Electronic Supporting Material on the Microchimica Acta publication

Molybdenum Disulfide Quantum Dot Based Highly Sensitive Impedimetric

Immunoassay for Prostate Specific Antigen

Manil Kukkar1,2#, Suman Singh1,2#, Nishant Kumar1, Satish K. Tuteja3, Ki-Hyun Kim4*, Akash

Deep1,2*

1CSIR-Central Scientific Instrument Organisation (CSIR-CSIO), Chandigarh 160030, India2Academy of Scientific and Innovative Research (AcSIR-CSIO), Chandigarh 160030, India3BioNano Laboratory, School of Engineering, University of Guelph, Guelph, ON N1G

2W1, Canada4Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-

Ro, Seoul 04763, Korea#Equal contribution for first authorship

Correspondence: kkim61@hanyang.ac.kr, Tel.: +1-82-2-2220-2325; Fax: +82-2-2220-19451

dr.akashdeep@csio.res.in, Tel: +91-172-2672236, Fax: +91-172-2657287

Figure S1: Schematic for the synthesis and bioconjugation of MoS2 QDs along with the development of immunoassay for PSA

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Figure S2: 2 and 3-Dimensional AFM images of MoS2-QDs along with the line profile

analysis [Features of the AFM Tip used for the scanning of samples: (a) Make- ATEC-NC-

10, (b) Radius of curvature (R) of tip ≥ 10 nm, and (c) Achievable resolution of the tip ~ 2.82

nm (calculated by standard equation of Resolution = (0.8 R)^1/2)].

Measurement parameter Bare SPCE SPCE/MoS2 QDs

Contact angle (°) 73 80.05Surface free energy (mN/m) 31.77 ±0.00 28.98 ±0.17

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Figure S3: Contact angle measurement of bare and MoS2 QD modified SPCE. An increased

contact angle suggests the improved hydrophobicity of the MoS2 QD modified SPCE.

Figure S4: (a) Raman spectrum of MoS2-QDs and bulk MoS2, (b) XRD spectra of bulk MoS2

& MoS2-QDs, (c) EDX analysis of MoS2-QDs, and (d) FE-SEM analysis of MoS2-QDs

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Figure S5: (a) UV-visible spectra of MoS2 QDs and nanosheets and (b) Fluorescence

spectrum of MoS2 QDs

Figure S6: Current voltage response of Bare SPCE (left) and SPCE/MoS2QD modified (right).

Figure S7: Investigations on the reproducibility of the response of different SPCE/MoS2

QD/PSAAb electrodes. The EIS responses of five electrodes made in different batches were

found to be overlapping with each other, thereby proving their reproducibility.

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Figure S8: (a) Selectivity study with the SPCE/MoS2QD/PSAAb electrodes [concentrations of

PSA and other tested proteins were 0.01 and 1 pg⋅mL-1, respectively] and (b) Response of

the SPCE/MoS2QD/PSAAb electrodes with spiked PSA both in standard buffer and serum

samples

Table S1. An overview on recently reported nanomaterial-based methods for determination of PSA

S. No.

Materials used Method Applied Linearity range

Limit of detection

Specificity Ref.

01 Nano-TiO2-modifiedcarbon paste electrode

Impedance spectroscopy 0.10-5.0 and 5.0-100 ng⋅mL-1

200 pg⋅mL-1 Specific with respect to carcinoembryonic antigenthyroid-stimulating hormone

[1]

02 Gold film Micro fluxgate device involving sandwichimmunoassay

0.1-10.0 ng⋅mL−1

0.1 ng⋅mL−1 Specific with respect to bovine serum albumin, carcinoembryonicantigen and alpha fetoprotein

[2]

03 Multi-walled carbon nanotubes

Sandwich type immunosensor with differentialpulse voltammetry

0.01-100 ng⋅mL−1

5.4 pg⋅mL-1 Specific with respect to carcinoembryonic antigen, myoglobin, mucoprotein and thrombin

[3]

04 Goldnanoparticles

Differentialpulse voltammetry

0.25-200 ng⋅mL−1

0.25 ng⋅mL−1

Specific with respect to bovine

[4]

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covered with graphitized mesoporouscarbon nanoparticles

serum albumin, hemoglobin and thrombin

05 Functionalized graphene QDs

Electro-chemiluminescence

1-10 pg⋅mL−1

0.29 pg⋅mL−1

Specific with respect to carcinoembryonic antigen, bovine serum albumin glucose

[5]

06 Graphene oxide hybridized with ferrocene monocarboxylic acid

Differential pulse voltammetry

2 pg⋅mL−1 - 10 ng⋅mL−1

0.5 pg⋅mL−1 Specific with respect to Human immunoglobin M, human immunoglobin G, carcinoembryonic antigen, glucoseand thrombin

[6]

07 Graphene sheets–methylene blue–chitosan

Amperometry 0.05–5 ng⋅mL−1

13 pg⋅mL−1 Specific with respect to alpha fetoprotein, bovine serum albumin, vitamin C and glucose

[7]

08 Composite of Fe3O4 nanoparticlesand reduced graphene oxide

Sandwich type electrochemical immunoassay

0.1 pg⋅mL−1

- 5 ng⋅mL−10.03 pg⋅mL-

1Specific with respect to bovine serum albumin, carbohydrate antigen-125, carcinoembryonicantigen and alpha fetoprotein

[8]

09 Reduced graphene oxide functionalized with High molecular-weight silk peptide

Differential pulse voltammetry

0.1 - 80 ng⋅mL−1

53 pg⋅mL-1 Specific with respect to alpha-fetoprotein, human immunoglobin, bovine serum albumin, L-cysteine and L-Lysine

[9]

10 MoS2 QDs Impedance spectroscopy 0.01 pg⋅mL−1

- 200 ng⋅mL−1

0.01 pg⋅mL−1

Specific with respect to human serum albumin, carcinoembryonic antigen, Immunoglobin G and alpha-fetoprotein

This work

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Table S2. PSA detection in spiked serum samples and recovery study

S. No. PSA Concentration[spiked (ng⋅mL-1)]

Rct (ohms) obtained with standard

samples

Rct (ohms) obtained with spiked serum

samples

Recovery (%)

01 1.0 × 10-5 5519 ± 25 5413 ± 27 102 ± 2.2

02 1.0 × 10-3 7189 ± 29 7143 ± 30 100 ± 2.6

03 1.0 × 10-1 8518 ± 35 8618 ± 39 98 ± 3.5

04 1.0 × 102 12187 ± 52 12339 ± 55 98 ± 2.5

Note that all the data reported herein are an average of triplicate analysis

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