Ultrasensitive electrochemical sensing of phosphate in water mediated by a dipicolylamine-zinc(II) complex

https://doi.org/10.1016/j.snb.2020.128474Get rights and content
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Highlights

  • Zinc(II)-dipicolylamine-modified gold electrodes were used for first time for electrochemical sensing of phosphate in water.

  • Electrochemical detection is due to perturbation of pyridine redox properties upon interaction of metal centre with phosphate.

  • LOD of phosphate sensing amounts to 7.5 × 10−16 M.

  • Negligible electrochemical response of the electrode towards sulfate demonstrates high selectivity of detection.

Abstract

Dipicolylamine-zinc(II) complexes immobilized on gold electrodes allowed the selective electrochemical phosphate detection. The electrodes were prepared by assembling monolayers containing either (R)-N-(6-(bis(pyridine-2-ylmethyl)amino)hexyl)-5-(1,2-dithiolan-3-yl)pentanamide (DPA-hexyl) or (R)-N-(12-(bis(pyridine-2-ylmethyl)amino)dodecyl)-5-(1,2-dithiolan-3-yl)pentanamide (DPA-dodecyl) together with 4-mercapto-1-butanol (MB) on gold surfaces and subsequently adding zinc(II)nitrate to produce the corresponding surface-bound zinc(II) complexes. Both sensing systems displayed high sensitivity towards phosphate with detection limits close to 1.0 × 10–15 M. Sensing was moreover very selective since sulfate, having a similar tetrahedral structure like phosphate, generated only a negligible electrochemical response. These electrodes were shown to allow the quantification of phosphate ions in lake water sample. Electrochemical studies indicated that the sensing mechanism was based on the redox activity of the pyridine units in the ligands complexed with Zn(II).

Keywords

Gold electrodes
Self-assembling monolayer
Dipicolylamine-zinc(II) complexes
Electrochemical phosphate sensing
Water

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Unni Sivasankaran received his PhD in chemistry from Department of Applied Chemistry, Cochin University of Sciences and Technology (India). He spent one year on postdoc fellowship in Biosensors Department, Institute of Animal Reproduction and Food Research of Polish Academy of Sciences. His research interests cover anion recognition, sensor development, electro-catalysis and nanomaterials.

Lena Reinke studied chemistry at Technische Universität Kaiserslautern (TUK). Her master thesis concerned the development of sulfur-containing supramolecular receptors for immobilization on the gold. Currently, she is a PhD student in professor Stefan Kubik group, working on gold nanoparticles-based optical probes for anion recognition in aqueous media.

Sanu K. Anand is a PhD course student at the Department of Applied Chemistry, Cochin University of Sciences and Technology (India). Her research is focused on the development of electrochemical and optical sensors for clinical analysis.

Kamila Malecka since 2009 is working at Department of Biosensors in the Institute of Animal Reproduction and Food Research of Polish Academy of Sciences in Olsztyn. She obtained PhD degree in chemistry under supervision of professor Jerzy Radecki. Her research focused on the development of genosensors based on ion-channel mimetic mode and redox active monolayers. These biosensors are destined for determination of AIV H5N1 and Plum Pox viruses.

K. Girish Kumar received Bachelor and Post Graduate degree in Chemistry from University of Kerala in 1982 and 1984 respectively. In 2006 he became professor of analytical chemistry and has served as head of the Department of Applied Chemistry, Cochin University of Sciences and Technology (India). Presently he is a Dean of Faculty of Science and also chairman of chemistry board in CUSAT. His research concerns the development of optical/fluorescent and electrochemical sensors for determination of metal ions, pharmaceuticals, biologically active molecules and food additives.

Hanna Radecka was graduated from the Department of Chemistry of Nicolaus Copernicus University in Toruń in 1978. She was a visiting scientist at the Hokkaido University in Sapporo and at the University of Tokyo. Since 1998, she is working at Department of Biosensors of the Polish Academy of Sciences in Olsztyn. In 2011 she received the title of professor of analytical chemistry and was nominated as the head of Laboratory of Bioelectroanalysis. Currently, she is working on the development of the new biosensors for determination of avian influenza viruses, possible biomarkers of Alzheimer’s and other neurodegenerative diseases present in human plasma.

Stefan Kubik studied chemistry at Heinrich-Heine-Universität in Düsseldorf and at King's College in London. He graduated in 1987 with a diploma thesis in the group of Prof. Dr. G. Wulff, and received his pH.D. in 1992 for work that he carried out in the same group about structural aspects of complexes of amylose with organic guest molecules. He worked for a while independently on a related topic before a NATO-fellowship allowed him in 1993 to spend one year as a post-doc in the group of Prof. J. Rebek Jr. at M.I.T. During this time, he studied self-replicating and self-assembling systems. Since November 2004, he is full professor at University of Kaiserslautern. The main research fields of his group lie within supramolecular chemistry, in particular, molecular recognition in water.

Jerzy Radecki is the professor of analytical chemistry and currently working as head of Department of Biosensors of IARFR PAS in Olsztyn. His research interest concerns the developing of new sensors and biosensors based on the intermolecular recognition processes occurring at the border of the aqueous and organic phase. Particularly, he is interested in functionalization of surface of solid electrodes with “host” molecules, which are responsible for “guest” molecules (analytes) recognitions. He is working on not only analytical aspects of developed sensors, but also on the elaboration of the mechanism of analytical signal generation.