Reproducible surface-enhanced Raman scattering spectra of bacteria on aggregated silver nanoparticles

Mehmet Kahraman, M. Müge Yazici, Fikrettin Şahin, Ömer F. Bayrak, Mustafa Çulha

Research output: Contribution to journalArticlepeer-review

104 Scopus citations


Surface-enhanced Raman scattering (SERS) is proven to be a powerful technique for rapid identification and discrimination of microorganisms. However, due to the heterogeneous nature of the samples, the acquisition of reproducible spectra hinders the further development of the technique. In this study, we demonstrate the influence of the experimental conditions on SERS spectra. Then, we report a simple sample preparation method coupled with a light microscope attached to a Raman spectrometer to find a proper spot on the sample to acquire reproducible SERS spectra. This method utilizes the excited surface plasmons of the aggregated silver nanoparticles to visualize the spots on the sample. The samples are prepared using the concentrated silver colloidal solutions. The collection time for one spectrum is 10 s and each spectrum is a very good representative of the other spectra acquired from the same sample. The nature of the surface charge of the silver nanoparticles influences the spectral features by determining the strength of the interactions between nanoparticles and bacteria and the aggregation properties of the nanoparticles. Although increasing the colloid concentration in the sample resulted in reproducible spectra from arbitrary points on the sample, a great variation from sample to sample prepared with the different colloidal solution concentrations is observed.

Original languageEnglish (US)
Pages (from-to)479-485
Number of pages7
JournalApplied Spectroscopy
Issue number5
StatePublished - May 2007
Externally publishedYes


  • Bacteria
  • Colloid
  • Nanoparticle
  • Plasmon
  • Raman scattering
  • SERS
  • Surface-enhanced Raman scattering

ASJC Scopus subject areas

  • Instrumentation
  • Spectroscopy


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