Optical measurements of dynamic adhesive forces between bacteria and protein-coated surfaces

Kathryn Simpson, Gabriela Bowden, Magnus Höök, Bahman Anvari

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


Bacterial adhesion to host tissue is an initial step in the infectious process. Staphylococcus aureus, a major human pathogen, has covalently anchored cell surface adhesins called microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) which mediate specific adhesion to extracellular matrix (ECM) molecules. Understanding MSCRAMM binding is potentially useful in developing effective antibacterial drugs. In this study, optical tweezers were used in conjunction with a quadrant photodetector to measure adhesive forces between MSCRAMMs and surfaces coated with the ECM molecule fibronectin. Using a piezoelectrically driven stage, a fibronectin-coated microsphere adherent to a coverslip was brought into contact with a cell optically trapped at 830 nm. The microsphere was subsequently moved away from the cell, and a quadrant photodiode monitored the cell displacement from the trap center during the detachment process. The photodetector voltage signals were subsequently converted into the adhesive forces between MSCRAMMs and fibronectin based on a calibration using Stoke's law for viscous drag. Optical detection of the trapped bead displacement allowed us to study both the dynamics of the detachment process and observe the effects of various loading rates. This technique can be extended to identify the contributions of various MSCRAMM domains to adhesion in order to develop new methods of treating infections.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
EditorsD.V. Nicolau, J Enderlein, R.C. Leif, D.L. Farkas
Number of pages8
StatePublished - 2003
EventManipulation and Analysis of Biomolecules, Cells , and Tissues - San Jose, CA, United States
Duration: Jan 28 2003Jan 29 2003


OtherManipulation and Analysis of Biomolecules, Cells , and Tissues
Country/TerritoryUnited States
CitySan Jose, CA


  • Bacterial adhesion
  • Biofilm
  • Extracellular matrix
  • Infection
  • Staphylococcus aureus
  • Unbinding force

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics


Dive into the research topics of 'Optical measurements of dynamic adhesive forces between bacteria and protein-coated surfaces'. Together they form a unique fingerprint.

Cite this