As a minimally invasive method for cancer therapy at precise locations, NIR-induced photothermal therapy (PTT) has drawn extensive attention.

The therapeutic mechanism is the use of photothermal agents (PTAs) in the treatment of tumours and its therapeutic effect happens only at the tumour site where both light-absorbent and localised laser radiation coexist.

The development of PTAs with NIR-II absorbance, ranging from 1000 nm to 1700 nm, can efficiently improve their penetrating ability and therapeutic effects because of their high penetration depth in the body.

However, several disadvantages are associated with these NIR-II responsive PTAs for their use in biomedical areas. Magnetic nanoparticles (MNPs), which boast strong absorption effect in NIR-II, can meet this demand.

It has attracted much attention for biomedical applications with its non-invasive imaging function and magnetic-induced targeted ability.

Recently, a research team led by Prof. WANG Hui and Prof. LIN Wenchu of High Magnetic Field Laboratory, Hefei Institutes of Physical Science (HFIPS), the Chinese Academy of Sciences (CAS) reported a new type of NIR-II responsive hollow magnetite nanoclusters (HMNCs), which is made of composed of Fe3O4, mesoporous shell and hollow cavity for targeted imaging-guided combined therapy of cancer.

"HMNC absorbed NIR-II laser and converted it into local heat," said Prof. WANG, "therefore we successfully accelerated combination of drug release and chemo-photothermal therapy."

In one-step solvothermal method, they prepared HMNCs with NIR-II absorption at 1066 nm under an external magnetic field (0.5T), which provided photothermal effect on tumour.

Besides, as Fe3O4 dissolved in the acid environment, they can convert H2O2 into toxic Hydroxyl radicals, which add chemo-dynamic effect.

What's more, the hollow cavities in HMNCs are good loading places for drug, which also acted as a targeted contrast agent for tumour magnetic resonance imaging.

Further in vivo experiments proved that the combined effect of photothermal, chemo-therapy and chemo-dynamic therapy of HMNCs has a significant inhibitory effect on mouse tumour growth.

This experiment showed a kind of multifunctional nanocarriers based on NIR-II responsive HMNCs for trimodal cancer therapy.

Source: Hefei Institutes of Physical Sciences