Supporting information

An electrochemical immunosensor based on a 3D carbon system consisting of

a suspended mesh and substrate-bound interdigitated array nanoelectrodes

for sensitive cardiac biomarker detection

Deepti Sharma, Jongmin Lee, Heungjoo Shin*

Department of Mechanical Engineering, Ulsan National Institute of Science and Technology

(UNIST), Ulsan 44919, Republic of Korea

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Fig. S1. Schematic fabrication steps of 3D carbon system consisting of a suspended mesh and

IDA nanoelectrodes.

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Fig. S2. Steps for covalent immobilization of monoclonal anti-cardiac myoglobin (mAb-cMyo)

antibody on the suspended carbon mesh surface (EDC: 1-Ethyl-3-(3-dimethylaminopropyl)-

carbodiimide, NHS: N-Hydroxysuccinimide).

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Fig. S3. SEM images of a 3D carbon system: (A) top view. (B) Enlarged top view. (C) Side

view.

Fig. S4. Cyclic voltammograms of a suspended carbon mesh in ice cold solution containing 20

mM of 4-carboxymethylaniline (CMA), 15 mM NaNO2, and 15 mM HCl at potential from 0.5 to

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–1.0 V vs. Ag/AgCl, and a scan rate of 200 mV/s.

Fig. S5. (A) Schematic diagram of the model geometry used in the simulation (cut as per one

half of a single mesh). (B) Simulation results of the concentration profile of PAP for a 3D carbon

system. The black arrows describe the fluxes of PAP.

Fig. S6. Anodic current ratios for various distances between the mesh and the IDA electrodes (Io

= anodic current collected from the 3D carbon system with a 3.3 m mesh-to-IDA distance). The

red dot indicates the anodic current ratio corresponding to the geometry of the presented 3D

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carbon system.

Fig. S7. Chronoamperograms from generator comb of substrate-bound IDA nanoelectrodes in

various concentration (0 to 100 ng/mL) of cardiac myoglobin (cMyo) containing 1 mM PAPG in

0.1 M PBS (pH = 7.5) (applied potential = +0.29 V vs. Ag/AgCl).

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Fig. S8. (A) Amperometric current response obtained from a generator comb of substrate-bound

IDA nanoelectrodes prepared with selective covalent binding (black square) and non-selective

physical binding (blue circle) of mAb-cMyo on the suspended mesh electrode for various

concentrations (0–100 ng/mL) of cardiac myoglobin (cMyo) in 1 mM PAPG in 0.1 M PBS (pH =

7.5). (B) Corresponding calibration curves of amperometric current response with respect to the

logarithm of cMyo concentration for both the binding conditions.

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Fig. S9. Amperometric current responses at carbon IDA nanoelectrodes for five different 3D

carbon system-based immunosensors with 0.1 ng/mL of cardiac myoglobin (cMyo) in 1 mM

PAPG in 0.1 M PBS (pH = 7.5).

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Table S1. Comparison of the basic performance characteristics of various sensing platforms for

cardiac myoglobin (cMyo).

Platform Detection range LOD(µM) Detection Method Reference

Molecularly imprinted polymer assembled on a polymeric layer of carboxylatedpoly (vinyl chloride)

0.852-4.26 µg/mL 2.25 µg/mL Square wave voltammetric (SWV) Moreira et al., 2013

Graphene oxide/multiwalled car-bon nanotubes nanostructured electrode 1 -4 ng/mL 0.34 ng/mL Cyclic voltammetry (CV) Kumar et al., 2015

Au nanoparticles/arginine-glycine-aspartic/carboxylated graphene/glassy carbon electrode 0.1-200 µg/mL 26.3 ng/mL Differential pulse

voltammetry (DPV) Li et al., 2017

Y-shape structure of dual-aptamer -complementary strand of aptamer conjugate,gold electrode and exonucleaseI

1.75-700 ng/mL 0.45 ng/mL Differential pulse voltammetry (DPV) Taghdisi et al., 2016

Label-free supersandwichelectrochemical biosensor 0.17-1750 ng/mL 0.16 ng/mL Chronocoulometry Wang et al., 2014

Thin flat gold wire electrode modified with self assembled monolayer of 11-mercaptoundecanoic acid and 3-mercapto propionic acid

10-650 ng/mL 5.2 ng/mL Electrochemical impedance spectroscopy (EIS) Rajesh et al., 2010

Graphene quantum dots modified screen printed electrode 0.01-100 ng/mL 0.01 ng/mL

Differential pulse voltammetry (DPV) Tuteja et al., 2016

Screen-printed multiwalled carbon nanotubes 0.1-90 ng/mL 0.08 ng/mL Electrochemical impedance

spectroscopy (EIS) Khan et al., 2016

Nanogold-penetrated poly(amidoamine) dendrimer 0.01-500 ng/mL 3.8 pg/mL Stripping voltammetry

method Zhang et al., 2016

3D carbon system (Antibody modified suspended carbon mesh) 0.001-100 ng/mL 0.43 pg/mL Chronoamperometry This work

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