Poloxamers, poloxamines and polymeric micelles: Definition, structure and therapeutic applications in cancer

Research for new therapies to treat diseases like cancer, it is one of the focus of Health Sciences. Nowadays, the available therapeutic strategies have in many cases limitations and undesired side effects, which shows a need to find new therapies with a higher efficacy. In this regard, over the past few years, poloxamers and poloxamines have been gaining more attention in the pharmaceutical field, mainly due to their advantages as potential nanosystems. Therefore, poloxamers and poloxamines are amphiphilic block of copolymers constituted by PEO units, poly(ethylene oxide), and PPO units, poly(propylene oxide), presenting the capability to self-assembly in micellar structures in aqueous medium forming polymeric micelles, which improve theirs potential as drug and genetic material nanocarriers. Thereby, in order to create new alternative treatments for current pathologies, like cancer, alterations in the poloxamines and poloxamers, the combination of these with other polymers and the conjugation with ligands are being introduced as a viable option to allow the combination of therapies, such as the simultaneous delivery of a gene and a drug in the same system. These intelligent stimuli-sensitive systems, with well-defined structures and functionalities, make possible the development of a safe, specific and effective therapeutic strategy. Thus, this article intends to review several aspects of poloxamines and poloxamers concerning their general properties and their applications in drug and gene delivery. Also, are reviewed the preparation and characterization techniques of polymeric micelles with a focus in micelleplexes which can be used as a simultaneous drug and nucleic acid carrier.