- Electroanalysis is performed by differential pulse voltammetry
(DPV) (seeNote 3). - Glass beakers (10 or 5 ml).
- Cleaning the BDD electrode with cyclic voltammetry (CV)
(seeNote 4) is performed using a 50 mM acetate buffer at
pH 5.0 (seeNote 5). A fresh buffer is prepared daily (seeNote6). - The acetate buffer used as the electrolyte solution for the
detection of PYO, HHQ, and PQS: 50 mM acetate buffer
(pH 5.0) consisting of 20 % ACN (seeNote 5). - Control run: Use DPV in the presence of a buffer only (step 5)
without added analytes to ensure that the BDD electrode is
optimized for further measurements (seeNote 7). - Standard run of 5μM PYO, 20μM HHQ, and 20μM PQS:
Use DPV (seeNote 3) in the presence of the analytes in 50 mM
acetate buffer (pH 5.0) consisting of 20 % ACN (seeNote 8)
(Fig.1). - Rinse all three electrodes with DW between runs.
2.2 Sample
Preparation from
Bacterial Cultures
2.2.1 Liquid-Liquid
Extraction (LLE) of Bacterial
Cultures
1.P. aeruginosaPA14 bacterial cultures: PA14 cultures are grown
overnight in LB broth [1 % (wt/vol) bacto-tryptone, 0.5 % (wt/
vol) yeast extract, and 1 % (wt/vol) sodium chloride in distilled
water] at 37C with shaking at 200 rpm. Overnight cultures are
diluted into fresh Luria-Bertani (LB) broth to an absorbance at
600 nm wavelength (A 600 ) of 0.05, and then incubated at 37C
(total volume 20 ml) [17]. Sample aliquots (1 ml) are taken at
different time intervals (e.g., 0, 5, 6, 7, and 8 h).Fig. 3DPV response towards the PA14 strains without (dashed line) and with
CTAB (solid line) which was grown for 7 h. 50 mM acetate buffer pH 5.0
consisting of 20 % ACN was used as an electrolyte for detection on the BDD
electrode vs. Ag/AgCl [15]110 Alyah Buzid et al.