Application of Gold Nanoparticles to Spectrophotometric Sensing of Hydrophilic Anions Based on Molecular Recognition by Urea Derivative

Abstract

We have prepared gold nanoparticles (GNPs) modified with a thiol compound that possesses a phenylurea moiety for the spectrophotometric sensing of hydrophilic anions, such as dihydrogen phosphate, based on changes in the surface plasmon absorption of the GNP. We examined the spectral change of phenylurea-modified GNP in dichloromethane upon the addition of various anions as tetrabutylammonium salts to the solution. The GNP showed increasing plasmon intensity with the concentration of dihydrogen phosphate. For a control experiment with an inactive hexanethiolate-modified GNP, such an ion-selective change in the plasmon band was not observed. Furthermore, in order to realize the spectrophotometric detection of hydrophilic anions in water using GNP with the urea functionality, we attempted to prepare bifunctional GNP modified with both the phenylurea derivative and a water-soluble thiol (e.g., L-cysteine). The resulting bifunctional GNP showed anion-selective changes in the plasmon band accompanied by increasing absorbance at a longer wavelength due to GNPs aggregation.

Complexation of phosphates by 1,3-bis(3-(2-pyridylureido)propyl)-1,1,3,3-tetramethyldisiloxane

“…Compounds containing a urea or thiourea moiety form complexes with anions thanks to the ability to form quite strong hydrogen bonds . Some urea (or thiourea) conjugates were prepared in order to form stable complexes with the phosphate anion (usually with dihydrogen phosphate H 2 PO 4 − ) . From the biological point of view, complexation of organic phosphates is more important than complexation of phosphate anions, Therefore, the literature gives many examples of synthesized organic compounds capable of formation of complexes with nucleotides .…”

Gold and Silver Nanomaterial‐Based Optical Sensing Systems

“…Au NPs conjugated with phenyl urea were used for the detection of an common anion such as H 2 PO 4 2− . Through a specific interaction with the isothiouronium of the conjugated Au NPs, the analyte‐induced aggregation of Au NPs.…”

A colorimetric probe based on desensitized ionene-stabilized gold nanoparticles for single-step test for sulfate ions

“…Lots of colorimetric techniques based on AuNPs for the determination of different organic compounds [10][11][12][13][14][15][16][17][18], metal ions [19][20][21][22][23][24][25][26][27][28], and other analytes have been suggested for the past ten years. The AuNPs-based colorimetric platform has also found an application for sensing anions, including dihydrophosphate [29,30], hydrophosphate [31], fluoride [32,33], cyanide [34], nitrite [35], sulfide [36], and hypochlorite [37]. AuNPs have been only once reported as a colorimetric probe for the detection of sulfate [38].…”