Fig. 2
Schematic representation of the plasmonic nose sensor design. a Sensor strip containing seven “olfactory receptors” with distinct nanoparticle morphology: i GNB, ii GNSph, iii GNR670, iv GNR730, v GNSht680, vi GNSht700, and vii GNStr. Each nanoparticle morphology is embedded in agarose and mixed with Tollens’ reagent, 2[Ag(NH3)2]OH. b During the detection test, a suspension of bacteria in King´s B culture media is loaded in the microtube, and then the sensor cap is placed in the tube. c During bacteria metabolism, if some volatile aldehydes and ketones are released to the headspace of the tube, these molecules will reduce the Tollens’ reagent, and metallic Ag will be deposited on the AuNP of the sensor, inducing a plasmon change that can be visualized in a color change of the sensor. d The color changes are analyzed with a MatLab algorithm designed in this work to obtain the ΔRGB for further chemometric analysis