Development of a DNA-based aptasensor for rapid detection of tuberculosis

Abstract

This project focuses on the development of a portable DNA-aptamer based biosensor, which is referred to as an aptasensor, that would aid in the diagnosis of the highly contagious disease tuberculosis. An important aspect of this project is to obtain a signal for DNA using electrochemical surface-enhanced Raman spectroscopy (E-SERS), with an aptamer used to bind specific biomarkers for detection. This method was used to detect the signal of DNA bases, nucleotides, and an oligonucleotide. Screen printed electrodes modified with silver colloidal nanoparticles were immersed in the DNA base and nucleotide solutions. A voltage was applied varying from 0.0 to -1.0V. These experiments showed that DNA components can be detected using E-SERS. Several molecules were tested as possible choices for backfilling, in order to prevent surface denaturation of the DNA and to reduce non-specific binding. Signal was detected for the aptamer (referred to as probe 1), and hybridization studies between probe 1 and its complimentary sequence, target 1, were successful using 12-mercaptododecanoic acid as the backfilling spacer. The limit of detection for the target on the SERS substrate used was found to be approximately 0.4 mM. The ds-DNA TB oligo was weakly detected after the modification of the AgNP electrode using 0.5 M KCl. These results indicate that a SERS-based aptasensor has great potential in the field of rapid diagnostics.