Nicotine and tyrosine detection in blood and urine samples using taurine/reactive blue-immobilized conducting polymer composite

A sensor for the nicotine (Nic) and L-tyrosine (Tyr) detection was developed with a taurine (Tau) and reactive blue 4 (RB4) bonded-conducting polymer ((poly (2,2´:5´,5″-Terthiophene-3´-p-benzoic acid) (pTBA)) layer formed on AuNPs doped-glassy carbon. The sensing material facilitated a selective electron transfer for Nic and Tyr oxidations and effectively blocked the interferences of negatively charged species by the sulfonate groups and carboxylic acid groups present on the Tau/RB4-pTBA/AuNPs layer. Each layer was characterized employing electrochemical and surface analysis methods. The experimental parameters affecting the sensor response were optimized in terms of amounts of Tau/RB4, pH, temperature, and interference effects. The modified electrode demonstrated excellent performance for the detection of Nic and Tyr in the concentration ranges of 0.02-2.0 and 2.0-300.0 μM and 0.02-5.0 and 5.0-300.0 μM, respectively, with the detection limit (k = 3) of 0.93 ± 0.08 and 0.88 ± 0.06 nM. The reliability of sensor was evaluated by the simultaneous detection of Nic and Tyr in urine and whole blood samples. In addition, the cigarette smoking effect onto the concentrations of target molecules in blood were investigated, where the sensor probe confirms that decrease of Tyr and increase of Nic level by smoking.