Screen-printed carbon electrode modified with de-bundled single-walled carbon nanotubes for voltammetric determination of norepinephrine in ex vivo rat tissue.

A voltammetric sensor for norepinephrine (NE) detection was developed by modifying a disposable screen-printed carbon electrode (SPCE) with de-bundled single-walled carbon nanotubes (D-SWCNTs). The de-bundling was carried out using a newly synthesized polymeric dispersant, a co-polymer of polystyrene sulfonate and methacrylate of lipoic acid. The D-SWCNTs/SPCE showed better sensitivity towards NE compared to the bare SPCE and that modified with bundled SWCNTs. The sensor was optimized for detecting NE by differential pulse voltammetry (DPV) in terms of the D-SWCNTs concentration, DPV parameters, and solution pH. Under the optimum conditions, the sensor exhibited a dynamic linear range of 100 nM-2.0 µM NE, and the detection limit was 62.0 nM (S/N = 3). Additionally, the effects of possible interferents were investigated. The relative standard deviation for five successive measurements of 2.0 µM NE was 7.6%, and approximately 75.8% of the sensor activity was retained after four weeks of storage. The practical potential of this sensor was demonstrated by quantifying NE in ex vivo rat tissue samples.