Gold nanoparticles-mediated fluorescent chemical nose sensor for pathogenic diagnosis and phenotype

Pathogens are one of the important factors affecting national economic construction. An ideal detection system for pathogen control with excellent sensitivity, high specificity, and time-saving is needed. Here, we reported a method for bacterial detection using gold nanoparticles-mediated fluorescent "chemical nose" sensors (GFCEs). The technique consists of gold nanoparticles-coated magnetic particle using benzaldehyde, octyl aldehyde, and pyrimidine-4-formaldehyde modified, respectively. And these positively charged nanocompound interacting with three different fluorescent proteins (FPs) to form three kinds of GFCEs, respectively, named GFCE1, GFCE2, and GFCE3. Upon binding with pathogenic cells, functionalized gold nanoparticles could identify patches on hydrophobic/functional surfaces of microorganisms, and self-assemble with living bacteria by complementary electrostatic interactions. The binding ability between GFCEs and bacteria determines the change of fluorescence response of three FPs from GFCEs. These feature fluorescent level are pathogen-specific, highly repeatable, and can be analyzed by Linear Discriminant Analysis (LDA). The combination of GFCE1 and GFCE2 has the best performance when detecting pathogens with concentrations of 10⁶  cfu mL^-1 . The first discriminant within 15 minutes is 93.8%, which could be used for subsequent identification of unknown samples. The commonly applicable system provides a simple way for the rapid bacterial detection without preprocessing procedures.