Analysis of laser-induced heating in optical neuronal guidance

Abstract

a b s t r a c tRecently, 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.

Effects of laser-exposed gold nanorods on biochemical pathways of neuronal cells

“…It is known that calcium ions are an integral part of common signalling pathways and have been extensively studied for their role in cell responses such as mitosis, apoptosis, muscle contraction and neurite extension. 20,21 It is hypothesised that the recorded cytoplasmic Ca 2+ elevations caused by laser -exposed NRs might be correlated with the neurite outgrowth described in Ref. 10.…”

Gold Nanorod-assisted Optical Stimulation of Neuronal Cells

“…Calcium ions play an important role in different cellular activities, such as mitosis, muscle contraction and neurite extension 25,26 . In response to a stimulus, Ca 2+ increases, oscillates and decreases, leading to the activation, modulation or termination of a specific cell function.…”

“…Different groups have also demonstrated that small temperature gradients over the physiological temperature range can be used to induce other responses, such as neuronal growth cone guiding 25 or depolarizing currents in human embryonic kidney cells 35 . Yong and coworkers recorded a significant increase in electrical signal activity in primary auditory neurons cultured with silica-coated Au NRs after laser irradiation of the NRs at the LSPR.…”

Damage criteria for cerebral cortex cells subjected to hyperthermia

“…It relies on local temperature elevations caused by infrared light to functionally stimulate excitable cells to depolarise. Several papers have been published showing that infrared light can be used as a stimulus to excite neurons, cardiac myocytes as well as to act as a cue for guiding cell growth [12][13][14][15]. In addition to neural activation, neural inhibition has also been reported [16][17][18][19].…”