Citrate-capped silver nanoparticles as a probe for sensitive and selective colorimetric and spectrophotometric sensing of creatinine in human urine

Journal article

Authors/Editors

Alula, Melisew

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Publication Details

Author list: Alula MT, Karamchand L, Hendricks NR, Blackburn JM

Publisher: Elsevier

Place: AMSTERDAM

Publication year: 2018

Journal: Analytica Chimica Acta (0003-2670)

Journal acronym: ANAL CHIM ACTA

Volume number: 1007

Start page: 40

End page: 49

Number of pages: 10

ISSN: 0003-2670

Languages: English-Great Britain (EN-GB)

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Abstract

Urinary creatinine concentration is a critical physiological parameter that enables reliable assessment of patient renal function and diagnosis of a broad spectrum of diseases. In this study, a simple and inexpensive sensor comprising monodisperse, citrate-capped silver nanoparticles (cc-AgNPs) was developed, which enabled rapid, sensitive and selective quantitation of creatinine directly in unprocessed urine. The mechanism of this sensor entails the creatinine-mediated aggregation of the cc-AgNPs (within 1 min) under alkaline conditions (pH 12). This is attributed to the tautomerization of creatinine to its amino anionic species at alkaline pH, which cross-link the cc-AgNPs via hydrogen bond networks with the negatively charged citrate caps. Creatinine elicited visibly-discernable color changes of the cc-AgNPs colloids in a concentration-dependent manner up to 10 mM. UV-visible spectroscopic analyses of the cc-AgNPs revealed that creatinine elicited a concentration-dependent decrease in intensity of the localized surface plasmon resonance (LSPR) band centered around 403 nm, with a concomitant increase in intensity of the red-shifted LSPR band at 670 nm. This observation denotes a creatinine-mediated increase in cc-AgNP particle size via aggregation, as confirmed by transmission electron microscopy analysis. The cc-AgNP sensor exhibited a linear correlation between the A(6/0)/A(4/3) extinction ratio and creatinine concentration range of 0-4.2 mu M in aqueous solutions ( R2 = 0.996), and a low detection limit of 53.4 nM. Hence, the simplicity, short assay time, and high sensitivity and selectivity of our cc-AgNP sensor affirms its utility as a creatinine monitoring assay for low-resource, point-of-care settings. (C) 2018 Elsevier B.V. All rights reserved.

Keywords

Aggregation, Citrate-capped silver nanoparticles, Creatinine, Localized surface plasmon resonance (LSPR), UV-Visible spectrophotometry

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