An electrochemical chiral sensing platform for propranolol enantiomers based on size-controlled gold nanocomposite

The size-controlled gold nanoparticle-methylene blue-multiwalled carbon nanotubes nanocomposite (nanoAu-MB-MWNTs) was successfully synthesized as electrochemical redox-probe indicator and immobilization matrix, which calf thymus double-stranded DNA (ctDNA) could be adsorbed for chiral sensing propranolol (PRO) enantiomers. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and ultraviolet-visible spectroscopy (UV-vis) were used to characterize the functionalized nanocomposite. The DNA-immobilized sensing platform (ctDNA/nanoAu-MB-MWNTs/GCE) showed a larger electrochemical response for S-PRO than R-PRO, in which the association constant (p) was calculated to be 1.154 x 10(4) L mol(-1) for S-PRO and 4.638 x 10(3) Lmol(-1) for R-PRO. Quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS) had confirmed the higher affinity for S-PRO with ctDNA. The experimental parameters such as acidity, incubation time, size of nanoAu and the amount of ctDNA were assessed to obtain the optimized conditions. Moreover, the proposed sensor was applied to determine the enantiomeric ratios of R-PRO in mixture solutions and high-performance liquid chromatography (HPLC) was used to validate the results by calculating F- and t-test values at 95% confidence level. (C) 2014 Elsevier B.V. All rights reserved.