Biomedical subjects

Nico Dam

Publications and source records attributed to Nico Dam.

2 recordsLinked to original sources

PubMed2006

Monitoring neurotransmitter release using surface-enhanced Raman spectroscopy.

Surface-enhanced Raman spectroscopy (SERS) is a promising tool to monitor neurotransmitter release at the single-cell level: it is a sensitive technique that provides structural information of the released compounds and spatial information about their release sites. In this study we demonstrate that depolarization-evoked catecholamine secretion by rat phaeochromocytoma (PC12) cells can be spatially resolved by SERS using silver colloids. A suitable SERS substrate was created by adding silver colloids to the cell culture medium. Nomarski-DIC microscopy combined with reflection confocal laser scanning microscopy showed that the colloids were primarily present on top of the cell membrane. The SERS spectra were successfully corrected for the contribution of cell constituents. Dopamine and noradrenaline were localized by examining the correlation coefficient between spectra and reference catecholamine spectra. Potential improvements of the temporal resolution of the technique are discussed.

Animals↗

PubMed2004

Quantitative imaging through a spectrograph. 1. Principles and theory.

Laser-based optical diagnostics, such as planar laser-induced fluorescence and, especially, Raman imaging, often require selective spectral filtering. We advocate the use of an imaging spectrograph with a broad entrance slit as a spectral filter for two-dimensional imaging. A spectrograph in this mode of operation produces output that is a convolution of the spatial and spectral information that is present in the incident light. We describe an analytical deconvolution procedure, based on Bayesian statistics, that retrieves the spatial information while it avoids excessive noise blowup. The method permits direct imaging through a spectrograph, even under broadband illumination. We introduce the formalism and discuss the underlying assumptions. The performance of the procedure is demonstrated on an artificial but pathological example. In a companion paper [Appl. Opt. 43, 5682-5690 (2004)] the method is applied to the practical case of fuel equivalence ratio Raman imaging in a combustible methane-air mixture.

Journal Article↗