25 research outputs found
Direct colorimetric diagnosis of pathogen infections by utilizing thiol-labeled PCR primers and unmodified gold nanoparticles
No full textWe describe here a greatly simplified colorimetric detection method to identify PCR-amplified nucleic acids. Our method relies on the PCR product having thiol group at one end, which is generated by employing thiolated PCR primer. After PCR amplification reaction, unmodified gold nanoparticles (AuNPs) are added into the reaction tube followed by the addition of NaCl to induce the aggregation of AuNPs. The PCR products strongly bind to the surface of AuNPs through the interaction of the terminal thiol groups and the long chain of DNA which has abundant negative charges enhances the electrostatic and steric repulsion among AuNPs, which consequently leads to the prevention of the salt-induced aggregation. As a result, the color of AuNPs remains red in the presence of the PCR-amplified nucleic acids, while the AuNPs change its color from red to blue due to the salt-induced aggregation in the absence of the PCR products. This simple but very efficient colorimetric strategy was successfully demonstrated by diagnosing Chlamydia infection using a real human urine sample. Since the results can be clearly seen with the naked eye without any complicated step such as surface modification of AuNPs or PCR product purification, this method can be easily applied to point-of-care diagnosis. (c) 2010 Elsevier B.V. All rights reserved.This work was supported by the National Research Foundation
of Korea (NRF) grant funded by the Korea government (MEST) (No.
2009-0080602 and No. R01-2007-000-11851-0), the Brain Korea
21 (BK21) Project, and the Center for Ultramicrochemical Process
Systems (CUPS).
An anisotropic snowflake-like structural assembly of polymer-capped gold nanoparticles
No full textSnowflake-like structural assembly of isotropic gold nanoparticles (GNPs) is reported. A modified polyamine method has been employed to synthesize positively charged GNPs in presence of a polymeric metaphosphate. This process yields fascinating dendritic self-assembled morphologies. Structural characterization revealed that there was aggregation of crystalline GNPs. The aggregates of GNPs formed in the initial stage of synthesis are assumed to act as the bulging seeds for final growth of complex morphologies at nanometer to micrometer length scale. Self-assembly of GNPs was found to be greatly influenced by the concentration of gold precursor. Diffusion limited aggregation of GNPs is suggested as the plausible mechanism for this nanoparticle self-organization process.Financial support for this investigation
was provided by Basic Science Research Program through the
National Research Foundation of Korea (NRF) funded by the
Ministry of Education, Science and Technology (MOST, No.
2009-008-0602 & No. R01-2007-000-11851-0) and the Brain
Korea 21 (BK21) program
A gold nanorod-based optical DNA biosensor for the diagnosis of pathogens
No full textA novel optical biosensor for detecting target DNA, utilizing gold nanorods (GNRs) as molecular probes is demonstrated. This sensor is based on simultaneous biorecognition-mediated hybridization of target DNA in a sandwich type manner with two different capture probe DNA sequences modified separately with identical sets of GNRs, which leads to aggregation of GNRs. The hybridization induced aggregation as revealed by TEM analysis, promotes the modulation of surface plasmon resonance of GNRs, which forms the basis of complementary target DNA detection from the Chlamydia trachomatis pathogen. Thermally induced reversible dissociation of hybridized DNA is demonstrated by melting analysis. The present sensing strategy is successfully demonstrated by detecting PCR amplified C. trachomatis pathogen gene isolated from human urine sample in a concentration range of 0.25-20 nM. Furthermore, this sensor displays excellent specificity by discriminating the target DNA versus other non-specific pathogenic genes. (C) 2010 Elsevier B.V. All rights reserved.This work was supported by National Research Foundation of
Korea (NRF) grant funded by the Korea government (MEST) (No.
2009-0080602 and No.R01-2007-000-11851-0) and Brain Korea 21
(BK21) program.
Label free colorimetric detection of sequence specific Chlamydia Trachomatis DNA using gold nanorods
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Gold nanoparticles-based colorimetric single nucleotide polymorphisms detection utilizing allele-specific PCR
No full textGold nanoparticles - Based colorimetric single nucleotide polymorphisms genotyping utilizing allele-specific PCR
No full textSimple colorimetric detection of single nucleotide polymorphisms using unmodified gold Nanoparticles
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Colorimetric galactose sensor using nanofactory entrapping magnetic nanoparticles as peroxidase mimetics and galactose oxidase
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