Naked-Eye Detection of 3-Nitro-1,2,4-triazole-5-one at Sub-Femtomolar Levels with Melamine and Unlabeled Au Nanoparticles

Abstract

In this paper, a simple and rapid nanosensing assay was developed for 3-nitro-1,2,4-triazole-5-one (NTO) exploiting target-directed adsorption by unlabeled gold nanoparticles (AuNPs) and competitive supramolecular association of NTO with melamine (MEL). While AuNPs aggregated in the presence of MEL with a color change from red to blue, AuNPs remained dispersed and retained their original plasmonic red color with the addition of NTO, owing to the hydrogen bonding affinity of the NTO triazole ring to MEL. The concentration of NTO leading to color change could be determined with the naked-eye even at the sub-femtomolar level. Analytical results showed that the absorption ratio (A 520nm/A 630nm) varied linearly with the logarithm of NTO concentration in the range of 3.08 × 10–16 to 3.08 × 10–12 mol L–1 with a correlation coefficient of 0.9994. The synthesized and resultant AuNPs (in the presence of NTO and/or MEL) were characterized using ultraviolet–visible spectrophotometry, scanning transmission electron microscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, and ζ-potential measurements. Possible interferences of various energetic substances in synthetic mixtures containing 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenol, hexahydro-1,3,5-trinitro-1,3,5-triazine, and ammonium nitrate, of possible camouflage materials used in passenger belongings such as cationic surfactants (cetyltrimethylammonium bromide and cetylpyridinium chloride), d-(+)-glucose as a representative sugar, acetylsalicylic acid- and paracetamol-based painkiller drugs, and of commonly found soil ions (Cl–, NO3 –, SO4 2–, Ca2+, Mg2+, CuII, FeII/III, and AgI) were also examined. In addition, recovery of NTO was successfully performed from NTO-based melt-cast formulations consisting of mixtures of TNT and NTO. The proposed method was statistically validated against a reference liquid chromatography–tandem mass spectrometry method applied to NTO standards, NTO-contaminated soil, and loam samples.

Real-Time Probing of Melamine-Induced Gold Nanoparticle Aggregation Kinetics via Evanescent-Wave Coupled Cavity Ring-down Spectroscopy

“…37,38 We speculate the probable structure formation (as proposed in Figure 2a) in the presence of melamine from some proven facts: the surface chemistry of citrate-capped GNPs, 26,39,40 the hydrogen bond acceptor group on the surface of GNPs 40,41 and the hydrogen donor group of melamine. 8,9,38 FTIR spectra show distinct halos for melamine and the carboxylate group of citrates at 3100−3650 cm −1 and 1600−1650 cm −1 , respectively (Figures S8 and S9). The peak in the range of 1600−1650 cm −1 red-shifted for a higher concentration of melamine, indicating a higher concentration of hydrogen bond formation due to the melamine molecule with the carboxylate group of citrates adhering to the GNP.…”

“…35,36 However, little to no information was reported about the interaction of melamine with citrate-capped GNPs at the molecular level rather than a formal colorimetric study. 37,38 We speculate the probable structure formation (as proposed in Figure 2a) in the presence of melamine from some proven facts: the surface chemistry of citrate-capped GNPs, 26,39,40 the hydrogen bond acceptor group on the surface of GNPs 40,41 and the hydrogen donor group of melamine. 8,9,38 FTIR spectra show distinct halos for melamine and the carboxylate group of citrates at 3100−3650 cm −1 and 1600−1650 cm −1 , respectively (Figures S8 and S9).…”

“…To some extent, we have estimated the interaction between the GNP and melamine by ATR-FTIR, as we can use the aggregated sample in liquid form. FTIR has been widely used to characterize the basic skeleton structure of melamine and is significant in determining the hydrogen bonding environments. , However, little to no information was reported about the interaction of melamine with citrate-capped GNPs at the molecular level rather than a formal colorimetric study. , We speculate the probable structure formation (as proposed in Figure a) in the presence of melamine from some proven facts: the surface chemistry of citrate-capped GNPs, ,, the hydrogen bond acceptor group on the surface of GNPs , and the hydrogen donor group of melamine. ,, FTIR spectra show distinct halos for melamine and the carboxylate group of citrates at 3100–3650 cm –1 and 1600–1650 cm –1 , respectively (Figures S8 and S9). The peak in the range of 1600–1650 cm –1 red-shifted for a higher concentration of melamine, indicating a higher concentration of hydrogen bond formation due to the melamine molecule with the carboxylate group of citrates adhering to the GNP.…”

Determination of ketamine using melamine-modified gold nanoparticles

“…Three hydrogen acceptor (NH) and six hydrogen donor (NH 2 ) groups are present in each melamine molecule arising from the presence of exocyclic amino substituents and a triazine ring, respectively. As a result, melamine molecules can create nine hydrogen bonds at the maximum [ 41 ]. Ketamine, on the other hand, belongs to the category of cyclohexanones where one of the hydrogen atoms at position 2 is replaced by a 2-chlorophenyl group and the other by a methylamino group.…”

Spectrophotometric and Smartphone-based Dual Monitoring Method for the Determination of Al(III) Ions Using Fermented Black Carrot Juice (Şalgam/Shalgam) as a Green Chromogenic Agent

“…Furthermore, the limit of detection (LOD) and the limit of quantification (LOQ) values are 6.67 µM and 22.0 µM, respectively. The limit of detection was calculated in micromole per liter units according to the literature (43,44). (LOD = 3σblank/antilog m, LOQ = 10σblank/antilog m where σblank denotes the standard deviation of a blank and m shows the slope of the calibration line).…”