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Updated: Sep 28, 2025
Optical Trapping of Plasmonic Nanoparticles for In Situ Surface-Enhanced Raman Spectroscopy Characterizations
Published on: June 23, 2022
Detection of Glutamate Encapsulated in Liposomes by Optical Trapping Raman Spectroscopy
Kyoko Masui1,2, Yasunori Nawa1,3, Shunsuke Tokumitsu1,3
1Advanced Photonics and Biosensing Open Innovation Laboratory, National Institute of Advanced Industrial Science and Technology, 2-1, Yamadaoka, Suita, Osaka 5650871, Japan.
Researchers developed an optical trapping Raman spectroscopy system to measure glutamate concentration in single synaptic vesicles. This technique allows for quantitative analysis of neurotransmitter levels within these tiny structures, crucial for understanding brain function and disease.
Area of Science:
- Neuroscience
- Biophysics
- Spectroscopy
Background:
- Neuronal communication relies on neurotransmitters like glutamate released from synaptic vesicles.
- Quantifying glutamate concentration in single vesicles is vital for understanding brain function and neurological disorders.
- The small size of synaptic vesicles (∼40 nm) presents challenges for direct measurement.
Purpose of the Study:
- To develop a method for quantitatively measuring the concentration of glutamate within single synaptic vesicles.
- To assess the feasibility of using optical trapping Raman spectroscopy for this purpose.
Main Methods:
- Development of an optical trapping Raman spectroscopic system.
- Utilizing artificial liposomes encapsulating glutamate to mimic synaptic vesicles.
- Employing a 575 nm laser for simultaneous optical trapping and Raman spectroscopy.
- Analyzing Raman spectra of trapped liposomes to quantify encapsulated glutamate.
Main Results:
- Successfully detected spontaneous Raman scattered light from glutamate within trapped liposomes.
- Established a calibration curve using glutamate solutions of known concentrations.
- Demonstrated the ability to estimate the number of glutamate molecules in trapped liposomes.
Conclusions:
- The developed optical trapping Raman spectroscopy system enables quantitative measurement of glutamate concentration in single vesicles.
- This technique offers a novel approach for *in situ* analysis of neurotransmitter content in synaptic vesicles.
- The findings contribute to a better understanding of synaptic transmission and glutamate-related neurological conditions.
