Colorimetric biosensing of targeted gene sequence using dual nanoparticle platforms

Abstract

We have developed a colorimetric biosensor using a dual platform of gold nanoparticles and graphene oxide sheets for the detection of Salmonella enterica. The presence of the invA gene in S. enterica causes a change in color of the biosensor from its original pinkish-red to a light purplish solution. This occurs through the aggregation of the primary gold nanoparticles–conjugated DNA probe onto the surface of the secondary graphene oxide–conjugated DNA probe through DNA hybridization with the targeted DNA sequence. Spectrophotometry analysis showed a shift in wavelength from 525 nm to 600 nm with 1 μM of DNA target. Specificity testing revealed that the biosensor was able to detect various serovars of the S. enterica while no color change was observed with the other bacterial species. Sensitivity testing revealed the limit of detection was at 1 nM of DNA target. This proves the effectiveness of the biosensor in the detection of S. enterica through DNA hybridization.

Keywords:

• biosensor
• DNA hybridization
• DNA probe
• gold nanoparticles
• graphene oxide
• Salmonella enterica

Acknowledgments

We thank the University of Malaya for the facilities and funding provided for this particular research project through the Postgraduate Research Grant (PV039-2011A), University of Malaya Research Grant (UMRG) program (RP007C/13AFR), and the Molecular Diagnostics of Bacteria grant (GA0103-2013). We also thank the Ministry of Higher Education of Malaysia for its financial support through the High Impact Research Grant (UM.C/1/625/HIR/MOHE/05).

Disclosure

The authors report no conflicts of interest in this work.