Studies have shown that facultative anaerobic bacteria and obligate anaerobic bacteria can target hypoxic tumor areas because of their hypoxic tendency. In addition, some bacteria have evolved the ability to reduce metal minerals to metal elements in adversity, which is used for respiratory metabolism. Many photothermal agents are simple metals, so the characteristics of bacteria can be used to develop photothermal bacteria from mineralized photothermal agents on the surface of bacteria, and have good tumor targeting performance. It is well known that the heat tolerance of tumors is regulated by heat shock proteins (HSPs), and the expression of HSPs requires ATP to supply energy. Therefore, damage to mitochondria by disrupting the mitochondrial redox balance can reduce ATP synthesis and inhibit the expression of HSPs. In view of this, they used S.  oneidensis  MR-1 bacteria to reduce the palladium salt (Na 2 PdCl 4 ) to synthesize the photothermal bacteria loaded with palladium on the surface of the bacteria. The bacteria have good photothermal properties and tumor targeting effects. They further synthesized MOFs (ZIF-90 / MB) containing methylene blue, which can be specifically degraded by ATP in mitochondria to release methylene blue. The released methylene blue generates singlet oxygen to damage the mitochondria by light, thereby achieving the effect of inhibiting ATP production and HSPs expression. Finally, the MOFs are modified on the surface of the synthetic photothermal bacteria through acid-sensitive imine bonds to improve the photothermal treatment of tumors.

The bio-hybrid material does not affect the bacterial activity during the synthesis process, shows good tumor targeting performance and significant tumor photothermal treatment effect, and effectively solves the poor targeting performance of photothermal agents and tumor heat resistance in tumor photothermal treatment The shortcomings provided have provided a feasible strategy for the further development of photothermal therapy and opened up a new path for the application of bacteria in tumor therapy.

Self-Mineralized Photothermal Bacteria Hybridizing with Mitochondria-Targeted Metal--Organic Frameworks for Augmenting Photothermal Tumor Therapy Qi-Wen Chen, Xin-Hua Liu, Jin-Xuan Fan, Si-Yuan Peng, Jia-Wei Wang, Xia-Nan Wang, Cheng Zhang, Chuan-Jun Liu, Xian-Zheng Zhang Adv. Funct. Mater .,  2020 ,  30 , 1909806, DOI: 10.1002 / adfm.201909806

Source of information: X-MOL Information