Thermogenetic neurostimulation with single-cell resolution
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-05-22 |
| Journal | Nature Communications |
| Authors | Yulia G. Ermakova, A. Đ. Lanin, Ilya V. Fedotov, Matvey Roshchin, Ilya V. Kelmanson |
| Institutions | Institute of Bioorganic Chemistry, Institute of Higher Nervous Activity and Neurophysiology |
| Citations | 82 |
| Analysis | Full AI Review Included |
Technical Documentation & Sales Prospectus: Diamond for High-Resolution Thermogenetics
Section titled âTechnical Documentation & Sales Prospectus: Diamond for High-Resolution ThermogeneticsâSource Paper: Ermakova et al., âThermogenetic neurostimulation with single-cell resolutionâ (Nature Communications, 2017)
Executive Summary
Section titled âExecutive SummaryâThe research details a breakthrough methodology for thermogenetic neurostimulation, achieving single-cell spatial resolution and high temporal precision by integrating Nitrogen-Vacancy (NV) diamond quantum sensors with IR laser photonics. This framework sets a new standard for non-invasive manipulation of neural circuits.
- Core Achievement: Demonstrated robust and reproducible activation of snake TRPA1 channels in mouse and zebrafish neurons using localized IR laser heating.
- Enabling Technology: Integration of a fibre-optic probe with a 300 ”m diameter NV diamond crystal for highly localized, in situ thermometry.
- Precision and Resolution: Thermometry achieved single-cell resolution with 0.1 °C sensitivity, crucial for applying âexceptionally mild heatingâ to prevent cell damage.
- IR Photonics Advantage: Use of 1,440 nm (optimal water absorption) and 1,350 nm IR wavelengths provides superior tissue penetration compared to visible light optogenetics.
- Activation Thresholds: Successful activation achieved at exceptionally low temperature thresholds (caTRPA1 ~27.8 °C, eolTRPA1 ~38.5 °C).
- Temporal Control: Ultrafast channel activation rates, enabling phase-locked neuronal responses to pulsed IR trains (e.g., 25 Hz and 50 Hz trains).
- Material Focus: High-quality, precision-cut Single Crystal Diamond (SCD) is foundational for generating reliable NV quantum sensors required for this platform.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Sensor Diameter | 300 | ”m | NV diamond crystal attached to fiber tip for thermometry. |
| NV Thermometry Sensitivity | 0.1 | °C | High-resolution temperature measurement. |
| IR Wavelength (Optimal Water Absorp.) | 1,440 | nm | Used for localized heating of mammalian cells. |
| IR Wavelength (Zebrafish Study) | 1,350 | nm | Chosen for stable temperature profile within the aquatic environment. |
| IR Laser Pulse Duration | < 60, 10, 30, 50 | fs, ms | Ultrashort pulses for heating; millisecond pulses for AP induction. |
| Laser Repetition Rate (Quasi-CW) | 78 | MHz | Standard OPO output, modulated for pulse trains. |
| Heating Rate per Unit Power (λ=1,440 nm) | 0.25 ± 0.01 | K mW-1 | Measured heating efficiency in the sample. |
| caTRPA1 Activation Temperature (TON) | 27.8 ± 0.6 | °C | Threshold for activation in HEK293 cells (low threshold). |
| eolTRPA1 Activation Temperature (TON) | 38.5 ± 0.7 | °C | Threshold closer to mammalian physiological temperature. |
| Maximum Neuronal Temperature Tested | 40 | °C | Upper limit for mild, non-toxic heating. |
| Ca2+ Decay Time (Exponential Fit) | 3.5 ± 0.1 | s | Observed decay dynamics in GCaMP6s fluorescence. |
| Single AP Induction Energy (1,342 nm, 10 ms) | 1.0 - 1.7 | mJ | Energy range for single action potential (AP) in cultured neurons. |
Key Methodologies
Section titled âKey MethodologiesâThe experimental design required high-precision integration of optical, microwave, and diamond material components to achieve accurate, localized heating and thermometry.
- Diamond Quantum Sensing Probe Construction: A 300 ”m diameter Nitrogen-Vacancy (NV) diamond crystal was precision-attached to the tip of an optical fiber (fiber-optic probe).
- Thermometry Method: Temperature measurements were performed in situ with single-cell resolution using Optically Detected Magnetic Resonance (ODMR) of the NV centers, requiring precise microwave delivery.
- IR Laser Source: A femtosecond Optical Parametric Oscillator (OPO), pumped by a Ti:Sapphire laser, was used as the tunable, quasi-continuous-wave (quasi-cw) IR source.
- Wavelength Tuning: The OPO output was tuned to 1,440 nm (local maximum of water absorption) for maximal local heating efficiency, or 1,350 nm for stable deep-tissue profiles in zebrafish larvae.
- Heating Control: Laser irradiation intensity was finely adjusted to achieve mild, sub-threshold heating, followed by rapid, precisely controlled stepwise increases (0.5-1 °C min-1) to cross the TRPA1 activation thresholds.
- Neuronal Response Assessment: Activation was characterized by Ca2+ imaging (using R-GECO1.1 and GCaMP6s indicators) and direct electrophysiological patch-clamp recording of action potentials (APs).
- Pulsed Stimulation: IR laser trains (e.g., 10 ms pulses at 25 Hz or 50 Hz) were used to demonstrate phase-locked, rapid neuronal firing, proving the utility of IR photonics for temporal control.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research validates the critical role of highly customized, high-quality diamond materials in advancing next-generation neuroscience tools. 6CCVD, as a specialist in MPCVD diamond engineering, is uniquely positioned to supply the materials required to replicate, scale, and extend this quantum thermogenetics platform.
Applicable Materials for Quantum Thermogenetics
Section titled âApplicable Materials for Quantum ThermogeneticsâReplication of the NV diamond sensor requires high-purity, low-defect, Single Crystal Diamond (SCD), typically grown via MPCVD.
| 6CCVD Material Specification | Relevance to Application | Features & Benefits |
|---|---|---|
| Optical Grade SCD (0.1 ”m to 500 ”m thickness) | Source Material for NV Centers | SCD provides the ultra-low nitrogen/defect background necessary for stable, high-density NV center creation (via post-processing implantation or in situ doping), ensuring maximal coherence time and temperature sensitivity (0.1 °C). |
| Precision PCD (Polycrystalline Diamond) Substrates | Heat Sink/Integration Platform | For larger scale, multi-fiber probes or planar sensor arrays, PCD offers high thermal conductivity (ideal for localized heat dissipation) and superior mechanical stability. |
| Custom Boron-Doped (BDD) Diamond | Electrophysiology/Interface | If integrated electrodes or electrochemical sensing were needed alongside thermometry, 6CCVD provides BDD diamond films capable of functioning as inert, high-performance electrode materials. |
Customization Potential for Probe Development
Section titled âCustomization Potential for Probe DevelopmentâThe core challenge in integrating the NV sensor is achieving the specific small dimensions and high surface quality required for robust fiber coupling and localized measurement (300 ”m diameter). 6CCVDâs specialized engineering capabilities address these needs directly.
- Precision Shaping and Cutting: The paper utilized a 300 ”m diameter diamond crystal. 6CCVD offers high-resolution laser cutting and shaping services, capable of fabricating SCD plates or wafers into custom dimensions required for precise fiber-optic probe integration, including diameters < 300 ”m or complex geometries.
- Advanced Polishing (Ra < 1 nm): The NV sensor requires excellent optical interfacing (for IR laser delivery and fluorescence collection). 6CCVD guarantees Ra < 1 nm surface roughness for SCD, ensuring optimal optical coupling efficiency and minimal scattering losses critical for ODMR thermometry.
- Custom Metalization: Should the researchers require precise bonding or electronic interfacing layers for fiber attachment or microwave delivery (e.g., Ti/Pt/Au for bonding the diamond tip), 6CCVD maintains in-house metalization capabilities (Au, Pt, Pd, Ti, W, Cu).
- Thickness Control: We provide SCD materials from ultra-thin 0.1 ”m films up to 500 ”m substrates, allowing researchers to optimize the sensor volume for maximum NV density while minimizing thermal mass.
Engineering Support & Logistics
Section titled âEngineering Support & Logisticsâ6CCVD recognizes that integrating quantum sensors into biological systems is complex. Our in-house PhD team can assist with material selection for similar IR Thermogenetic and Quantum Sensing projects, ensuring diamond specifications align precisely with NV creation protocol and optical system requirements (e.g., choosing the optimal SCD grade for specific irradiation techniques). We provide reliable Global Shipping (DDU default, DDP available) to facilitate the rapid deployment of custom diamond components to research facilities worldwide.
Call to Action: For custom specifications or material consultation regarding high-purity SCD for NV quantum sensing and neurostimulation applications, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract Thermogenetics is a promising innovative neurostimulation technique, which enables robust activation of neurons using thermosensitive transient receptor potential (TRP) cation channels. Broader application of this approach in neuroscience is, however, hindered by a limited variety of suitable ion channels, and by low spatial and temporal resolution of neuronal activation when TRP channels are activated by ambient temperature variations or chemical agonists. Here, we demonstrate rapid, robust and reproducible repeated activation of snake TRPA1 channels heterologously expressed in non-neuronal cells, mouse neurons and zebrafish neurons in vivo by infrared (IR) laser radiation. A fibre-optic probe that integrates a nitrogenâvacancy (NV) diamond quantum sensor with optical and microwave waveguide delivery enables thermometry with single-cell resolution, allowing neurons to be activated by exceptionally mild heating, thus preventing the damaging effects of excessive heat. The neuronal responses to the activation by IR laser radiation are fully characterized using Ca 2+ imaging and electrophysiology, providing, for the first time, a complete framework for a thermogenetic manipulation of individual neurons using IR light.