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Title: Precipitation of PEG/Carboxyl-modified gold nanoparticles with magnesium pyrophosphate : a new platform for real-time monitoring of loop-mediated isothermal amplification
Authors: Qin, AL 
Fu, LT 
Wong, JKF 
Chau, LY 
Yip, SP 
Lee, TMH 
Keywords: DNA detection
Isothermal amplification
Real-time LAMP
Gold nanoparticles
Magnesium pyrophosphate
Precipitation-based readout
Point-of-care nucleic acid testing
Issue Date: 2017
Publisher: American Chemical Society
Source: ACS applied materials and interfaces, 2017, v. 9, no. 12, p. 10472-10480 How to cite?
Journal: ACS applied materials and interfaces 
Abstract: Gold nanoparticles have proven to be promising for decentralized nucleic acid testing by virtue of their simple visual readout and absorbance-based quantification. A major challenge toward their practical application is to achieve ultrasensitive detection without compromising simplicity. The conventional strategy of thermocycling amplification is unfavorable (because of both instrumentation and preparation of thermostable oligonucleotide-modified gold nanoparticle probes). Herein, on the basis of a previously unreported co-precipitation phenomenon between thiolated poly(ethylene glycol)/11-mercaptoundecanoic acid co-modified gold nanoparticles and magnesium pyrophosphate crystals (an isothermal DNA amplification reaction byproduct), a new ultrasensitive and simple DNA assay platform is developed. The binding mechanism underlying the co-precipitation phenomenon is found to be caused by the complexation of carboxyl and pyrophosphate with free magnesium ions. Remarkably, poly(ethylene glycol) does not hinder the binding and effectively stabilizes gold nanoparticles against magnesium ion-induced aggregation (without pyrophosphate). In fact, a similar phenomenon is observed in other poly(ethylene glycol)- and carboxyl-containing nanomaterials. When the gold nanoparticle probe is incorporated into a loop-mediated isothermal amplification reaction, it remains as a red dispersion for a negative sample (in the absence of a target DNA sequence) but appears as a red precipitate for a positive sample (in the presence of a target). This results in a first-of-its-kind gold nanoparticle-based DNA assay platform with isothermal amplification and real-time monitoring capabilities.
ISSN: 1944-8244
EISSN: 1944-8252
DOI: 10.1021/acsami.7b00046
Rights: © 2017 American Chemical Society
This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
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The following definitive published versions Qin, A., Fu, L. T., Wong, J. K., Chau, L. Y., Yip, S. P., & Lee, T. M. (2017). Precipitation of PEG/Carboxyl-Modified Gold Nanoparticles with Magnesium Pyrophosphate: A New Platform for Real-Time Monitoring of Loop-Mediated Isothermal Amplification. ACS Applied Materials & Interfaces, 9(12), 10472-10480 is available at
The ACS Applied Materials and Interfaces is available at
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