Dynamic monitoring of bacteriostatic process by SERS analysis based on a simple but effective detection strategy

Investigating antibacterial process at a molecular level is helpful to fully understand the mechanism of bacteriostasis and develop new antimicrobial agents. Herein, a simple but effective sensor strategy of antibacterial nanocomposite combined with surface-enhanced Raman scattering (SERS) substrate was applied for the robust detection of bacteriostatic process. The synergistic SERS effect of nanocomposite and Ag nanoparticles (NPs) substrate was confirmed by finite difference time domain (FDTD) solutions. A curcumin liposome@Au NPs nanocomposite was designed and prepared as a kind of bacteriostatic agent and SERS material as well. By means of electrostatic attraction between the nanocomposite and bacteria (methicillin resistant staphylococcus aureus, MRSA), specific detection of MRSA and monitoring of the molecular structure changes after bacteriostaticeffect were realized by SERS. Important intermediates produced in the bacteriostatic process were also measured at the same time. The relationship between the relative peak intensities and the structure of MRSA were thus established. The results were verified by high performance liquid chromatography-mass spectrometry (HPLC-MS), reactive oxygen species (ROS) kit, and flow cytometry. The detection strategy we proposed could not only be used for real-time detection of bacteriostatic processes with a high efficiency, but also a powerful tool for analyzing the mechanism in biochemical processes.