Intracellular nanomanipulation by a photonic-force microscope with real-time acquisition of a 3D stiffness matrix

A traditional photonic-force microscope (PFM) results in huge sets of data, which requires tedious numerical analysis. In this paper, we propose instead an analog signal processor to attain real-time capabilities while retaining the richness of the traditional PFM data. Our system is devoted to intracellular measurements and is fully interactive through the use of a haptic joystick. Using our specialized analog hardware along with a dedicated algorithm, we can extract the full 3D stiffness matrix of the optical trap in real time, including the off-diagonal cross-terms. Our system is also capable of simultaneously recording data for subsequent offline analysis. This allows us to check that a good correlation exists between the classical analysis of stiffness and our real-time measurements. We monitor the PFM beads using an optical microscope. The force-feedback mechanism of the haptic joystick helps us in interactively guiding the bead inside living cells and collecting information from its (possibly anisotropic) environment. The instantaneous stiffness measurements are also displayed in real time on a graphical user interface. The whole system has been built and is operational; here we present early results that confirm the consistency of the real-time measurements with offline computations.

[1]  Jonathon Howard,et al.  Surface forces and drag coefficients of microspheres near a plane surface measured with optical tweezers. , 2007, Langmuir : the ACS journal of surfaces and colloids.

[2]  Ernst H. K. Stelzer,et al.  Three-dimensional thermal noise imaging , 2001 .

[3]  SONG ZHANG,et al.  Diffusion Tensor MRI Visualization , 2005, The Visualization Handbook.

[4]  G. Uhlenbeck,et al.  On the Theory of the Brownian Motion II , 1945 .

[5]  E. Stelzer,et al.  Trapping and tracking a local probe with a photonic force microscope , 2004 .

[6]  Helmut Grubmüller,et al.  Mechanical properties of single motor molecules studied by three-dimensional thermal force probing in optical tweezers. , 2004, Chemphyschem : a European journal of chemical physics and physical chemistry.

[7]  Christoph F. Schmidt,et al.  Power spectrum analysis for optical tweezers. II: Laser wavelength dependence of parasitic filtering, and how to achieve high bandwidth , 2006 .

[8]  Miriam W. Allersma,et al.  Two-dimensional tracking of ncd motility by back focal plane interferometry. , 1998, Biophysical journal.

[9]  C. Schmidt,et al.  Interference model for back-focal-plane displacement detection in optical tweezers. , 1998, Optics letters.

[10]  Henrik Flyvbjerg,et al.  In situ viscometry by optical trapping interferometry , 2008 .

[11]  E. Stelzer,et al.  Three-dimensional position detection of optically trapped dielectric particles , 2002 .

[12]  Thomas Franosch,et al.  Anisotropic memory effects in confined colloidal diffusion. , 2008, Physical review letters.

[13]  László Forró,et al.  Motion of a colloidal particle in an optical trap. , 2007, Physical review. E, Statistical, nonlinear, and soft matter physics.

[14]  I. Tolic-Nørrelykke,et al.  Anomalous diffusion in living yeast cells. , 2004, Physical review letters.

[15]  Ernst H. K. Stelzer,et al.  Local viscosity probed by photonic force microscopy , 1998 .