Gold Nanostars Surface Enhanced Raman Spectroscopy (SERS) DNABiosensor forTB Detection

Abstract

Background: Surface Enhanced Raman Spectroscopy is a potent and unique spectroscopy technique for ultrasensitive sensing and trace detection of analyte adsorbed on the SERS substrate. Light driven technologies have contributed to improving the quality of life for centuries therefore an optical biosensor based on SERS technology using nanostructures as potential SERS substrate can be an effective, portable and sensitive analytical device for rapid diagnosis of infectious diseases. In current study, the potential of gold nanostars to exhibit high SERS spectra and ultra sensitive detection against the target analyte (TB DNA) was evaluated. Methodology: Gold nanostars were synthesized using seed mediated protocol and were characterized using UV-Vis spectroscopy and scanning electron microscope (SEM). MPTMS functionalized glass slides were coated with gold nanostars where thiol groups served as linkage moieties for immobilization process. Afterwards, single stranded thiolated DNA probes were drop casted onto the gold nanostars adsorbed glass slides. Eventually, SERS analysis was performed for the target (TB DNA) and non-target analyte (E.coli DNA) alongwith control group (without SERS substrate) to analyze the sensitivity of the sensor and for comparative analysis respectively. Results: UV-Vis analysis revealed the distinct peak at 664nm attributed to gold nanostars whereas SEM analysis demonstrated the characteristic morphology of gold nanostars with sharp tips and branches. FTIR spectra of functionalized glass slides confirmed the glass coating via MPTMS through the presence of C-H bending, a characteristic of MPTMS. SERS spectra analysis against the target DNA resulted in high Raman intensity in comparison to non-target analyte (E.coli DNA) and control thereby successfully demonstrating the specificity and sensitivity of our SERS biosensor. Conclusion: These findings suggest that gold nanostars serve as a potential substrate for the development of SERS based biosensors for more rapid, robust, specific and ultra-sensitive detection hallmark against and can be used for generating even more potent and versatile SERS sensors in the future.