https://phys.org/news/2018-10-nanomaterials-cancer-specific-stimuli-delivery-treatments.html

Nanomaterials are being designed to specifically target tumours by responding to unique tumour conditions, such as acidity and over-expressed enzymes, explain the reviewers from Xiamen University in China.

Acidity levels normally vary between tissue types, and tumours are usually more acidic than the surrounding healthy tissue. Researchers are using this to design delivery vehicles from organic, inorganic and hybrid nanomaterials that release their contents in response to tumours' acidic environment. For example, acid-sensitive polymers have been explored for delivering the chemotherapeutic drug doxorubicin coupled with a fluorescent compound. When the system reaches its target, it is taken up by tumour cells and is exposed to their acidic environment. The polymer then changes its shape in a way that releases its contents, allowing both the treatment and imaging of the cancerous cells.