Improved antireflection coated microspheres for biological applications of optical tweezers

Valentina Ferro*, Aaron Sonnberger, Mohammad K. Abdosamadi, Craig McDonald, Erik Schäffer, David McGloin

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingPublished conference contribution

2 Citations (Scopus)


The success of optical tweezers in cellular biology1 is in part due to the wide range of forces that can be applied, from femto- to hundreds of pico-Newtons; nevertheless extending the range of applicable forces to the nanoNewton regime opens access to a new set of phenomena that currently lie beyond optical manipulation. A successful approach to overcome the conventional limits on trapping forces involves the optimization of the trapped probes. Jannasch et al.2 demonstrated that an anti-reflective shell of nanoporous titanium dioxide (aTiO2, nshell = 1.75) on a core particle made out of titanium dioxide in the anatase phase (cTiO2, ncore = 2.3) results in trappable microspheres capable to reach forces above 1 nN. Here we present how the technique can be further improved by coating the high refractive index microspheres with an additional anti-reflective shell made out of silica (SiO2). This external shell not only improves the trap stability for microspheres of different sizes, but also enables the use of functionalization techniques already established for commercial silica beads in biological experiments. We are also investigating the use of these new microspheres as probes to measure adhesion forces between intercellular adhesion molecule 1 (ICAM-1) and lymphocyte function-associated antigen 1 (LFA-1) in effector T-Cells and will present preliminary results comparing standard and high-index beads.

Original languageEnglish
Title of host publicationProceedings: Optical Trapping and Optical Micromanipulation XIII
EditorsKishan Dholakia, Gabriel C. Spalding
ISBN (Electronic)9781510602359
Publication statusPublished - 16 Sept 2016
EventOptical Trapping and Optical Micromanipulation XIII - San Diego, United States
Duration: 28 Aug 20161 Sept 2016


ConferenceOptical Trapping and Optical Micromanipulation XIII
Country/TerritoryUnited States
CitySan Diego

Bibliographical note

Publisher Copyright:
© 2016 SPIE.


  • Antireflection coating
  • Cellular Adhesion
  • Optical tweezers
  • T lymphocytes


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