Taking microcavity label-Free single molecule detection deep into the protein realm: Cancer marker detection at the ultimatesensitivity

Stephen Arnold, Stephen Holler, Xudong Fan

Research output: Chapter in Book/Report/Conference proceedingChapter


Finding a method for label-free sensing of individual bio-nanoparticles is considered the “Holy Grail” in the bio-sensing field. An ideal technology that could do this would be able to follow the sensing of biological antigen-antibody interactions in their native form and in real-time without interfering tags. It has been over 10 years since the possibility of label-free microcavity detection of single virus or single protein binding by a reactive frequency shift was theorized, and over 5 years since the non-specific detection and sizing of Influenza A (InfA) was demonstrated using this mechanism. The signal to noise ratio in that experiment was only 3. Detecting the smallest virus MS2 with a mass only one hundredth of InfA, therefore seemed hopeless. The prospect of detecting an intermediate size protein such BSA was anticipated to be even further out of reach, since its mass is 5,000× smaller than InfA. However, within the last 2 years both were detected with an extraordinary microcavity that marries micro-cavity photonics with nano-plasmonic receptors. The following article chronicles this advance.

Original languageEnglish (US)
Title of host publicationNano-Structures for Optics and Photonics
Subtitle of host publicationOptical Strategies for Enhancing Sensing, Imaging, Communication and Energy Conversion
PublisherSpringer Netherlands
Number of pages14
ISBN (Electronic)9789401791335
ISBN (Print)9789401791328
StatePublished - Jan 1 2015


  • BSA
  • Biosensing
  • Bovine serum albumin
  • Cancer marker
  • Gold nanoshell
  • LSP
  • Label-free single molecule detection
  • Microcavity
  • Microresonator
  • Plasmonic enhancement
  • Plasmonic epitope
  • Reactive sensing principle
  • Ring resonator
  • Single molecule detection
  • Smallest virus
  • Thyroglobulin
  • WGM
  • WGM-nanoplasmonic-hybrid resonator
  • WGM-nph
  • Whispering gallery mode

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology
  • General Engineering
  • General Physics and Astronomy


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