研究目的
To develop a general bioconjugation strategy for tethering gold nanoparticles (AuNPs) to the plasma membrane of electrically-excitable cells using cholesterol functionalization, enabling light-induced action potential generation without targeting specific membrane proteins.
研究成果
AuNP-PEG-Chol conjugates effectively confer light-induced action potential generation in neurons through optocapacitive mechanisms, demonstrating a generalizable strategy for neural photosensitization without protein-specific targeting. This approach offers advantages for exploring tissue suitability and potential therapeutic applications, with future work needed on tunability and combined drug delivery.
研究不足
The study is limited to in vitro experiments with DRG neurons and HEK cells; in vivo applicability is not addressed. Heterogeneity in plasma membrane labeling may affect consistency of photoresponsiveness. The approach relies on low nM concentrations, but optimal dosing and long-term effects are not fully explored. The mechanism assumes close tethering for efficient heat transfer, which may vary with cell type or membrane composition.
1:Experimental Design and Method Selection:
The study involved synthesizing 20 nm spherical AuNPs functionalized with PEGylated cholesterol (AuNP-PEG-Chol) to test their ability to tether to neuronal plasma membranes and induce action potentials via plasmonic heating upon laser excitation. Theoretical models for heat conduction and optocapacitive mechanisms were employed.
2:Sample Selection and Data Sources:
Dorsal root ganglion (DRG) neurons from newborn rats and HEK 293T/17 cells were used. Neurons were isolated, cultured, and labeled with AuNP conjugates. Data were collected through electrophysiological recordings under current-clamp conditions.
3:List of Experimental Equipment and Materials:
Equipment included a Zeiss IM 35 microscope, Axopatch 200B amplifier, Sutter Instruments P-2000 CO2 laser micropipette puller, 532 nm DPSS laser, acousto-optic modulator, Nikon A1RSi confocal microscope, Shimadzu UV-1800 spectrophotometer, JEOL 2200-FX TEM, ZetaSizer NanoSeries for DLS, and various chemicals like HAuCl4, PEG derivatives, and cell culture reagents from Sigma and Life Technologies.
4:Experimental Procedures and Operational Workflow:
AuNPs were synthesized and functionalized with TA-PEG-COOH and PEG-Chol via carbodiimide chemistry. Cells were incubated with AuNP conjugates, washed, and subjected to laser pulses of varying durations and powers while recording membrane voltages. Intracellular delivery was achieved by including AuNPs in the patch pipette solution.
5:Data Analysis Methods:
Data were analyzed using customized software for electrophysiology, with statistical analysis of resting potentials, depolarization amplitudes, and threshold energies. Power law relationships were fitted to the data, and cytotoxicity was assessed using proliferation and viability assays.
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Microscope
Zeiss IM 35
Carl Zeiss Microscopy
Visualization of cells during electrophysiological recordings.
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Spectrophotometer
UV-1800
Shimadzu
UV-Vis spectroscopy for AuNP characterization.
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Transmission Electron Microscope
JEOL 2200-FX
JEOL
Structural characterization and elemental analysis of AuNPs.
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Dynamic Light Scattering Instrument
ZetaSizer NanoSeries
Malvern Instruments
Measurement of hydrodynamic size and zeta potential of AuNPs.
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Gold Nanoparticle
20 nm spherical
Used as photoactivatable material for plasmonic heating to induce action potentials in neurons.
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Amplifier
Axopatch 200B
Molecular Devices
Current-clamp membrane voltage recording.
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Laser
532 nm DPSS laser
UltraLasers
Photoexcitation of AuNPs with 532 nm light pulses.
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Acousto-optic Modulator
NEOS Technologies, Gooch & Housego
Control of laser pulse presentation.
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Confocal Microscope
Nikon A1RSi
Nikon
Imaging of cellular labeling with fluorescent conjugates.
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Micropipette Puller
P-2000 CO2 laser
Sutter Instruments
Pulling patch pipettes for electrophysiology.
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