Fig. 2: Sensing performances and mechanism.
From: Two-photon fluorescence imaging and specifically biosensing of norepinephrine on a 100-ms timescale
a Fluorescence spectrum of BPS3 (5 μM) upon addition of NE (0–300 nM), two-photon excited at 720 nm. b Plot and linear fitting of the fluorescence variation rates (ΔF/F0) at 480 nm versus the concentration of NE (0–300 nM). Data are presented as mean ± S.D. Error bars: S.D., n = 3 independent experiments. c Selectivity and (d) competition tests of the probe BPS3 toward NE against other neuron transmitters and amino acids (norepinephrine (NE), epinephrine (EP), dopamine (DA), serotonin (5-HT), γ-aminobutyric acid (GABA), acetylcholine (Ach), cysteine (Cys), homocysteine (Hcy), glutathione (GSH), lysine (Lys), threonine (Thr), serine (Ser)), measured after 10 min of mixing. The concentrations of NE, EP, and DA were 300 nM, and other species were all 1 mM. Data are presented as mean ± S.D. Error bars: S.D., n = 3 independent experiments. e HPLC spectra of (i) NE, (ii) BPS3, (iii) BPS3 reacted with NE, and (iv) BPS3-OH. f HR-MS spectrum of the product of BPS3 reacted with NE in aqueous solution. g The sequential nucleophilic substitution-cyclization mechanism of the reaction between probe BPS3 and NE.
