects for the future.