Combination of Nanomaterials and Bacteria for Tumor Treatment

Abstract

Nowadays malignant tumors are still one of the disastrous diseases. It is necessary to explore new strategies for the treatment of malignant tumor. Nanomaterials refer to materials with at least one dimension of the three dimensions in the nanometer range (1~100 nm). They show a wide range of applications in tumor treatment while disadvantages of low targeting efficiency, poor tumor penetration and obvious side effects still limit their applications. As a method for tumor treatment, bacterial therapy has a long history. Some facultative anaerobic and obligate anaerobic bacteria and their secretions have the characteristics of targeting hypoxic tumor tissue, strong tumor penetration and stimulating immune responses. After genetically modification or attenuation treatment, it can be used for tumor treatment. However, the safety issues and low therapeutic efficiency still needs to be solved. The combination of nanomaterials and bacteria can complement the limitation of each other, and shows great potential in tumor therapy. On one hand, bacteria could enhance the targeting efficiency of nanomaterials, and decrease the side effects. On the other hand, nanomaterials could help improve the safety and solve the problem of low therapeutic efficiency of bacterial therapy. In this review, the combination of nanomaterials and bacteria is divided into three categories based on the role of bacteria in the treatment. Firstly, the preparation of composites of nanomaterials and bacteria by chemical bonds, electrostatic interaction, and other ways to enhance tumor targeting. Secondly, bacterial enzyme could react with nanomaterials to control the release of drug. Thirdly, secretions of bacteria after plasmids were introduced and outer membrane vesicles secreted by bacteria could be combined with nanomaterials for anti-tumor therapy. The mechanisms of the combination therapy are also discussed. Finally, we summarized and discussed the current challenges, especially the safety of the combination therapy. The prospect of the combination of nanomaterials and bacterial for tumor treatment is also proposed.