Rapid identification of bacteria and yeast using surface‐enhanced Raman scattering

Abstract

Surface-enhanced Raman scattering (SERS) is a powerful technique used for obtaining chemical information about the moleculesand molecular structures in the vicinity of surfaces of noble metal nanostructures. The chemical information acquired through SERS can be used for not only characterization but also detection and identification. In a clinical setting, rapid and accurate identification of micro-organisms is critical. The biochemical information collected through the SERS spectra can be used for quick identification of micro-organisms. The concentrated silver colloidal nanoparticles (AgNPs) are simply mixed with micro-organisms after culturing, and their SERS spectra acquired. Since the nanoparticles are in contact with the cell wall of the micro-organism, the biochemical information obtained is mostly assumed as originating from the cell wall which the AgNPs are in contact with, and is considered as the 'fingerprint' of the micro-organism, which can be used for the identification. Since a SERS spectrum can be acquired only in seconds, the obtained spectrum can be used for fast micro-organism identification. The reproducibility of the spectra obtained from micro-organisms is first tested, and then the obtained spectra are used for the goal. The identification of micro-organisms in mixtures is also attempted in model mixtures. It is demonstrated that the SERS can be used for fast and accurate identification of micro-organisms such as bacteria and yeast, even in their mixtures. Four bacteria, i.e. Shigella sonnei, Erwinia amylovara, Proteus vulgaris and DH5α (E. coli strain), and three yeast cells, i.e. Hyphopichia burtonii, Candida parapsilosis and Filobasidiella neoformans are used as model micro-organisms in the study.

Plataformas nanoestructuradas de plata para identificación cualitativa de Escherichia coli mediante espectroscopia Raman intensificada por efecto de superficie “prueba de concepto del sistema”

“…A pesar de que existen numerosos reportes sobre la determinación de bacterias utilizando la técnica SERS mediante el uso de nanopartículas de metales nobles en solución [14], en la literatura revisada no encontramos publicaciones que reporten el uso de plataformas nanoestructuradas sólidas de plata para detección de E. coli. La determinación de bacterias patógenas es de vital importancia para la salud pública, debido a que cada día es necesaria la búsqueda de nuevos sistemas de detección con diagnósticos oportunos que permitan obtener una respuesta rápida y confiable de un analito en particular.…”

“…En estudios similares este modo de vibración es utilizado como huella digital para la determinación e identificación de E. coli [ 7,14]. Otros modos de vibración importantes presentes en el espectro SERS están relacionados con la presencia de lípidos y ácidos nucleicos presentes en la estructura de E. coli [15].…”

IR and Raman Spectroscopy for Pathogen Detection

“…By applying different SERS substrates, numerous groups have shown that SERS spectra of different bacterial species show different spectral features, which allows the qualitative differentiation of the species by their SERS spectra [113,117,120,124,126,[128][129][130][131][132][133][134][135][136][137][138][139][140]. The range of the investigated bacteria comprises Gram-positive as well as Gram-negative bacteria.…”

“…They could even discriminate three strains of E. coli from each other by simple PCA classification [130]. Some groups have investigated mixed bacterial samples and were able to tell them apart from pure cultures by PCA [130,143] or Euclidian distance [128,129]. Surprisingly, the mixed samples did not appear in the area between the pure samples but were shifted toward one constituent of the mixture [129,143] or even showed larger difference from both original components [128,130].…”

Surface-Enhanced Raman Scattering as an Emerging Characterization and Detection Technique

“…However, the several issues inherent to the nature of the technique, mainly reproducibility, still persist and lower the applicability to its wide spread use in biological applications. The detection and identification of several biological molecules such as proteins [106][107][108][109][110], DNA [111][112][113][114], and RNA [115,116] and molecular organizations such as bacteria [117][118][119][120][121][122][123][124][125][126], yeast [127][128][129], and viruses [130,131] using SERS were reported. The detection scheme could be based on either using the intrinsic fingerprint information of the molecules or molecular structures or the use of an external label.…”