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SERS mapping in Langmuir-Blodgett films and single-molecule detection
Pedro H B Aoki1, Eduardo G E Carreon, Diogo Volpati
1Faculdade de Ciências e Tecnologia, UNESP Universidade Estadual Paulista, Presidente Prudente/SP, 19060-900, Brazil.
Applied Spectroscopy
|May 7, 2013
Summary
Single-molecule detection (SMD) using surface-enhanced Raman scattering (SERRS) was achieved by doping a phospholipid monolayer with methylene blue (MB). This electrostatic approach enabled observation of rare, single-molecule events for advanced spectroscopic analysis.
Area of Science:
- Plasmonics
- Spectroscopy
- Nanotechnology
Background:
- Plasmon-enhanced spectroscopic techniques, like surface-enhanced Raman scattering (SERRS), enable single-molecule detection (SMD).
- SMD is crucial for advancements in bio-imaging and single-cell manipulation.
- SERRS provides high sensitivity and molecular-fingerprint information at the single-molecule level.
Purpose of the Study:
- To report a single-molecule detection study using an electrostatic approach.
- To demonstrate the observation of single-molecule events in a doped Langmuir film.
- To apply advanced fitting techniques for real-time processing of single-molecule spectra.
Main Methods:
- Utilized an electrostatic approach to dope a Langmuir film of a phospholipid with cationic methylene blue (MB).
- Created a homogeneous, two-dimensional distribution of MB dyes within the monolayer.
- Employed Langmuir-Blodgett (LB) film coating on silver (Ag) nanostructures.
- Performed micro-Raman mapping and advanced fitting techniques for data analysis.
Main Results:
- Achieved single-molecule detection (SMD) by observing rare events where single molecules were in plasmonic hot-spots.
- Identified single-molecule spectra by direct matching with reference spectra for MB.
- Successfully extracted MB single-molecule spectra using real-time processing via advanced fitting techniques.
Conclusions:
- The electrostatic doping approach provides a viable method for achieving single-molecule detection (SMD) using SERRS.
- Homogeneous dye distribution in LB films on plasmonic substrates facilitates SMD.
- Advanced fitting techniques are effective for real-time analysis and extraction of single-molecule SERRS spectra.
