Measurement of adhesive forces between bacteria and protein-coated surfaces using optical tweezers

Kathryn H. Simpson, Gabriela Bowden, Magnus Höök, Bahman Anvari

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


Bacterial adhesion is a primary cause of failure in implanted medical devices. Bacteria commonly found in device-related infections, such as S. aureus, have multiple cell surface adhesins which mediate specific adhesion to molecules found in extracellular matrix and blood plasma. Adhesins recognizing fibrinogen, fibronectin, collagen, and elastin molecules have been isolated in S. aureus. We have used optical tweezers to measure the adhesive force between a single bacterium and a protein-coated surface. Various concentrations of fibronectin, fibrinogen, or whole plasma were immobilized onto 10-μm diameter polystyrene microspheres. We optically trapped a bacterium with a titanium-sapphire laser tuned to 830 nm and contacted the cell with a coated bead. We determined the minimum force necessary to separate the cell and bead. For beads coated with fibronectin and fibrinogen, detachment force values occurred as approximate integer multiples of an estimated single bond detachment force. With plasma-coated beads, only cells lacking the fibrinogen adhesin could be detached; therefore, we believe that either this adhesin is prevalent on wild-type cells, or it is preferentially adsorbed onto the beads. Additionally, the whole plasma detachment forces appeared random; therefore, we believe that many adhesins participate in bonding to plasma.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
EditorsD.L. Farkas, R.C. Leif
Number of pages8
StatePublished - 2002
EventOptical Diagnostics of Living Cells V - San Jose, CA, United States
Duration: Jan 23 2002Jan 25 2002


OtherOptical Diagnostics of Living Cells V
Country/TerritoryUnited States
CitySan Jose, CA


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

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics


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