Multiple enzyme-mimic polypeptide based carbon nanoparticles by ROP and Fe coordination for ROS regulation and photo-thermal therapy against bacterial infection.

Novel strategy is urgently needed to overcome the bacterial infection all over the world due to unreasonable use of biotics. In recent years, nanozymes have attracted great interests of researchers for their high catalytic efficiency and biocompatibility. In this study, a novel multiple enzyme-mimic polypeptide-based carbon nanoparticle was synthesized by N-carboxyanhydride mediated ring opening polymerization (ROP) and Fe coordination for actualizing ROS regulation and photo-thermal therapy. The multiple enzyme-mimic activities of the nanozyme, such as peroxidase, oxidase, catalase, and glutathione peroxidase, were detailly explored in ROS regulation for potential utilization in bacterial inhibition. The photo-thermal effect of the nanozyme was investigated under 808 nm NIR irradiation. Enhanced inhibition rate of the as prepared nanozyme was observed against Gram-negative Escherichia coli (99.03 %) and Gram positive Staphylococcus aureus (99.78 %) planktonic bacteria. Methicillin-resistant Staphylococcus aureus (MRSA) was chosen as the drug resistant bacteria model to evaluate the efficiency in bacterial biofilm disruption. Improved healing efficacy of 99.05 % against MRSA wound infection and excellent biosafety were observed in mice model experiments for the as prepared nanozyme. In conclusion, the as synthesized nanozyme with ROS regulation, enhanced bacteria inhibition, and excellent biocompatibility could be potentially applied in clinic against bacterial infection.

Poly-l-lysine modified MOF nanoparticles with pH/ROS sensitive CIP release and CUR triggered photodynamic therapy against drug-resistant bacterial infection.

The challenge of drug resistance in bacteria caused by the over use of biotics is increasing during the therapy process, which has attracted great attentions of the clinicians and scientists around the world. Recently, photodynamic therapy (PDT) triggered by photosensitizer (PS) has become a promising treatment method because of its high efficacy, easy operation, and low side effect. Herein, the poly-l-lysine (PLL) modified metal-organic framework (MOF) nanoparticles, ZIF/PLL-CIP/CUR, were synthesized to allow both reactive oxygen species (ROS) responsive drug release and photodynamic effect for synergistic therapy against drug resistant bacterial infections. The PLL was modified on the shell of the zeolite imidazole framework (ZIF) by the ROS-responsive thioketal linker for controllable CIP release. CUR were encapsulated in ZIF as the photosensitizer for blue light mediated photodynamic effect to produce singlet oxygen (1O2) and superoxide anion radical (O2-) for efficient inhibition towards methicillin-resistant Staphylococcus aureus (MRSA). The charge conversion from negative charge (-4.6 mV) to positive charge (2.6 mV) was observed at pH 7.4 and pH 5.5, and 70.9 % CIP was found released at pH 5.5 in the presence of H2O2, which suggests the good biosafety at physiological pH and ROS-responsive drug release of the as-prepared nanoparticle in the bacterial microenvironment. The as-prepared nanoparticles could effectively kill MRSA and disrupt bacterial biofilm by combination of chemo- and photodynamic therapy. In mice model, the as-prepared nanoparticles exhibited excellent biosafety and synergistic effect with 98.81 % healing rate in treatment of MRSA infection, which is considered as a promising candidate in combating drug resistant bacterial infection.