Synthesis of chitosan grafted poly acrylic acid (CTS-g-PAA)hydrogel and its potential application in biosensors for signalenhancing and bio analysis

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Supplementary Information

Synthesis of chitosan grafted poly acrylic acid (CTS-g-PAA) hydrogel and its potential application in biosensors for signal

enhancing and bio analysis

Esmaeel Alipour

^a,*

, Sheida Norouzi

^a

, Hajar yousefzadeh

^a

, Reza Mohammadi

^b

, Mohammad Sadegh Amini-Fazl

^c

a

Electroanalytical Chemistry Laboratory, Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran.

b

Polymer Research Laboratory, Department of Organic and Biochemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran

c

Research Laboratory of Advanced Polymer Material, Department of Applied Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran.

*Corresponding author:

Esmaeel Alipour, Email: i-alipour@tabrizu.ac.ir

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Figure S1. Schematic diagram of: (A) the CNTs preparation, and (B) NB-loaded CTS-g-PAA hydrogel synthesis

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Figure S2. (A) Histogram of sensitivity (calibration curve slope) of the sensor at different pHs. NaCl concentration:

0.025M, background electrolyte 0.1 M britton-robinson buffer solution. Other experimental conditions as cited in Fig. 2. (B) Variation of peak potential of NB versus pH.

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Figure S3. Cyclic voltammetric responses of CNT-GCE in 10 mM Fe(CN)63-/4- containing 0.2 M NaCl at scan rates of (a to k): 10, 20, 30, 40, 50, 70, 100, 125, 150, 175, 200 mV s^-1. Inset:The plot of anodic peak current vs. ʋ^1/2.

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Figure S4. Chronoamperometric responses of CNT-GCE at a potential step of -620 mV in 0.1 M phosphate buffer solutions (pH = 7) in the presence of 0.5 mM NB. Inset shows the plot of I vs. t^-1/2.

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Figure S5. FT-IR spectra of: (A) the untreated chitosan, and (B) synthesized CTS-g-PAA hydrogel.

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Figure S6. SEM image of the synthesized hydrogel A) before and B) after loading of NB.