Glucose oxidase immobilized amine terminated multiwall carbon nanotubes/reduced

graphene oxide/ polyaniline/gold nanoparticles modified screen-printed carbon electrode

for highly sensitive amperometric glucose detection

DebasisMaity1,C.R.Minitha 2, R. T. Rajendra Kumar 1, 2, 3*1DRDO - Center for Life Sciences, Bharathiar University, Coimbatore -641046, 2Advanced Materials and Devices Laboratory (AMDL), Department of Physics, Bharathiar

University, Coimbatore, 641 046, Tamil Nadu, India.3,*Department of Nanoscience and Technology, Bharathiar University, Coimbatore - 641046,

Tamil Nadu, India.

* Corresponding Author: rtrkumar@buc.edu.in

S1: SEM image of (a) NH2-MWCNTs (b) PANI (c) rGO (d) PANI/rGO/NH2-MWCNTs nanocomposite

S2: XRD analysis of (a)AuNP (b) PANI (d)MWCNTs (d) AuNP/PANI/rGO/NH2-MWCNTs

S3: Impedance spectroscopy profile of modified screen printing electrode using 0.1 M pH

7.0 PBS containing 1 mM [Fe(CN)6]3-/4- with 0.1 V/s scan rate.

S4: CVs of SPCE at different scan rates (10–100mV⋅s−1)

S5: Cyclic Voltammetry profile of Glucose oxidase coated AuNP/PANI/rGO/NH2-

MWCNTs modify screen printing electrode in 0.1 M pH 7.0 PBS with out glucose and with

glucose.

S1(a-d) illustrates the SEM images of different nanomaterials and their composite, which was

deposited on the screen-printed electrode for glucose biosensing application. S1(a) shows that

NH2-MWCNTs have a uniform network with the length of 1-5 µM, S1(b) shows that the

formation of polyaniline. SEM image of rGO flakes was shown in S1(c). From the SEM images

(S1(d)), it was confirmed that the formation of nanocomposite (PANI/rGO/NH2-MWCNTs).

S1: SEM image of (a) NH2-MWCNTs (b) PANI (c) rGO (d) PANI/rGO/NH2-MWCNTs

nanocomposite.

(d)(c)

(b)(a)

S2: XRD analysis of (a)AuNP (b) PANI (d)MWCNTs (d) AuNP/PANI/rGO/NH2-MWCNTs

XRD analysis

The Bragg reflections were presented in XRD analysis, which can be indexed on the basis of the face centered cubic fcc structure of gold. The diffraction peaks at 2 = 38 (111) , 44 (200), 64 (220) and 77 (311) obtained are undistinguishable with those described for the standard gold metal . Thus, the XRD pattern recommends that the gold nanoparticles were basically

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crystalline.The PANI peak diffracted at an angle of 2θ=25.602° shows low crystallinity of the conductive polymers due to the repetition of quinoid rings in PANI chains. The characteristic peak of MWCNTs for crystalline plane of (002), (101), (004) and (110) was found at 26°, 42°, 54° and 78° respectively. The diffraction intensity value of AuNP/PANI/rGO/NH2-MWCNTs nanocomposite for NH2-MWCNTs, AuNP and rGO was reduced due to present of excess amount of PANI.

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SPE/GOx rGO/GOx COOH-MWCNTs/GOx NH2-MWCNTs/GOx AuNP/GOx PANI/GOx PANI/NH2-MWCNTs/GOx rGO/NH2-MWCNTs/GOx AuNP/PANI/rGO/NH2-MWCNTs/GOx

Zim

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SPE/GOx rGO/GOx COOH-MWCNTs/GOx NH2-MWCNTs/GOx AuNP/GOx PANI/GOx PANI/NH2-MWCNTs/GOx rGO/NH2-MWCNTs/GOx AuNP/PANI/rGO/NH2-MWCNTs/GOx

Zim

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ms)

Zre (Kohms)

S3: Impedance spectroscopy profile of modified on screen printing electrode using 0.1 M

pH 7.0 PBS containing 1 mM [Fe(CN)6]3-/4- with 0.1 V/s scan rate

S4: CVs of SPCE at different

scan rates (10–

100mV⋅s−1)

S5: Cyclic Voltammetry profile of Glucose oxidase coated AuNP/PANI/rGO/NH2-

MWCNTs modify screen printing electrode in 0.1 M pH 7.0 PBS with out glucose and with

glucose

The as-prepared GOx/AuNP/PANI/rGO/NH2-MWCNTs were employed as glucose sensing

materials. The electrocatalytic activity of the GOx/AuNP/PANI/rGO/NH2-MWCNTs towards the

oxidation of glucose was investigated. Figure S6 presents the cyclic voltammograms (CVs) of

the GOx/AuNP/PANI/rGO/NH2-MWCNTs in the absence (a) and presence (b) of 1 mM glucose

0.1 M pH 7.0 PBS. In the presence of 1 mM glucose (b), a very large oxidation current was

observed at 0.4 V during the cathodic scan, representing pronounced glucose oxidation.