One-pot synthesis of hybrid core-shell nanoparticles for antibacterial photodynamic therapy

Multidrug resistance (MDR) in Escherichia coli (E. coli) has become a worrying issue that is not only increasingly observed in humans but also is widespread in veterinary medicine worldwide. Therefore, developing new and e ective alternatives to conventional antibiotics has become an imperative need. The idea of using photodynamic therapy (PDT) for bacterial eradication is a solution for the cases that the bacteria are resisting to conventional antibiotics. Although in these cases, PDT can be an option, PDT-killing efficiency might still not be sufficient, and some enhancements are necessary. Metal-enhanced singlet oxygen generation (ME1O2) is one of the ways to enhance the PDT-killing efficiency of the E. coli. Hybrid core-shell structures can serve conveniently for this purpose. These structures can combine the exible and tailorable features of polymers (shell) with the photophysical properties of plasmonic metals (core). In this work, using gold as a core and conjugated oligomer as a shell produced a novel hybrid core-shell nanoparticles which can enhance the singlet oxygen generation capacity and subsequently, improve the PDT-killing efficiency of the E. coli. In this structure, the shell is responsible for the spontaneous reduction of gold ions, forming gold nanoparticles and protecting them from the aggregation. With further investigation and optimization, the hybrid core-shell nanoparticles with the help of ME1O2 successfully improved the killing efficiency of E. coli bacteria by 40%.