Rapid Detection of Staphylococcus aureus Genomic DNA Using Peptide Nucleic Acid and Gold Nanoparticles
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Date
2016-10
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Council of the National Academy of Sciences
Abstract
Staphylococcus aureus is a Gram-positive bacterium
and is known to affect almost all mammalian species.
This organism causes a multitude of cutaneous and
systemic human diseases and is the main etiological agent
in causing bovine mastitis causing heavy economic loss to
dairy industry. Microbiological detection of S. aureus is
time consuming and molecular diagnostic technique
requires skilled personnel and costly equipment. Peptide
nucleic acids (PNA) are DNA analogues with charged
neutral polyamide backbone. Free PNA induces aggregation
of citrate capped colloidal gold nanoparticles. Using
this property of PNA, rapid, simple, and an easy method of
detecting S. aureus genomics was developed in the present
study. PNA concentration of 1 lM induced clear colour
change of gold nanoparticles from brick red to blue colour.
Visual detection limit of complementary target DNA
inhibiting PNA induced agglomeration of gold nanoparticles
was 0.25 lM whereas, spectral detection limit was
even at lower concentration of 0.1 lM. PNA induced
aggregation was gradually reduced with increasing concentration
of non-complementary DNA and concentration
of non-complementary DNA of 2.5 times more than PNA
concentration was able to prevent the PNA induced
aggregation of gold nanoparticles. Sensitivity detection
limit of this colorimetric assay in detecting genomic DNA
of S. aureus was 106 cells visually and 104 cells spectrophotometrically.
The test was performed with 20 field
isolates of staphylococcal species. Out of 20 isolates, 16
were identified as S. aureus specifically. This assay was
robust and had the advantage of being simple, fast and
sensitive.
Description
TNV_PNAS_2016_Oct
Keywords
Veterinary Science