1. Correlation between Nyquist plots for: (A) bare GCE and (B) SWCNT+PEI+HRP modified GCE in 10 mM K 3 [Fe(CN) 6 ] + K 4 [Fe(CN) 6 ], in phosphate buffer (0.1 M; pH 7.4). Amplitude: 10 mV, first frq 100 kHz last frq 10 mHz. Fitting results are given by lines. Inset: the equivalent circuits used. Nanomaterials Based Sensors for Acetaminophen and Dopamine Detection Luminiţa Fritea, Cecilia Cristea, Mihaela Tertiş, Oana Hosu, Robert Săndulescu Analytical Chemistry Department, Faculty of Pharmacy, “Iuliu Haţieganu” University of Medicine and Pharmacy, Pasteur 4 Cluj-Napoca, Romania, rsandulescu@umfcluj.ro CONCLUSIONS The combination of different types of nanomaterials (CNTs, graphenes, cyclodextrins) and polymers as immobilization platform with different bioreceptors reveals enhanced electroanalytical performances of the sensors in the pharmaceutical and biomedical analysis. The obtained biosensors present good sensitivity and selectivity for the detection of various pharmaceuticals. Amperometric response for dopamine on β-CD+PPO+PEI- GO/GCE (a) and bare GCE (b); tyrosinase concentration: 1 mg/mL; PEI 1mg/mL; LOD: 10.42 μM LDR: 30-2500 μM A. Acetaminophen biosensor based on carbon nanotubes and horseradish peroxidase (HRP) This paper was elaborated under the frame of European Social Found, Human Resources Development Operational Programme 2007-2013, projects no. POSDRU/159/1.5/S/138776 and 159/1.5/S/136893. The authors are grateful for the financial support to the Romanian National Authority for Scientific Research, CNCS - UEFISCDI, project number PN-II-ID-PCE-2011-3-0355. Amperometric response for acetaminophen on GCE (d=1 mm) modified with HRP/SWCNT/PEI film; HRP concentration: 0.3 mg mL -1 and 0.6 mg mL -1 in PEI 1 mg mL -1 (A) SWVs registered on: bare GCE (a); PPO(1mg/ml)+PEI(1mg/ml) (1 layer) modified GCE (b); β-CD (1mg/ml) (1 layer) + PPO + PEI (1 layer)/GCE (c); PPO+ PEI (1 layer) GO (LBL; 3 layers)/GCE (d); β-CD (1 layer) + PPO + PEI (1 layer) g GO (LBL; 3 layers)/GCE (e) in the presence of 1 mM dopamine solution in PB solution (0.1M; pH 7.2). (B) EIS spectra (61 frq. 100kHz -10 mHz; amplitude: 0.01 V) registered for: bare GCE (a); and modified with: graphene oxide (GO) by spin coating (b); GO through layer by layer deposition - 3 layers (c) and GCE modified with GO through LBL deposition and β-CD (d) in the presence of 10 mM [Fe(CN) 6 ] 3-/4- in PBS (0.1 M; pH 7.2); B. Dopamine biosensor with graphene and tyrosinase (PPO) o Schematic representation for the development of acetaminophen and dopamine biosensors o Real sample analysis – acetaminophen determination in pharmaceutical products (A)(B) (D) (E) (B) (A) o Biosensor testing - amperometry LOD: 1.36–8.09 μM LDR: 4 - 80 μM; 20 - 160 μM (A) (B) o Electrochemical characterization of modified glassy carbon electrodes and biosensors optimization Different types of electrochemical biosensors are reported based on nanomaterials like carbon nanotubes (SWCNT), graphenes, cyclodextrines (β-CD) and conductive polymers (polyethylenimine - PEI). Two model molecules, acetaminophen and dopamine were detected with those biosensors. Electrode typePharmaceutical samples Samples acetaminophen concentration (μM) Added (μM) Found (μM) Recovery (%) RSD (%) 0.3mg HRP/mlPEI /SWCNT(15layer)/GCE PANADOL 500 mg (GlaxoSmithKline) 10 - 10 20 10.04 20.88 31.09 100.40 104.40 103.64 1.67 1.31 2.04 SANADOR 500 mg (S.C.Laropharm S.R.L.) 10 - 10 20 9.94 19.77 28.97 99.44 98.85 96.60 2.35 2.54 2.09 0.6mg HRP/mlPEI /SWCNT(15layer)/GCE PANADOL 500 mg (GlaxoSmithKline) 10 - 10 20 9.97 18.04 26.89 99.70 90.02 89.64 1.97 2.43 2.56 SANADOR 500 mg (S.C.Laropharm S.R.L.) 10 - 10 20 9.89 18.66 28.24 98.90 93.32 94.15 1.05 1.64 1.87 Measurement results for acetaminophen in pharmaceutical samples AcetaminophenDopamine The acetaminophen indirect detection mechanism – catalytic peroxydation through HRP