Simple optical determination of silver ion in aqueous solutions using benzo crown-ether modified gold nanoparticles (original) (raw)
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Sensors and Actuators B: Chemical, 2010
Gold nanoparticles functionalized with mixtures of 1-hexanethiol and 4-mercaptophenol were investigated as chemiresistor sensors for use in aqueous solutions. X-ray photoelectron spectroscopy (XPS) studies confirmed that it was possible to form mixed ligand compositions on the surface of the nanoparticles. Nanoparticle films with a higher proportion of 1-hexanethiol as the ligand resulted in higher impedances than those with lower proportions. The electrical response of the chemiresistor to toluene, dichloromethane, hexane and ethanol dissolved in water was found to depend strongly on the composition of the organic ligand used to cap the gold nanoparticles. 1-Hexanethiol-coated gold nanoparticles were sensitive to non-polar analytes whereas the sensitivity was reduced upon increasing the composition of 4-mercaptophenol on the surface. It was also shown that the sensitivity to ethanol could be enhanced 3-fold by using a sensor that was functionalized with a mixture of 60% 1-hexanethiol and 40% 4-mercaptophenol compared to a sensor functionalized with pure thiols only.
Application of nanoparticle modified with crown ether in colorimetric determinations
Arabian Journal of Chemistry, 2015
There is a general need to develop simple, rapid, and inexpensive detection assays for diagnostic applications and environmental analysis. Currently, most analyses are performed under laboratory conditions, frequently with the assistance of expensive instruments and trained personnel. Colorimetric sensors as dipsticks or in a chromatographic format would be ideal for the various analyses. These sensors need minimal instrumentation and achieve high sensitivity. In recent years, metallic nanoparticles especially gold nanoparticles and silver nanoparticles have been widely used as colorimetric probes for chemical sensing and biosensing. This interesting application is due to their unique size-dependent, interparticle distance dependent, absorption spectra and solution color. When the nanoparticles approach each other and aggregate, the color of the nanoparticles changes from red to purple (or blue) for gold nanoparticles and from yellow to red (or dark green) for silver nanoparticles respectively. This phenomenon is due to the shift of the surface plasmon band to longer wavelength. Crown ethers are known for the unusual property of forming stable complexes with cations. The oxygen atoms lie in a nearly planar arrangement about the central cation. Today the development of crown ether functional nanoparticle as colorimetric sensors is a subject of considerable interest. In this article we investigated on the use of nanoparticle modified with crown ether for sensing of metal ions and also charged molecules with colorimetric technique.
Analytical and Bioanalytical Chemistry, 2019
To develop bioconjugated materials, it is necessary to understand how the various elements present in a conjugate interact with one another. To gain insights into nanoparticle-capping agent-protein interactions, gold nanoparticles (AuNPs) measuring 30 nm in diameter were coated with different molecules bearing a thiol group: 3mercaptopropionic acid, 6-mercaptohexanoic acid, and 11-mercaptoundecanoic acid. The covalent conjugation of AuNPs to the protein bovine serum albumin (BSA) via a cross-linker reaction with N-hydroxysuccinimide and 1ethyl-3-(3-dimethylaminopropyl)carbodiimide was systematically investigated under different reaction conditions with variation of the concentrations of the mercaptoalkyl carboxylic acid (MA) and BSA. All the products were analyzed by UV-vis spectroscopy, gel electrophoresis, and Raman spectroscopy in every modification step. From analysis of the UV-vis results, it is possible at low concentrations of MA to see strong coupling among AuNPs, observed when they are aggregated by KCl, which does not happen at higher concentration of MA, indicating an AuNP-to-MA ratio of 1:130,000 is best for bioconjugation purposes. Agarose gel electrophoresis, a classic technique for biomolecule characterization, indicated that BSA is capable of altering the mobility of AuNPs when it modifies completely the surface of AuNPs because of its high molecular mass (around 66 kDa). Principal component analysis of surface-enhanced Raman spectroscopy data was successfully used as a chemometric tool to assist the characterization of the nanoparticle modification with linker molecules in the absence and presence of different BSA concentrations, making it possible to clearly evaluate the gradual substitution/modification of AuNPs (1:13,000 < 1:65,000 < 1:130,000 AuNP-to-MA ratio) and the conjugation with BSA, which is homogenous at a concentration of 0.01 g L-1 .
Microchimica Acta, 2011
Preparation of 2-[3-(2-amino ethylsulfanyl)-propylsulfanyl]-ethylamine (AEPE) Sodium metal (1 g, 43 mmol) was added to cysteamine hydrochloride (2.3 g, 20 mmol) and stirred at 15 C for 15 min under a nitrogen atmosphere. 1,3-Dibromopropane (1 mL, 9.8 mmol) was added slowly and then stirred at 40 C for an additional 4 h. After solvent removal by evaporation, sodium hydroxide (30% (w/v), 15 mL) was added to the residue and stored in a refrigerator overnight. The solution was extracted once with 20 mL of dichloromethane and washed twice with 20 mL of ultra-pure water and then dried over anhydrous Na 2 SO 4. After solvent removing and drying in vacuum, the yellow oil product (AEPE), with a quantitative yield of 80%, was used without further purification. 1 H-NMR (400 MHz, CDCl 3) (ppm) 2.77 (t, 4H, CH 2 NH 2 , J = 6.4 Hz), 2.52 (t, 8H, SCH 2 , J = 6.3 Hz) and 1.76 (t, 2H, CH 2 CH 2 CH 2 , J =7 .02 Hz). 13 C-NMR (400 MHz, CDCl 3) (ppm) 29.40 (1C, CH 2 CH 2 CH 2), 30.46 (2C, SCH 2 CH 2 NH 2), 36.18 (2C, CH 2 CH 2 CH 2 S) and 41.02 (2C, NH 2 CH 2 CH 2).
Journal of Raman Spectroscopy, 2014
In this study, we present surface-enhanced Raman spectroscopy (SERS) investigations of five analogs of a novel group of N-benzylamino(boronphenyl)methylphosphonic acids: N-benzylamino-(3-boronphenyl)-S-methylphosphonic acid (m-PhS), N-benzylamino-(4-boronphenyl)-S-methylphosphonic acid (p-PhS), N-benzylamino-(2-boronphenyl)-Rmethylphosphonic acid (o-PhR), N-benzylamino-(3-boronphenyl)-R-methylphosphonic acid (m-PhR), and N-benzylamino-(4boronphenyl)-R-methylphosphonic acid (p-PhR) deposited onto 10-nm gold nanoparticles in an aqueous solution at physiological pH (pH = 7). In addition, for the p-PhR molecule, the SERS spectra in the various conditions of pH levels of the solutions (from pH = 3 to 11) and phosphonic acid concentration (10 À3-10 À5 M) were measured. In general, the SERS spectral profiles indicate that at pH = 7, all of the aforementioned molecules interact with the colloidal gold surface via a boronphenyl ring. However, the orientation of the boronphenyl ring onto the substrate surface is different for each of the studied molecules. The boronic acid group of p-PhS and p-PhR binds to the gold nanoparticles, whereas the phosphonic acid group assists in the interaction with the substrate for p-PhR only. For all the molecules, the-C L C α (P)N-fragment distinctly influences the molecule/gold interactions, especially in the case of o-PhR. The previous differences in the compound behavior at the gold/liquid interface underline the role of an absolute configuration (-R and-S) and a type of isomer (orto-, meta-, and para-) on the SERS signals, which means their influence on the adsorbate geometry. Additionally, based on the SERS results for p-PhR in various environmental conditions, we draw conclusions about spectral changes (adsorbate geometry changes) as a result of the pH of solution and molecule concentration alternations.
Vibrational Spectroscopy, 2018
Functionalized n-alkanethiols such as 11-mercaptoundecanoic (MUA) and 3mercaptopropionic (MPA) acids are likely to adsorb in silver nanoparticles (AgNPs) solely through the thiol group (-SH) or also involving the carboxylate group (-COO-) in their structures. The relative tendency is closely related to pH conditions, solvent or the surface potential of the metallic nanoparticles. The SERS effect (Surface Enhancement Raman Scattering) was used for improving the understanding of MUA and MPA group interaction as well as the orientation of these organic compounds adsorbed on AgNPs and the influence of Cu(II) in solution. When analyzing the MPA SERS spectrum, it was verified that the thiol moiety was preferred to adsorb on the AgNPs surface in the thiolate form, presenting both anti and gauche conformations in both acidic and basic media. MUA SERS spectrum however, indicated that solely an anti conformation for the thiol moiety adsorbed on the AgNPs surface in both acidic and basic media. Adding Cu 2+ ion resulted in coordination to the carboxyl or carboxylate moieties was confirmed by the downshift of the band assigned to OCO stretching. The presence of Cu(II) increased the tendency of gauche conformation for MPA; the coordination of MUA to Cu(II) resulted in a more upright conformation of the carboxylic/carboxylate moieties in both acidic and basic media, respectively.
Colloids and Surfaces A, 2018
The purpose of the present work was to design a colorimetric method for the determination of 6-mercaptopurine (6-MP). 6-MP is a useful drug for the treatment of leukemia. Gold nanoparticles (NPs) are known to undergo a change in colour upon aggregation. Hence, in the present work phenylalanine-capped gold NPs were used as a colorimetric probe for the determination of 6-MP. Transmission electron microscopy (TEM) measurements revealed that the phenylalanine-capped gold NPs ranged from 6 to 9 nm in size. The UV-vis spectrophotometric measurements showed that the surface plasmon resonance (SPR) band of the metallic NPs was positioned at 516 nm. The effect of 6-MP addition on the SPR band of the gold NPs was investigated at pH 8 and 5. At pH 8, only a slight change in the position and intensity of the SPR band was observed. However, at pH 5, the SPR band of the gold NPs was broadened as well as red shifted in the presence of 6-MP. The colour of the gold NPs changed from red to dark purple. The ratio of the absorbance of the gold NPs at 600 and 516 nm versus the concentration of 6-MP was found to be linear in the range 0.2-1.8 μM. The limit of detection (LOD) of the colorimetric method for the determination of 6-MP was calculated to be 0.647 μM.
Malathion is widely used in agriculture due to their high efficiency as insecticides. They are very toxic hazardous chemicals to both human health and environment even at low concentration. The detection of pesticides (malathion) at the low levels developed by the environmental protection agency (EPA) still remains a challenge. A highly efficient fluorescent biosensor based on g-C3N4/AgNPs for AChE and malathion detection is successfully developed by impregnation method. The structural and morphological properties of the nanocomposites were characterized by using powder X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The analysis confirmed that there is a strong interfacial interaction between g-C3N4 and AgNPs. The fluorescent responses show an increase in intensity upon the additions of AChE which indicates that AChE as enzyme was hydrolyzing the substrate ACh, with the increase in oxidative electron as the preferred route of reaction. The developed OFF-ON sensor immobilizes by Actylcholestrase (AChE) and use as new probe for malathion detection. In the absence of malathion, AChE−g-C3N4/AgNCs exhibit high fluorescence intensity. However, the strong interaction of the basic sites to malathion, causes fluorescence quenching via static quenching and Ag form aggregation on the surface of g-C3N4. The experimental parameter such as pH of buffer (pH=6), concentration of acetylcholine (1 mM) and malathion (500 μM) were optimized. The sensor was also more sensitive with Stern-Volmer quenching constants (KSV) of 3.48x10 3 M-1. The practical use of this sensor for malathion determination in Khat was also demonstrated. The obtained amount of malathion in Khat is 168.8 μM.
Please cite this article as: V. Anbazhagan, K.B.A. Ahmed, S. Janani, Synthesis of catalytically active silver nanoparticles using lipid derived signaling molecule, N-Steroylethanolamine: promising antibacterial agent and selective colorimetric sensor for mercury ion, Sensors and Actuators B: Chemical (2014), http://dx.Abstract 22 A facile method was reported for preparing silver nanoparticles (AgNPs) based on 23 naturally occurring N-acylethanolamine (NAE) as a capping agent and sodium borohydride 24 as a reducing agent. NAEs have been found in the infracted areas of canine myocardium and 25 ischemic brain tissues. AgNPs prepared by N-steroylethanolamine (NSEA) are very stable 26 and can be reliably and reproducibly synthesized. These particles have a capability to 27 selective colorimetric sensing of the potentially hazardous Hg 2+ ion in water at micromolar 28 concentration. The proposed method was successfully employed for the determination of 29 Hg 2+ ion in blood plasma and also in various water bodies, such as tap water, pond water and 30 sewage water. Further, degradation of hazardous organic pollutant, methylene blue dye, was 31 explored using NSEA-AgNPs as catalyst. Besides selective sensing of Hg 2+ and degrading 32 hazardous dye, NSEA-AgNPs also shows excellent catalytic activity in the reduction of nitro 33 aromatics. In addition, NSEA-AgNPs shows bactericidal effect in Gram-positive and Gram 34 negative test bacteria, for which the values of minimum inhibitory concentration were 35 determined and reported. In summary, the NSEA-AgNPs reported in this work was a 36 promising candidate for versatile application, such as a sensor, antimicrobial and catalyst. 37 38 39 . 40