Reusable potentiometric screen-printed sensor and label-free aptasensor with pseudo-reference electrode for determination of tryptophan in the presence of tyrosine

Mir Reza Majidi; Yadollah Omidi; Pari Karami; Mohammad Johari-Ahar

doi:10.1016/j.talanta.2015.12.064

Reusable potentiometric screen-printed sensor and label-free aptasensor with pseudo-reference electrode for determination of tryptophan in the presence of tyrosine

Talanta. 2016 Apr 1:150:425-33. doi: 10.1016/j.talanta.2015.12.064. Epub 2015 Dec 25.

Authors

Mir Reza Majidi¹, Yadollah Omidi², Pari Karami³, Mohammad Johari-Ahar⁴

Affiliations

¹ Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran. Electronic address: [email protected].
² Research Center for Pharmaceutical Nanotechnology (RCPN), Tabriz University of Medical Sciences, Tabriz, Iran. Electronic address: [email protected].
³ Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran.
⁴ Research Center for Pharmaceutical Nanotechnology (RCPN), Tabriz University of Medical Sciences, Tabriz, Iran.

PMID: 26838426
DOI: 10.1016/j.talanta.2015.12.064

Abstract

Analysis of L-tryptophan (Trp) in biological samples has great importance for biomedical studies. Amino acid tyrosine (Tyr) that usually coexist with Trp in biological fluids can significantly interfere with reliable determination of Trp. In the current study, we demonstrate the development of two ultra-sensitive electrochemical sensor and label-free aptasensor for selective analysis of Trp in biological samples (i.e., cow's milk and human plasma, saliva and urine samples). In addition, without using AgCl/KCl, an Ag pseudo-reference screen printed electrode (Ag-PR-SPE) was exploited as a reference electrode. To prepare the engineered Trp sensor/aptasensor, a gold SPE was first modified with multiwall carbon nanotube (MWCNT-AuSPE) and then armed with Trp aptamer molecules (Apt-MWCNT-AuSPE). The prepared sensors were characterized using constant current-potentiometric stripping analysis (CC-PSA) and electrochemical impedance spectroscopy (EIS). The MWCNT-AuSPE and Apt-MWCNT-AuSPE were compared with respect to the linear detection range, limit of detection (LOD), accuracy, precision, repeatability. MWCNT-AuSPE and Apt-MWCNT-AuSPE demonstrate fast near-Nernstian response for PSA of Trp over the concentration ranging from 1.0 × 10(-9) to 2.0 × 10(-4) mol L(-1) and 1.0 × 10(-11) to 1.0 × 10(-4) mol L(-1) with detection limits of 3.6 × 10(-10) mol L(-1) and 4.9 × 10(-12) mol L(-1), respectively. Common interfering species present in the biological fluids (i.e., tyrosine, uric acid, ascorbic acid) showed no effects on the determination of Trp using CC-PSA. MWCNT-AuSPE and Apt-MWCNT-AuSPE represented well reproducibility and great precision with relative standard deviation (RSD) of 2.9% and 5.3% respectively. In comparison with the MWCNT-AuSPE, Apt-MWCNT-AuSPE provided higher sensitivity, selectivity and accuracy of Trp detection in real samples. Based on these findings, we propose the developed Apt-MWCNT-AuSPE as a simple detection method for analysis of Trp in biological samples.

Keywords: Multiwall carbon nanotube; Potentiometric stripping analysis; RNA aptamer; Screen-printed electrode.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Aptamers, Nucleotide*
Base Sequence
Biosensing Techniques / instrumentation*
Electric Conductivity
Electrochemistry
Electrodes
Equipment Reuse
Humans
Limit of Detection
Milk / chemistry
Nanotubes, Carbon / chemistry
Potentiometry / instrumentation*
Printing*
Saliva / chemistry
Silver / chemistry
Tryptophan / analysis*
Tryptophan / blood
Tryptophan / urine
Tyrosine / analysis*

Substances

Aptamers, Nucleotide
Nanotubes, Carbon
Silver
Tyrosine
Tryptophan