(Invited) Plasma-Synthesized Coupled Nanoplasmonic Gold for DNA Sersing

Abstract

The facilitated electrochemical properties of plasma play a critical role in enhancing the synthesis and design of functional nanomaterials for the development of novel sensors. The targeted challenge is to customize and tailor functionality at multiple scales to improve detection device performance. In the realm of optoelectronics, plasmonic sensing is considered an efficient tool for investigating molecular properties, often accompanied by Raman, FTIR or Fluorescent spectroscopy. Specifically, Raman scattering, also known as SERS (surface-enhanced Raman scattering), is commonly used to probe analytes at a reduced scale using plasmonic enhancers. This technique is especially useful for rapidly and accurately investigating biologically relevant samples, such as DNA and RNA. DNA/RNA-related investigations are crucial in modern nanomedicine due to the progress made in bionanotechnology, DNA vaccines, and functional gene engineering. DNA, in particular, is highly valued by microbiologists because it contains information about the nature of bio-species. Currently, PCR-related methods dominate the field for molecular-sensitive DNA-level studies, but it is challenging to investigate using optical techniques like SERS. Despite its promise, SERS still requires technological and analytical improvements. A sophisticated plasmonic nanomaterial provides considerably improved photon scattering due to the strongly localized field confinement effect, resulting in better performance. In this report, a nanoplasmonic sensor was designed using a plasma-driven electrochemical reduction mechanism, achieved through an atmospheric pressure He-plasma jet setup operating at kHz frequency. The reactive oxidative species donated electrons via liquid-gas electrochemistry towards the Ar-delivered Au(3+)-containing microdroplets, resulting in microscaled aggregates composed of AuNPs obtained from the nebulized ionic gold liquid precursor. Due to the strong coupling between nanoparticles, a high analytical enhancement factor of about 107 was achieved, and the substrate enabled obtaining Raman fingerprints of bacterial DNA fragments (M. luteus and S. aureus, E. coli, J. lividum) at nanovolume sample quantities. Additionally, the main DNA molecular vibrational signatures associated with nucleobase motions were extracted from the collected spectra and used to reliably classify bacterial strains using statistical principal component analysis.[1] References[1] Shvalya, V., Vasudevan, A., Modic, M., Abutoama, M., Skubic, C., Nadižar, N., ... & Cvelbar, U. (2022). Bacterial DNA Recognition by SERS Active Plasma-Coupled Nanogold. Nano Letters.