Down-Regulation of HSP by Pd-Cu Nanozymes for NIR Light Triggered Mild-Temperature Photothermal Therapy Against Wound Bacterial Infection: In vitro and in vivo Assessments

Abstract

Yan Zhou,1,2,* Zekun Zhou,3,* Xiaojuan Wu,2 Zefeng Wang,2 Wangdan Qi,1 Jing Yang,1 Liming Qing,3 Juyu Tang,3 Le Deng1 1State Key Laboratory of Developmental Biology of Freshwater Fish, Department of Microbiology, College of Life Science, Hunan Normal University, Changsha, Hunan, People’s Republic of China; 2State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Hunan University, Key Laboratory for Bio-Nanotechnology and Molecule Engineering of Hunan Province, Changsha, Hunan, People’s Republic of China; 3Department of Orthopedics, Hand and Microsurgery, Xiangya Hospital of Central South University, Changsha, Hunan, People’s Republic of China*These authors contributed equally to this workCorrespondence: Le Deng, State Key Laboratory of Developmental Biology of Freshwater Fish, Department of Microbiology, College of Life Science, Hunan Normal University, Changsha, Hunan, People’s Republic of China, Email [email protected] Juyu Tang, Department of Orthopedics, Hand and Microsurgery, Xiangya Hospital of Central South University, Changsha, Hunan, People’s Republic of China, Email [email protected]: We aimed to develop an oxidative-stress-activated palladium-copper nanozyme to reduce bacterial’s heat sensitivity by down-regulating heat shock proteins to overcome the shortcomings of conventional photothermal antimicrobial therapy and achieve mild photothermal bactericidal efficacy.Methods: We first synthesized palladium-copper nanozymes (PC-NPs) by hydration and used transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy to demonstrate their successful preparation. Their photothermal therapy (PTT) and chemo-dynamic therapy (CDT) activities were then determined by a series of photothermal performance tests and peroxidase-like performance tests, and the destruction of heat shock proteins by reactive oxygen species (ROS) was verified at the protein level by Western Blotting tests, providing a basis for the effective bacteria-killing by the mild-temperature photothermal treatment subsequently applied. We also validated this promising programmed and controlled antimicrobial treatment with palladium-copper nanozymes by in vivo/in vitro antimicrobial assays. A hemolysis assay, MTT cytotoxicity test and histopathological analysis were also performed to assess the in vivo safety of PC-NPs.Results: In the micro-acidic environment of bacterial infection, PC-NPs showed peroxidase-like activity that broke down the H2O2 at the wound into hydroxyl radicals and down-regulated bacterial heat shock proteins. The application of PC-NPs increased bacteria’s sensitivity to subsequent photothermal treatment, enabling the elimination of bacteria via mild photothermal treatment.Conclusion: The programmed synergistic catalytic enhancement of CDT and mild photothermal therapy achieves the most efficient killing of bacteria and their biofilms, which brings future thinking in the relationship between heat shock proteins and oxidative stress damage in bacteria.Keywords: nanozyme, mild-temperature photothermal therapy, DnaK, reactive oxygen species, ROS, antibiofilm

Keywords

• nanozyme
• mild-temperature photothermal therapy
• dnak
• reactive oxygen species
• ros
• antibiofilm