Fig. 2: NIR fluorescent nanosensors of virulence factors.
From: Remote near infrared identification of pathogens with multiplexed nanosensors
a Design of an endotoxin sensor for bacterial lipopolysaccharides (LPS). NH2-(GT)20-ssDNA colloidally stabilizes the SWCNTs and was linked to a LPS-binding peptide via SMCC (succinimidyl 4-(N-maleimidomethyl) cyclohexane-1-carboxylate) chemistry. b NIR fluorescence increase of bindLPS-(bLPS)-SWCNTs after addition of 25 µM E. coli LPS. c Dose–response curve of bLPS sensors for LPS from E. coli, K. pneumoniae, P. aeruginosa and Salmonella spp. (n = 3 independent experiments, mean ± SD). d Design of the siderophore sensor. An aptamer (HeApta) binds hemin, which brings Fe3+ into the proximity of the SWCNT and quenches it. Siderophores can reverse this effect by removing iron (Fe3+), which increases fluorescence again. e Exemplary spectra of HeApta-SWCNTs. Addition of hemin (I0 to I1) quenches their fluorescence and addition of siderophores (pyoverdine) increases it again (I1 to I2). f Calibration of chelating agents with different stability constants (Kf) for iron (Fe3+), added to HeApta-SWCNTs with 1 µM hemin concentration. Pyoverdine (Kf = 1032), deferoxamine (Kf = 1030), EDTA (Kf = 1025), hemin (Kf = 1022), citrate (Kf = 1012)78,89,90,91 (n = 3 independent experiments, mean ± SD).
