Fabrication of Polymer Brush/Silver Nanoparticle Nanocomposite as Surface Enhanced Raman Scattering Substrate for Detection of Quorum Sensing Signal Molecule

Quorum sensing (QS) is a intercellular communication phenomenon among most bacteria which allows bacteria to monitor and respond their local environment and population density by secreting and sensing certain signal molecules. Pseudomonas aeruginosa (PAE) is one of main opportunistic pathogenic bacteria for wound infection and strong resistance to antibiotics because of the formation of biofilm. Recently, some research groups have reported that the formation of PAE biofilm is mainly controlled by QS mechanism, which relies on the release and recognition of specific low molecular weight molecules (so. called quorum sensing signal molecule, QSSM). Therefore, it is desirable to develop a rapid and sensitive method for the detection of both PAE and its corresponding QSSM to improve the cure of wound infections. In this work, poly(oligo (ethylene glycol) methacrylate) (POEGMA) brushes on Si wafer were prepared by atomic transfer radical polymerization technique (ATRP), which were then employed as matrix for the loading of silver nanoparticles (AgNP) by repeating the immersion. rinsing. drying steps, giving rise to a POEGMA/AgNP nanocomposite SERS substrate. Scanning electron microscopy (SEM) and UV-Visible spectroscopy measurements clearly indicated the 3D distribution of AgNPs within the POEGMA brush. The resulting SERS substrates were then used for the detection of PAE and two typical QSSMs: pyocyanin (PCN) and N-dodecanoyl-homoserine lactone (C12-HSL). Raman measurements suggested that the detection limit of the current SERS substrate for PCN, C12-HSL and PAE was 10(-10) mol/L, 10(-8) mol/L and 10 CFU/mL, respectively. Considering the merits associated with SERS technique, such as label-free, highly sensitive and low interference from water, the current POEGMA/AgNP nanocomposite SERS substrate is highly potential for the future investigation of PAE's quorum sensing phenomenon.