Branching polymer molecules called dendrimers are being combined with a variety of nanomaterials to form nanohybrids with great promise for light-driven cancer therapy and disease diagnosis. Although the field is currently largely experimental, it holds considerable promise for the future.
“These dendrimer-based materials are now emerging as a hotspot in cancer management research,” says Xiangyang Shi of Donghua University in China, co-author of a review of dendrimer use in photomedicine (light-driven medicine) published in Materials Today Bio.
The term dendrimer derives from dendron, Greek for tree, and dendrimer organic (carbon-based) polymer molecules are roughly spherical structures with complex internal tree-like branching. This provides an excellent scaffold that can incorporate and stabilise other organic molecules and inorganic nanoparticles. Such added materials can be composed of metals or metal-containing compounds, semiconductors and other functional components, including drug molecules.
One of the most promising characteristics of dendrimers in cancer medicine is that they could assist in the diagnosis of disease, helping to identify tumor locations and states of progression, and also in therapy. This combination of diagnosis and therapy is known as theranostics (or sometimes theragnostics).
The review offers a concise summary of the design of several different kinds of dendrimer-based nanohybrids for use in cancer photomedicine. It also covers examples of research that test the potential of specific dendrimers in light-driven therapy, and in imaging molecular indicators of cancer to diagnose and monitor the disease. It then discusses the prospects for future development of the field.
Some dendrimers could assist the diagnosis of cancer by serving as host materials for metal and metal sulfide nanoparticles that can absorb and/or emit light, as well as other forms of electromagnetic radiation, when they are selectively taken up by cancers. This could allow more precise imaging of where a tumor is and how it is changing over time.
When used to deliver treatment, dendrimers can be activated by light to unload therapeutic materials at the precise locations where they are needed. This could protect the body’s healthy tissues from the potentially damaging effects of drugs intended to kill tumor cells. Dendrimers can also improve the solubility and therefore access to cells of therapeutic materials that might otherwise not easily reach and penetrate into the target tissues. The possibilities have so far been investigated only in laboratory tests, sometimes on isolated tissues and cells and in other cases on animal models, but there is clear potential to move towards real clinical applications.
Many researchers are also exploring the option of combining a dendrimer-based approach with other, perhaps more conventional treatments to achieve greater success than either strategy alone.
“There are still challenges to be overcome,” says Shi, citing the need to explore dendrimer modifications that will improve their accumulation at tumor sites and increase their response to applied light.
Shi and his colleagues are themselves actively involved in tackling these challenges. “Moving the field towards further trials in animal models will help to boost cancer nanomedicine and eventually facilitate a smooth translation into clinical practice,” Shi adds.
Article details: Ouyang et al. “Dendrimer-based nanohybrids in cancer photomedicine,” Materials Today Bio (2021)