Manipulation of silver nanoparticles in a droplet for label-free detection of biological molecules using surface-enhanced Raman scattering

Mustafa Çulha, Mine Altunbek, Sercan Keskin, Deniz Saatçi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

8 Scopus citations


Detection and identification of biomacromolecules is of critical importance in many fields ranging from biotechnology to medicine. Surface-enhanced Raman scattering (SERS) is an emerging technique for the label-free detection and identification of biological molecules and structures with its fingerprinting properties and high sensitivity. However, there are a number of obstacles for its applications for biological macromolecules due to their complexity. In this report, manipulation of microscopic processes in play during the drying of a sessile droplet as a tool to influence the nanoparticle-macromolecule packing, which has dramatic effect on SERS performance, before the SERS acquisition is demonstrated. A process known as the coffee ring phenomenon jams all particles and molecular species to the edges of the droplet during drying. This uncontrolled process has dramatic effects on a SERS experiment, using colloidal metal nanoparticles as substrates, by sweeping everything to the edges and influencing the packing of nanoparticles in the droplet area. A plastic tip was dipped into a drying sample droplet to influence the uncontrolled piling up. A negatively-charged protein, BSA, a positively-charged protein, cytochrom c, and a 20-base long oligonucleotide, were used as model biomacromolecules in this study. While a minimum of one order of magnitude lower concentration improvement in detection limit was observed with negatively-charged biomacromolecules, no significant improvement was observed with positively-charged ones compared to a sample droplet left on the surface without any interference. With the demonstrated approach, picomolar-level biomolecular detection using SERS is possible.

Original languageEnglish (US)
Title of host publicationPlasmonics in Biology and Medicine VIII
StatePublished - 2011
Externally publishedYes
EventPlasmonics in Biology and Medicine VIII - San Francisco, CA, United States
Duration: Jan 23 2011Jan 24 2011

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


ConferencePlasmonics in Biology and Medicine VIII
Country/TerritoryUnited States
CitySan Francisco, CA


  • Biomacromolecules
  • Contact line pinning
  • Detection
  • Proteins
  • SERS

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging


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