Supplementary Information (ESI)

Fabrication and characterization of poly-2-Napthol orange film modified electrode and its application to selective detection of Dopamine

Ramalingam Manikandan,P.N Deepa and Sangilimuthu Sriman Narayanan*

Department of Analytical chemistry, School of chemical Sciences,

University of Madras, Guindy campus, Chenai-600 025, India.

Fig.S1 Poly 2-napthol orange film modified electrode at different pH condition (4-9)

Inset figure shows pH vs. current plot and pH vs. Epa

Fig. S2 Cyclic voltammogram of A-bare electrode and B- 2-napthol orange film modified electrode in 0.1 M KNO3 containing K4[Fe(CN)6]3-/4- as background electrolyte at scan rate of 50 mV s-1.

Fig.S3 Cyclic voltammogram of 13 µM DA at A-bare (without DA) B- bare electrode with DA and C-pretreated electrode with DA in 0.1 M phosphate buffer(pH-7). Scan rate 50 mV s-1.

Fig.S4 CV of Poly 2-napthol orange in 0.1 M phosphate buffer (pH-7) at scan rate of 50 mV s-1

Fig.S5 A- CV of different concentration of DA in 0.1 M phosphate buffer (pH-7)

Scan rate of 50 mV s-1 and B- Calibration plot.

Fig.S6A- Effect of pH for dopamine oxidation current and B- Plot of pH vs. potential shift

Fig.S7 Hydrodynamic voltammeric response of A- bare electrode, B- Bare electrode in the presence of DA, C – poly 2-napthol orange film modified electrode and D- poly 2-napthol orange film in the presence of DA in 0.1 M phosphate buffer (pH-7) under string condition 300 rpm.

Fig.S8 Chronoamperometric response of poly 2-napthol orange film modified electrode with

200 µL addition of DA in 0.1 M phosphate buffer (pH-7) under string condition 300 rpm

Inset diagram is calibration plot.

Fig.S9 The current response at P2NO film modified electrode towadrs 30 μM of DA detection over 60 days of storage. Inset current response at P2NO film modified electrode for 30 μM of DA vs. time (mins), supporting electrolyte-0.1 M PBS at scan rate of 50 mV s-1

Fig.S10 Interference study of 2-napthol orange film modified electrode.

  1. DA- Dopamine,
  2. UA- Uric acid,
  3. AA- Ascorbic acid,
  4. Cys- Cystiene,
  5. CA- Citric acid,
  6. Tyr-Tyrosine,
  7. Glu-Glucose

Scheme-A Mechanism of the poly-2-napthol orange electrode reaction

Table-1S Comparison of some proposed electrode for DA determination in the presence of AA and UA. The materials used for the modification and the procedures required are also shown.

Electrode modified material Procedure for modification Ref

GCEPoly(orthanilic acid)-multiwalled carbon 1.Synthesis of PABS, 2. Acid functionalization of the MWCNT’s

nanotubes (PABS-MWCNT) 3.Modification of the GCE by dropping MWCNT suspension 1

Directly on to the GCE surface. 4. Immersion of the MWCNT’s

Modified GCE into ABS.

GCEMethylene blue absorbed onto multi walled 1. Acid functionalization of the MWCNT’s. 2. Dispersion of the Carbon nanotubes (MB-MWCNT’s) MWCNT’s in MB aqoues solution and sonicated for an 3hour

3.Preparation of a MB-MWCNT’s suspensions in Nafion-methanol 2

Solution by 30min sonication. 4. GCE is coated with MB-MWCNT’s

Suspension with methanol evaporation at room temperature.

GCECombination of incorporated Nafion1. Sonication of the GCE in a mixture of water/ethanol.

Singled walled carbon nanotubes and poly2. Polymerization of MT on the GCE (PMT/GCE) by potential

(3-methylthiophene) (PMT) filmstep 1.75 V (vs.Ag/AgCl), for 20 s in a solution containing 0.1 M

MT and 0.1 M terrabutyl ammonium perchlorate (dissolved in CH3CN)

3. Nafion solution was scrupulously dropped onto the PMT/GCE

Surface; the solvent was evaporated in air to obtain NF/PMT/GCE

4. Singled walled carbon nanotube (SWCNT’s) dispersion was

Scrupulously dropped on to the surface of PMT/GCE then the 3

Solvent was evaporated in air to obtain NF/SWCNT’s/PMT/GCE

GCEOveroxidaised dopamine polymer1.The pretreated GCE was dipped into 0.05M DA solution containing

and 3,4,9,10-perylenetetra carboxylic0.10M SDS to perform electro polymerization of dopamine through 6 4

acidsuccessive potential sweep between -0.60 and 0.80 V at 100mVs-1, and then transferred to 0.10M PBS (pH-3.0) for electrochemical oxidationat

+ 1.8V for 250s.2. The modified electrode then 10µL of PTCA suspension

was dropped on the electrode surface.

GCEPoly (Tyr)/MWCNTs-COOH1. The MWCNTs prepared by dispersing 1.0 mg MWCNTs – COOH in

10mL DMF under sonication for 30min. 2. A 10µL aliquot of black 5

suspension is dropped directly on the electrode surface and it was dried

in room temperature. 3. The PBS (pH-6) containing 1mM of tyrosine

is polymerized under potential cycling between -0.8 to 1.8 V at scan rate of

100mV s-1 for 16 cycles.

GCEPoly (pyrocatacol violet)/ MWCNTs1. The MWCNTs prepared by dispersing 1.0 mg MWCNTs – COOH in

10mL DMF under sonication for 30min. 2. A 10µL aliquot of black 6

suspension is dropped directly on the electrode surface and it was dried

in room temperature. 3. The obtained electrode was taken as MWCNTs– COOH/GCE. The poly (PCV)/MWCNTs–COOH/GCE was prepared by

electropolymerization. The polymertic film was deposited on MWCNTs

–COOH/GCE by cyclic sweeping from −1.5 to 1.5 V at 100 mV s−1 for fifteen

cycles in pH9.2 phosphate buffer solution containing 1.0 × 10−3 mol L−1 PCV.

After polymerization, the modified electrode was washed with doubly distilled water,
and then air-dried.

PIGEPoly 2-Napthol orange 1.Polymerization of 1mM 2-napthol orange on the PIG electrode at 30 this work

segments , the poly 2-napthol orange was formed

References

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  2. Yang S, Li G, Yang R, Xia M, Qu L (2011) Simultaneous voltammetric detection of dopamine and uric acid in the presence of high concentration of ascorbic acid using multi-walled carbon nanotubes with methylene blue composite film-modified electrode.J Solid State Electrochem15:1909-1918
  3. Dai Lam T, Tram PTN, Binh NH, Viet PH (2011) Electrochemically selective determination of dopamine in the presence of ascorbic and uric acids on the surface of the modified Nafion/single wall carbon nanotube/poly (3-methylthiophene) glassy carbon electrodes.Colloids and Surfaces B: Biointerfaces88:764-770
  4. Liu X, Ou X, Lu Q, Zhang J, Chen S, Wei S (2014) Electrochemical sensor based on overoxidized dopamine polymer and 3, 4, 9, 10-perylenetetracarboxylic acid for simultaneous determination of ascorbic acid, dopamine, uric acid, xanthine and hypoxanthine.RSC Adv4:42632-42637
  5. Wang Y, Bi C (2013) Simultaneous electrochemical determination of ascorbic acid, dopamine and uric acid using poly (tyrosine)/functionalized multi-walled carbon nanotubes composite film modified electrode.J Mol Liq177:26-31
  6. Wang Y (2011) Simultaneous determination of uric acid, xanthine and hypoxanthine at poly (pyrocatechol violet)/functionalized multi-walled carbon nanotubes composite film modified electrode.Colloids and Surfaces B: Biointerfaces88:614-621

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