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Disulfide-induced self-assembled targets: A novel strategy for the label free colorimetric detection of DNAs/RNAs via unmodified gold nanoparticles

View Article: PubMed Central - PubMed

ABSTRACT

A modified non-cross-linking gold-nanoparticles (Au-NPs) aggregation strategy has been developed for the label free colorimetric detection of DNAs/RNAs based on self-assembling target species in the presence of thiolated probes. Two complementary thiol- modified probes, each of which specifically binds at one half of the target introduced SH groups at both ends of dsDNA. Continuous disulfide bond formation at 3′ and 5′ terminals of targets leads to the self-assembly of dsDNAs into the sulfur- rich and flexible products with different lengths. These products have a high affinity for the surface of Au-NPs and efficiently protect the surface from salt induced aggregation. To evaluate the assay efficacy, a small part of the citrus tristeza virus (CTV) genome was targeted, leading to a detection limit of about 5 × 10−9 mol.L−1 over a linear ranged from 20 × 10−9 to 10 × 10−7 mol.L−1. This approach also exhibits good reproducibility and recovery levels in the presence of plant total RNA or human plasma total circulating RNA extracts. Self-assembled targets can be then sensitively distinguished from non-assembled or mismatched targets after gel electrophoresis. The disulfide reaction method and integrating self-assembled DNAs/RNAs targets with bare AuNPs as a sensitive indicator provide us a powerful and simple visual detection tool for a wide range of applications.

No MeSH data available.


Schematic illustration of the overall colorimetric strategy based on unmodified AuNPs using disulfide induced self-assembling of DNA targets in the presence of left and right thiolated probes.
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f1: Schematic illustration of the overall colorimetric strategy based on unmodified AuNPs using disulfide induced self-assembling of DNA targets in the presence of left and right thiolated probes.

Mentions: To deal with these issues of concerns, the present study was designed with focuses on the development of a novel and simple strategy based on the use of thiolated primers and unmodified AuNPs for colorimetric detection of DNAs/RNAs targets. According to this strategy, frst the 3′- and 5′- thiol modified oligonucleotide probes simultaneously recognize their specific DNA targets on both tails. Next continuous disulfide bond formation at 3′ and 5′ terminals leads to the growth and self-assembly of dsDNA on both sides into the sulfur-rich supramolecular structures with different lengths. Mixing these products with an unmodified AuNPs solution was found to be resulted in shielded particles, which were more salt-tolerating than AuNPs linked to disulfide-interconnected probes (Fig. 1). In this regard, a facile colorimetric method for the detection of DNAs/RNAs in aqueous or biological samples by naked eye was achieved without time-consuming chemical modifications, expensive instruments and experienced operators. Additionally, the method was found to be sensitive to DNA nucleotide polymorphisms and the detection range could be tuned up by different concentrations of the probes. The viability of this simple colorimetric detection system was put to test through using it in the diagnosis of the Tristeza virus and miRNA 118 in plant total RNAs and human plasma circulating total RNA respectively.


Disulfide-induced self-assembled targets: A novel strategy for the label free colorimetric detection of DNAs/RNAs via unmodified gold nanoparticles
Schematic illustration of the overall colorimetric strategy based on unmodified AuNPs using disulfide induced self-assembling of DNA targets in the presence of left and right thiolated probes.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5384278&req=5

f1: Schematic illustration of the overall colorimetric strategy based on unmodified AuNPs using disulfide induced self-assembling of DNA targets in the presence of left and right thiolated probes.
Mentions: To deal with these issues of concerns, the present study was designed with focuses on the development of a novel and simple strategy based on the use of thiolated primers and unmodified AuNPs for colorimetric detection of DNAs/RNAs targets. According to this strategy, frst the 3′- and 5′- thiol modified oligonucleotide probes simultaneously recognize their specific DNA targets on both tails. Next continuous disulfide bond formation at 3′ and 5′ terminals leads to the growth and self-assembly of dsDNA on both sides into the sulfur-rich supramolecular structures with different lengths. Mixing these products with an unmodified AuNPs solution was found to be resulted in shielded particles, which were more salt-tolerating than AuNPs linked to disulfide-interconnected probes (Fig. 1). In this regard, a facile colorimetric method for the detection of DNAs/RNAs in aqueous or biological samples by naked eye was achieved without time-consuming chemical modifications, expensive instruments and experienced operators. Additionally, the method was found to be sensitive to DNA nucleotide polymorphisms and the detection range could be tuned up by different concentrations of the probes. The viability of this simple colorimetric detection system was put to test through using it in the diagnosis of the Tristeza virus and miRNA 118 in plant total RNAs and human plasma circulating total RNA respectively.

View Article: PubMed Central - PubMed

ABSTRACT

A modified non-cross-linking gold-nanoparticles (Au-NPs) aggregation strategy has been developed for the label free colorimetric detection of DNAs/RNAs based on self-assembling target species in the presence of thiolated probes. Two complementary thiol- modified probes, each of which specifically binds at one half of the target introduced SH groups at both ends of dsDNA. Continuous disulfide bond formation at 3′ and 5′ terminals of targets leads to the self-assembly of dsDNAs into the sulfur- rich and flexible products with different lengths. These products have a high affinity for the surface of Au-NPs and efficiently protect the surface from salt induced aggregation. To evaluate the assay efficacy, a small part of the citrus tristeza virus (CTV) genome was targeted, leading to a detection limit of about 5 × 10−9 mol.L−1 over a linear ranged from 20 × 10−9 to 10 × 10−7 mol.L−1. This approach also exhibits good reproducibility and recovery levels in the presence of plant total RNA or human plasma total circulating RNA extracts. Self-assembled targets can be then sensitively distinguished from non-assembled or mismatched targets after gel electrophoresis. The disulfide reaction method and integrating self-assembled DNAs/RNAs targets with bare AuNPs as a sensitive indicator provide us a powerful and simple visual detection tool for a wide range of applications.

No MeSH data available.