NanoTracker™ 2 - designed for quantitative force measurements

The NanoTracker™ 2 is an optical tweezers platform based on research-grade inverted optical microscopes and designed for sensitive manipulation, force and tracking experiments. With the NanoTracker™ 2, the user can trap and track particles from several µm down to 30nm with the ability to control, manipulate and observe samples in real time with nanometer precision and femtoNewton resolution.

NanoTracker™ technology provides precisely quantifiable and reproducible measurements of particle/cell interactions. The system delivers precise information about single molecule mechanics and may also be used to determine mechanical characteristics such as adhesion, elasticity or stiffness on single molecules.

The video shows confocal scanning microscopy combined with optical particle manipulation

Highest performance & modular design

The new system is designed to detect the smallest forces and manipulate particles or molecules with the highest precision. Special laser stabilization and newly designed detection electronics in the head provide to very low noise levels. Additionally, the compact folded design of the laser beam path makes the system immune to drift.

Double-beam or multi-beam configurations, combined solutions for coarse and extra precise sample positioning give the user flexibility. Several beam steering options including the newly designed pivot-point piezo-driven mirrors and fast acousto-optic deflectors (AODs) perfectly match requirements of any application.

In addition to extensive sample positioning control including a customized closed-loop piezo sample stage option, the traps can be steered individually in 3D through the sample. Moreover, the laser power can be controlled for both traps independently. This freedom is required to allow a wide range of experimental assays and geometries.

The two traps are available full time and are generated from a single laser source by polarization splitting. This makes the system ultra-stable against drift.

The new back focal plane interferometry detection unit of the NanoTracker™ 2 is equipped with individual detectors for each trap having separate diodes to lateral (XY) and axial (Z) displacements of the trapped bead. Such a detection approach, in combination with software-controlled dimming filters, allows the use of the full dynamic range of the detectors, achieving the highest possible sensitivity for any selected bead types, laser intensities and trap split ratios.

Important for exact force measurements are precise calibration of the traps, lowest position noise and a flat trap stiffness profile over a large field of view. The new precise and flexible one-button trap calibration procedure is independent from bead size and medium viscosity. The cross-talk between trap signals in the detection is drastically reduced.

Single-molecules & biopolymers

  • Intra-molecular elasticity & protein folding dynamics
  • Motor protein tracking
  • DNA/RNA mechanics
  • Protein-DNA binding
  • Nanopores & 3D polymer network probing

DNA elasticity measurement [1] and ds-DNA stretching between two trapped beads in force-clamping mode [2]

Cell biology applications

  • Membrane organization (e.g., lipid rafts)
  • Trans-membrane processes, trafficking
  • Intracellular forces
  • Receptor-ligand experiments
  • Cell mechanics and cell motility
  • Membrane tether dynamics
  • Micro-rheology of cells and gels

The images show the JPK PetriDishHeater™ for live-cell experiments, CHO cell with a membrane pulled by an optically trapped protein-coated bead [1] and corresponding force vs. distance plot [2]

Cell-particle interaction and infection studies

  • Tracking of pathogen-host interaction and escape forces
  • Bacterial and virus adhesion forces
  • Local gene or drug delivery
  • Entrance mechanism studies
  • Nanotoxicity & endocytosis studies

Bright field image of a MDCK cell approaching and retracting a carboxyl-coated polystyrene bead [1] and corresponding force vs. distance plot [2]. Single-virus force measurement: Influenza virus-coated beads where moved toward a cell until touching, and subsequently retracted [3] (Adopted from C. Sieben et al., PNAS 2012, vol. 109 pp. 13626-31.).

Advanced measurements

  • Complex optical trap geometries
  • Optical guiding & artificial crystal building
  • Local field enhancement & Raman/SERS applications
  • Brownian motion tracking, Photonic Force Microscopy (PFM)
  • Colloidal and polymer meshworks force probing
  • Video particle tracking and optical spectroscopy

Bright field image of four polystyrene 2 μm beads held by multiplexed traps [1] and force measurements obtained during viscous drag experiment, where a piezo was oscillating with constant speed of 100 μm/s [2]. Thermal motion plot of a 1 µm silica particle in the trap volume [3].

Key features

Setup Image Nano Tracker 2
  • 3D force measurements with femto-Newton sensitivity and sub-nm precision
  • Highest stability and lowest noise level for the most accurate measurements
  • Simultaneous fluorescence imaging
  • Powerful, flexible control and data analysis software
  • Class 1 laser certified
  • Flexible, modular design for applications ranging from single-molecules to living cells