Indium Tin Oxide with Zwitterionic Interfacial Design for Biosensing Applications In Complex Matrices

Applied Surface Science 325 (2015) 91–99

9 Pages Posted: 12 Jul 2017

See all articles by Nadia Darwish

Nadia Darwish

University of Malaya (UM) - Department of Chemistry

Yatimah Alias

University of Malaya (UM) - Department of Chemistry

Sook Mei Khor

University of Malaya (UM) - Department of Chemistry

Date Written: January 7, 2016

Abstract

Biosensing interfaces consisting of linker molecules (COOH or NH) and charged, antifouling moieties ((SO3− and N (Me)32) for biosensing applications were prepared for the first time by the in situ deposition of mixtures of aryl diazonium cations on indium tin oxide (ITO) electrodes. A linker molecule is required for the attachment of biorecognition molecules (e.g., antibodies, enzymes, DNA chains, and aptamers) close to the transducer surface. The attached molecules improve the biosensing sensitivity and also provide a short response time for analyte detection. Thus, the incorporation of a linker and antifouling molecules is an important interfacial design for both affinity and enzymatic biosensors. The reductive adsorption behavior and electrochemical measurement were studied for (1) an individual compound and (2) a mixture of antifouling zwitterionic molecules together with linker molecules [combination 1: 4sulfophenyl (SP), 4-trimethylammoniophenyl (TMAP), and 1,4-phenylenediamine (PPD); combination 2: 4-sulfophenyl (SP), 4-trimethylammoniophenyl (TMAP), and 4-aminobenzoic acid (PABA)] of aryl diazonium cations grafted onto an ITO electrode. The mixture ratios of SP:TMAP:PPD and SP:TMAP:PABA that provided the greatest resistance to non-specific protein adsorptions of bovine serum albumin labeled with fluorescein isothiocyanate (BSA–FITC) and cytochrome c labeled with rhodamine B isothiocyanate (RBITC–Cyt c) were determined by confocal laser scanning microscopy (CLSM). For the surface antifouling study, we used 2-[2-(2-methoxyethoxy) ethoxy]acetic acid (OEG) as a standard control because of its prominent antifouling properties. Surface compositions of combinations 1 and 2 were characterized using X-ray photoelectron spectroscopy (XPS). Field-emission scanning electron microscopy (FE-SEM) was used to characterize the morphology of the grafted films to confirm the even distribution between linker and antifouling molecules grafted onto the ITO surfaces. Combination 1 (SP:TMAP:PPD) with a ratio of 0.5:1.5:0.37 exhibited the best antifouling capability with respect to resisting the nonspecific adsorption of proteins.

Keywords: Biosensor, Indium tin oxide, Anti-biofouling coating, Zwitterionic molecules

JEL Classification: I1, I10

Suggested Citation

Darwish, Nadia and Alias, Yatimah and Khor, Sook Mei, Indium Tin Oxide with Zwitterionic Interfacial Design for Biosensing Applications In Complex Matrices (January 7, 2016). Applied Surface Science 325 (2015) 91–99. Available at SSRN: https://ssrn.com/abstract=2712114

Nadia Darwish

University of Malaya (UM) - Department of Chemistry

Jalan Lembah Pantai
Kuala Lumpur, Wilayah Persekutuan 50603
Malaysia

Yatimah Alias

University of Malaya (UM) - Department of Chemistry ( email )

Jalan Lembah Pantai
Kuala Lumpur, Wilayah Persekutuan 50603
Malaysia

Sook Mei Khor (Contact Author)

University of Malaya (UM) - Department of Chemistry ( email )

Kuala Lumpur, Wilayah Persekutuan 50603
Kuala Lumpur, Wilayah Persekutuan 50603
Malaysia

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