Colorimetric Detection of Melamine Based on Poly-Thymine Stabilized Gold Nanoparticles

A simple, fast and reliable colorimetric method for melamine detection based on gold nanoparticles (AuNPs) and poly-thymine (poly-T) is reported. Poly-T strands attract AuNPs through static electricity and keep them stable against aggregation in the presence of NaCl. The affinity between melamine and poly-T, hydrogen bond, frees AuNP from the protection provided by poly-T and thus makes AuNPs aggregate in the presence of NaCl. The color change of AuNPs from wine red to blue can be observed immediately by the naked eye during the aggregation process, and can be accurately recorded with the help of a UV/vis spetrophotometer within 5 minutes. The limit of detection (LOD) of melamine in pure water is 0.146 μmol/L with a linear range from 0.2×10-7 mol/L to 10.0×10-7 mol/L. In fresh milk and milk powder, the LOD is respectively as low as 2.37 μmol/L and 5.36 μmol/L.

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Highly Sensitive and Selective Colorimetric Detection of Methylmercury Based on DNA Functionalized Gold Nanoparticles

Sensors ◽

10.3390/s18082679 ◽

2018 ◽

Vol 18 (8) ◽

pp. 2679 ◽

Cited By ~ 6

Author(s):

Zheng-Jun Xie ◽

Xian-Yu Bao ◽

Chi-Fang Peng

Keyword(s):

Gold Nanoparticles ◽

Catalytic Activity ◽

Limit Of Detection ◽

Low Cost ◽

Colorimetric Detection ◽

Colorimetric Method ◽

Optimal Conditions ◽

Surface Deposition ◽

Highly Sensitive ◽

Dna Strand

A new colorimetric detection of methylmercury (CH3Hg+) was developed, which was based on the surface deposition of Hg enhancing the catalytic activity of gold nanoparticles (AuNPs). The AuNPs were functionalized with a specific DNA strand (HT7) recognizing CH3Hg+, which was used to capture and separate CH3Hg+ by centrifugation. It was found that the CH3Hg+ reduction resulted in the deposition of Hg onto the surface of AuNPs. As a result, the catalytic activity of the AuNPs toward the chromogenic reaction of 3,3,5,5-tetramethylbenzidine (TMB)-H2O2 was remarkably enhanced. Under optimal conditions, a limit of detection of 5.0 nM was obtained for CH3Hg+ with a linear range of 10–200 nM. We demonstrated that the colorimetric method was fairly simple with a low cost and can be conveniently applied to CH3Hg+ detection in environmental samples.

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DETERMINATION OF AMINOGLYCOSIDE ANTIBIOTICS BY A COLORIMETRIC METHOD BASED ON THE AGGREGATION OF GOLD NANOPARTICLES

NANO ◽

10.1142/s1793292013500379 ◽

2013 ◽

Vol 08 (04) ◽

pp. 1350037 ◽

Cited By ~ 4

Author(s):

RUIYONG WANG ◽

SHUMIN FAN ◽

RUIQIANG WANG ◽

RUI WANG ◽

HUANJING DOU ◽

...

Keyword(s):

Gold Nanoparticles ◽

Incubation Time ◽

Color Change ◽

Limit Of Detection ◽

Colorimetric Method ◽

Aminoglycoside Antibiotics ◽

Sensing Element ◽

Experimental Conditions ◽

Experimental Parameters

A sensitive and selective colorimetric biosensor for determination of gentamicin, amikacin and tobramycin was proposed with the unmodified gold nanoparticles (GNPs) as the sensing element. Gentamicin, amikacin and tobramycin can rapidly induce the aggregation of gold nanoparticles and is accompanied by a color change from red to blue. The concentration of gentamicin, amikacin and tobramycin can be determined by using UV-Vis spectrometer. The experimental parameters were optimized with regard to pH, incubation time and the concentration of the GNPs. Under optimal experimental conditions, the linear range of the colorimetric sensor for gentamicin/amikacin/tobramycin were 2.67–33.93 ng mL-1, 13.33–66.67 ng mL-1 and 20–180 ng mL-1, respectively. The corresponding limit of detection (3σ) was 0.354 ng mL-1, 0.999 ng mL-1 and 0.579 ng mL-1, respectively. This assay was simple and used to detect aminoglycoside antibiotics in milk and medicine products.

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Colorimetric detection of cysteine based on dispersion–aggregation mechanism of chitosan stabilized gold nanoparticles

Canadian Journal of Chemistry ◽

10.1139/cjc-2018-0258 ◽

2019 ◽

Vol 97 (3) ◽

pp. 233-237 ◽

Cited By ~ 1

Author(s):

Esther Jeyasekaran ◽

Sridevi Venkatachalam

Keyword(s):

Gold Nanoparticles ◽

High Selectivity ◽

Limit Of Detection ◽

Colorimetric Detection ◽

Colorimetric Method ◽

Colour Change ◽

Selective Detection ◽

Aggregation Mechanism ◽

Plausible Mechanism ◽

Sulfur Containing

A simple and selective colorimetric method for detection of cysteine using chitosan stabilized gold nanoparticles has been developed. L-cysteine is a sulfur containing amino acid. Cysteine binds with the gold nanoparticles through a sulfur group and induces aggregation of the nanoparticles, which leads to a visible colour change from pale red to blue. A good linearity was observed from 0.1 to 30 μmol/L (R = 0.9958) cysteine, and the limit of detection was found to be 0.1 μmol/L. The gold nanoparticles showed a high selectivity towards the detection of cysteine even in the presence of 10 000 fold higher concentration of common interferences such as glutathione, methionine, and homocysteine. A plausible mechanism for the selective detection of cysteine in presence of interferences based on a dispersion–aggregation mechanism has been proposed.

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Resorcinol Functionalized Gold Nanoparticles for Formaldehyde Colorimetric Detection

Nanomaterials ◽

10.3390/nano9020302 ◽

2019 ◽

Vol 9 (2) ◽

pp. 302 ◽

Cited By ~ 5

Author(s):

Carlos Martínez-Aquino ◽

Ana Costero ◽

Salvador Gil ◽

Pablo Gaviña

Keyword(s):

Gold Nanoparticles ◽

Color Change ◽

Limit Of Detection ◽

Colorimetric Detection ◽

Detection Mechanism ◽

Gas Phases ◽

Functionalized Gold Nanoparticles ◽

Composite Wood

Gold nanoparticles functionalized with resorcinol moieties have been prepared and used for detecting formaldehyde both in solution and gas phases. The detection mechanism is based on the color change of the probe upon the aggregation of the nanoparticles induced by the polymerization of the resorcinol moieties in the presence of formaldehyde. A limit of detection of 0.5 ppm in solution has been determined. The probe can be deployed for the detection of formaldehyde emissions from composite wood boards.

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pH Dependence on Colorimetric Detection of Hg2+ by Histidine-Functionalized Gold Nanoparticles

Indonesian Journal of Chemistry ◽

10.22146/ijc.51824 ◽

2020 ◽

Vol 20 (4) ◽

pp. 941

Author(s):

Dewi Eviane ◽

Dwi Siswanta ◽

Sri Juari Santosa

Keyword(s):

Gold Nanoparticles ◽

Color Change ◽

Ph Dependence ◽

Colorimetric Detection ◽

Trisodium Citrate ◽

Industrial Facility ◽

Naked Eye ◽

Functionalized Gold Nanoparticles ◽

Relative Standard ◽

Optimum Ph

In this study, we successfully developed gold nanoparticles capped with histidine (His-AuNPs) for Hg2+ detection using trisodium citrate as the reducing agent. The optimum pH for the detection of Hg2+ by His-AuNPs was 12. The addition of Hg2+ to the His-AuNPs caused the color change from red to black-blue, which is readily detectable by the naked eye. This color change is followed by a decrease in the intensity of the primary Surface Plasmon Resonance (SPR) peak at a wavelength (λ) of 525 nm and an increase in the secondary peak at λ = 650 nm. His-AuNPs effectively detected Hg2+ with limits of detection and quantitation of 1.77 µM and 5.89 µM, respectively. His-AuNPs exhibited good performance for the detection of Hg2+ in waste water collected from a steel industrial facility in Banten Province, with a recovery and a percent relative standard deviation of 115% and 1.02%, respectively.

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Naked-eye colorimetric detection of HCV RNA mediated by a 5′ UTR-targeted antisense oligonucleotide and plasmonic gold nanoparticles

The Analyst ◽

10.1039/d0an02481c ◽

2021 ◽

Author(s):

Almas Shamaila Mohammed ◽

Aniket Balapure ◽

Mahammad Nanne Khaja ◽

Ramakrishnan Ganesan ◽

Jayati Ray Dutta

Keyword(s):

Gold Nanoparticles ◽

Antisense Oligonucleotide ◽

Early Stage ◽

Colorimetric Detection ◽

Sensitive Detection ◽

Clinical Samples ◽

Hcv Rna ◽

Naked Eye

An Au NP based facile strategy for the rapid, early-stage, and sensitive detection of HCV RNA in clinical samples which avoids thiol tagging to the antisense oligonucleotide and expensive infrastructure is presented.

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A Simple Colorimetric Method for Naked-Eye Detection of Circulating Cell-Free DNA Using Unlabelled Gold Nanoparticles

ChemistrySelect ◽

10.1002/slct.201802671 ◽

2018 ◽

Vol 3 (41) ◽

pp. 11541-11551 ◽

Cited By ~ 3

Author(s):

Shweta Khanna ◽

Prasanta Padhan ◽

Sourav Das ◽

Kumar Sagar Jaiswal ◽

Archana Tripathy ◽

...

Keyword(s):

Gold Nanoparticles ◽

Colorimetric Method ◽

Eye Detection ◽

Cell Free Dna ◽

Naked Eye ◽

Free Dna ◽

Naked Eye Detection ◽

Circulating Cell Free Dna

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Naked-Eye Detection of Mercury Ions from Morphological Transition of Silver Nanocubes: Tuning Sensitivity Using Co-Staining Agent

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.19069 ◽

2021 ◽

Vol 21 (4) ◽

pp. 2123-2131

Author(s):

Alagan Jeevika ◽

Dhesingh Ravi Shankaran

Keyword(s):

Color Change ◽

Limit Of Detection ◽

Low Cost ◽

Toxic Metal ◽

Face Centered Cubic ◽

Mercury Ions ◽

Eye Detection ◽

Naked Eye ◽

Silver Nanocubes ◽

Naked Eye Detection

A simple, low-cost and highly selective nanosensor was developed for naked-eye detection of mercury ions (Hg2+) based on Eosin/silver nanocubes (Eosin/AgNCbs). Silver nanocubes (AgNCbs) were synthesized by polyol assisted chemical method. HR-TEM result shows the formed AgNCbs have a mean diameter of 84±0.005 nM (diagonally measured) and edge length of 55±0.01 nM. XRD result confirms that the AgNCbs are single crystalline in nature with a phase structure of face centered cubic (FCC) of silver. On interaction of Hg2+, AgNCbs exhibits a color change from gray to black up to 16.67 μM of Hg2+ owed to the formation of solid like bimetallic complex of Ag/Hg amalgam. The selectivity of AgNCbs was evaluated with several other toxic metal ions including, Mg2+, Ba2+, Ca4+, Pb2+, Cd4+, Zn2+, Co2+, Cu2+, K+ and Ni2+ and found good selectivity towards Hg2+. The sensitivity of the AgNCbs sensor system was tuned by using Eosin as a co-staining agent. The Eosin/AgNCbs showed a limit of detection of 60±0.050 nM with the color change from orange to purple. The results suggests that the Eosin/AgNCbs nanosensor exhibits good selectivity, sensitivity, repeatability and rapid response, which could be explored for real-time detection of Hg2+ in environmental and biological samples.

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