Abstract
Conventional analytical techniques employed for bacteria detection are time consuming (several hours to days). There is an increasing need for the development of rapid and sensitive methods for bacterial detection in clinical diagnosis. In this work, efforts were taken to synthesize graphene based biosensor vancomycin-magnetic graphene oxide (MGOVan) with silica nanoparticles (SiNPs) as biosensors for rapid detection of bacteria. Vancomycin has the capacity of capturing bacteria from aqueous solution. SiNPs were prepared by the Stöber method and then calcining which led to fluorescent. Using fluorescence resonance energy transfer (FRET) from SiNPs to MGOVan, the change in fluorescent intensity offered a novel method for bacteria detection. The lowest detectable bacteria concentration for both S. aureus and E. coli in aqueous solution was about 20 cfu/mL. Further, with unique magnetic feature, MGOVan-bacteria conjugates were aggregated under the external magnet quickly and subjected to matrix assisted laser desorption ionization-time of flight mass spectrometer (MALDI-TOFMS) to distinguish bacteria species. The detectable bacteria concentration for both S. aureus and E. coli by MALDI-TOFMS was about 108 cfu/mL. We also prepared vancomycin and sinapinic acid-magnetic graphene oxide (MGOVanSA). MGOVanSA can enhance bacteria desorption and ionization efficiencies by larger SA ratio in MALDI sample and sample’s sandwich composition. The change in fluorescent intensity and mass spectrometry results demonstrated that MGOVan is an ideal candidate for rapid detection of food and waterborn pathogens.