Dataset Information

Theoretical Study on Gold-Nanorod-Enhanced Near-Infrared Neural Stimulation.

ABSTRACT: Over the past decade, optical methods have emerged for modulating brain functions as an alternative to electrical stimulation. Among various optical techniques, infrared neural stimulation has been effective via a thermal mechanism enabling focused and noninvasive stimulation without any genetic manipulation, but it results in bulk heating of neural tissue. Recently, it has been shown that neural cells can be activated more efficiently by pulsed near-infrared (NIR) light delivered to gold nanorods (GNRs) near the neural cells. Despite its potential, however, the biophysical mechanism underlying this GNR-enhanced NIR stimulation has not been clearly explained yet. Here, we propose an integrative and quantitative model to elucidate the mechanism by modeling heat generated from interaction between NIR light and GNRs, the temperature-dependent ion channels (transient receptor potential vanilloid 1; TRPV1) in the neuronal membrane, and a heat-induced capacitive current through the membrane. Our results show that NIR pulses induce abrupt temperature elevation near the neuronal membrane and lead to both the TRPV1-channel and capacitive currents. Both current sources synergistically increase the membrane potential and elicit an action potential, and which mechanism is dominant depends on conditions such as the laser pulse duration and TRPV1 channel density. Although the TRPV1 mechanism dominates in most cases we tested, the capacitive current makes a larger contribution when a very short laser pulse is illuminated on neural cells with relatively low TRPV1 channel densities.

SUBMITTER: Eom K

PROVIDER: S-EPMC6372194 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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Theoretical Study on Gold-Nanorod-Enhanced Near-Infrared Neural Stimulation.

Eom Kyungsik K Byun Kyung Min KM Jun Sang Beom SB Kim Sung June SJ Lee Jonghwan J

Biophysical journal 20180913 8

Over the past decade, optical methods have emerged for modulating brain functions as an alternative to electrical stimulation. Among various optical techniques, infrared neural stimulation has been effective via a thermal mechanism enabling focused and noninvasive stimulation without any genetic manipulation, but it results in bulk heating of neural tissue. Recently, it has been shown that neural cells can be activated more efficiently by pulsed near-infrared (NIR) light delivered to gold nanoro ...[more]

PMID: 30266321

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Project description:As biospectroscopy techniques continue to be developed for screening or diagnosis within a point-of-care setting, an important development for this field will be high-throughput optimization. For many of these techniques, it is therefore necessary to adapt and develop parameters to generate a robust yet simple approach delivering high-quality spectra from biological samples. Specifically, this is important for surface-enhanced Raman spectroscopy (SERS) wherein there are multiple variables that can be optimised to achieve an enhancement of the Raman signal from a sample. One hypothesis is that "large" diameter (>100 nm) gold nanoparticles provide a greater enhancement at near-infrared (NIR) and infrared (IR) wavelengths than those <100 nm in diameter. Herein, we examine this notion using examples in which SERS spectra were acquired from MCF-7 breast cancer cells incubated with 150 nm gold nanoparticles. It was found that 150 nm gold nanoparticles are an excellent material for NIR/IR SERS. Larger gold nanoparticles may better satisfy the theoretical restraints for SERS enhancement at NIR/IR wavelengths compared to smaller nanoparticles. Also, larger nanoparticles or their aggregates are more readily observed via optical microscopy (and especially electron microscopy) compared to smaller ones. This allows rapid and straightforward identification of target areas containing a high concentration of nanoparticles and facilitating SERS spectral acquisition. To some extent, these observations appear to extend to biofluids such as blood plasma or (especially) serum; SERS spectra of such biological samples often exhibit a low signal-to-noise ratio in the absence of nanoparticles. With protein-rich biofluids such as serum, a dramatic SERS effect can be observed; although this might facilitate improved spectral biomarker identification in the future, it may not always improve classification between control vs. cancer. Thus, use of "large" gold nanoparticles are a good starting point in order to derive informative NIR/IR SERS analysis of biological samples.

Dataset Information

Theoretical Study on Gold-Nanorod-Enhanced Near-Infrared Neural Stimulation.

Publications

Theoretical Study on Gold-Nanorod-Enhanced Near-Infrared Neural Stimulation.

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