Guided neuronal growth using optical line traps

SUPA, School of Physics & Astronomy, University of St Andrews, St Andrews, KY16 9SS, Scotland, UK.
Optics Express (Impact Factor: 3.49). 08/2008; 16(14):10507-17. DOI: 10.1364/OE.16.010507
Source: PubMed


Optically guided neuron growth is a relatively new field where the exact mechanisms that initiate growth are not well understood. Both Gaussian light beams and optical line traps have been purported to initiate neuronal growth. Here we present a detailed study using optical line traps with symmetric and asymmetric intensity profiles which have been previously reported to bias the direction of neuronal growth. In contrast to these previous studies, we show similar levels of growth regardless of the direction of the intensity variation along the line trap. Furthermore, our experimental observations confirm previous suggestions that the filopodia produced from neuronal growth cones can be affected by laser light. We experimentally observe alignment of filopodia with the laser field and present a theoretical model describing the optical torques experienced by filopodia to explain this effect.

Download full-text


Available from: Frank J Gunn-Moore,
23 Reads
  • Source
    • "Clearly, optical neuronal guidance has been demonstrated across a broad range of laser wavelengths, spot sizes, spot intensities , beam shapes and beam modulations. Moreover, for the low laser-power in the optical guidance experiments, the magnitude of optical forces is minute (Ehrlicher et al., 2002), and although it has been hypothesized that the very low optical gradient forces played a role in steering the neuronal growth cones with optical line traps (Mohanty et al., 2005), this has later been disproven (Carnegie et al., 2008). This makes an explanation of the underlying mechanism based on optical gradient forces unlikely. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Recently, it has been shown that it is possible to control the growth direction of neuronal growth cones by stimulation with weak laser light; an effect dubbed optical neuronal guidance. The effect exists for a broad range of laser wavelengths, spot sizes, spot intensities, optical intensity profiles and beam modulations, but it is unknown which biophysical mechanisms govern it. Based on thermodynamic modeling and simulation using published experimental parameters as input, we argue that the guidance is linked to heating. Until now, temperature effects due to laser-induced heating of the guided neuron have been neglected in the optical neuronal guidance literature. The results of our finite-element-method simulations show the relevance of the temperature field in optical guidance experiments and are consistent with published experimental results and modeling in the field of optical traps. Furthermore, we propose two experiments designed to test this hypotheses experimentally. For one of these experiments, we have designed a microfluidic platform, to be made using standard microfabrication techniques, for incubation of neurons in temperature gradients on micrometer lengthscales.
    Journal of Neuroscience Methods 02/2012; 209(1):168-77. DOI:10.1016/j.jneumeth.2012.02.006 · 2.05 Impact Factor
  • Source
    • "Neurons functionally reshape their interconnectivity not only in response to incoming activity from other cells, but also to external stimuli and changes of environmental conditions (Muotri and Gage 2006). Thus, studying cell physiology, cell motility and interconnectivity by interacting with cells or their organelles (Carnegie et al. 2008; Kress et al. 2009; Mejean et al. 2009) and controlling the intercellular organization and environment (Macdonald et al. 2002; Steubing et al. 1991) may lead to a better understanding of cell growth and differentiation during the formation of a specific tissue architecture . For instance, during differentiation, cell processes such as lamellipodia and filopodia explore the extracellular matrix by random motion (Goodman 1996) biased by chemical and physical constraints (Allioux-Guerin et al. 2008), which Address correspondence to F. Difato, Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, via Morego 30, 16163, Genoa, Italy. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We present an optical system that combines IR (1064 nm) holographic optical tweezers with a sub-nanosecond-pulsed UV (355 nm) laser microdissector for the optical manipulation of single neurons and entire networks both on transparent and non-transparent substrates in vitro. The phase-modulated laser beam can illuminate the sample concurrently or independently from above or below assuring compatibility with different types of microelectrode array and patch-clamp electrophysiology. By combining electrophysiological and optical tools, neural activity in response to localized stimuli or injury can be studied and quantified at sub-cellular, cellular, and network level.
    International Journal of Optomechatronics 07/2011; 5(3-3):191-216. DOI:10.1080/15599612.2011.604246 · 0.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We have successfully applied an optical tweezer for mapping the velocity profile in microfluidic channels. The velocity profiles for a straight and a u-shaped microfluidic channels were determined by direct measurment of the Stokes force. ©2009 Optical Society of America OCIS codes: (350.4855) Optical tweezers or optical manipulation; (280.4788) Optical sensing and sensors; Ever since optical trapping was discovered and the first experimental observation was reported in 1970's [1, 2], the ability to manipulate microscopic objectives has promised great potential. However, it was not until after 1986 when A. Ashkin and S. Chu demonstrated the first optical tweezer [3] that optical trapping successfully found its major application in biology [4]. Since then, a substantial number of scientific discoveries have been reported using this technology [5-7]. Nevertheless researchers are continually looking for wider applications of this powerful tool in other branches of sciences and technologies. Microfluidics deals with fluids that flow at micrometer scale and couples with numerous fields such as physics, life sciences, chemistry and medicine by miniaturized fluidic devices and superior performance over conventional macroscopic systems [8]. In order to understand the dynamics of the fluid in a microfluidic system, which differ from those in macroscopic environment, great effort has been put into mapping of velocity profiles inside devices however most methods, such as scalar image velocimetry [9] and laser doppler velocimetry [10] are not really compatible with microfluidic environment. The most commonly used method of fluidic velocity characterization in a microfluidic device is microparticle image velocimetry [11], however there is the potential that the dense suspension of tracer particles will have a negative influence on the fluid to be detected. It is therefore desired that a method tailored specifically for microfluidic systems be developed. Due to the non-invasive nature of optical tweezers, its high sensitivity as well as the ability to achieve localized sensing, the marriage of optical tweezers and microfluidics seems to be a perfect match.
Show more