SEROA studies were focused on interactions between a chiral analyte and metal
nanoparticles [30]. Recently, Blanch et al. [58] showed a new chirality induction
mechanism; i.e., the SERROA signal was collected for an achiral benzotriazole dye
reporter placed in the vicinity of achiral silver nanoparticles and induced by a chiral
analyte.
6.2 Application of Raman Spectroscopy to In Vitro
Endothelial Cell Cultures
From small molecules, through simple systems to highly sophisticated ones such as
single cells or tissues, Raman spectroscopy enables deciphering the structural and
chemical composition. A strong potential of this technique is in providing information from various samples important in biology and medicine noninvasively and
in a label-free manner. Identifying, interpreting, and understanding of the studied
samples are possible based on basic knowledge about the structure of compounds
and analysis of characteristic bands in their Raman spectra. For example, investigation of individual proteins [59] can be used to determine and define alterations in
the secondary structures of proteins in tissues [60] and spectroscopic analysis of
plant metabolites enables discrimination of different plant species and even
chemotypes [61]. Some biologically active compounds, for example hemoproteins
and lipids, exhibit very intense Raman signals due to resonance enhancement
(hemoproteins if irradiated with the wavelength in the suitable range) or the
molecular structure (the presence of long, nonpolar hydrocarbon chains in lipids).
Therefore, lipids are ideal specimens for Raman studies due to the large Raman
scattering cross section [62]. In case of biomedical applications, their analysis is
particularly important because changes in the lipid concentration and composition
are associated with many diseases, i.e., atherosclerosis or diabetes. On the whole,
the knowledge of the most characteristic marker features for groups of different
biocompounds facilitates analysis of complex Raman spectra of cells and tissues.
There are many analytical techniques for in vitro imaging. Historically, the first
attempts to visualize cells were based on fixed preparations initially using optical
microscopy and later electron microscopy. The latter technique enables imaging of
intracellular structures and organelles with a very high resolving power, however,
provide only morphological information. Similarly, development of microscopic
techniques in a bright field, based on phase contrast and differential interference
field, made possible observation of samples without fixation and even staining, and
imaging of living cells. The use of these techniques enables real-time imaging, but
they do not provide information about the chemical composition of cells. Modern
techniques of fluorescence microscopy yield highly resolved images, nevertheless,
only a limited number of components can be studied in one experiment, and
application of these methods requires long-lasting and laborious preparations of
samples. These problems do not concern Raman microscopy. The information
170
K. Czamara et al.
nanoparticles [30]. Recently, Blanch et al. [58] showed a new chirality induction
mechanism; i.e., the SERROA signal was collected for an achiral benzotriazole dye
reporter placed in the vicinity of achiral silver nanoparticles and induced by a chiral
analyte.
6.2 Application of Raman Spectroscopy to In Vitro
Endothelial Cell Cultures
From small molecules, through simple systems to highly sophisticated ones such as
single cells or tissues, Raman spectroscopy enables deciphering the structural and
chemical composition. A strong potential of this technique is in providing information from various samples important in biology and medicine noninvasively and
in a label-free manner. Identifying, interpreting, and understanding of the studied
samples are possible based on basic knowledge about the structure of compounds
and analysis of characteristic bands in their Raman spectra. For example, investigation of individual proteins [59] can be used to determine and define alterations in
the secondary structures of proteins in tissues [60] and spectroscopic analysis of
plant metabolites enables discrimination of different plant species and even
chemotypes [61]. Some biologically active compounds, for example hemoproteins
and lipids, exhibit very intense Raman signals due to resonance enhancement
(hemoproteins if irradiated with the wavelength in the suitable range) or the
molecular structure (the presence of long, nonpolar hydrocarbon chains in lipids).
Therefore, lipids are ideal specimens for Raman studies due to the large Raman
scattering cross section [62]. In case of biomedical applications, their analysis is
particularly important because changes in the lipid concentration and composition
are associated with many diseases, i.e., atherosclerosis or diabetes. On the whole,
the knowledge of the most characteristic marker features for groups of different
biocompounds facilitates analysis of complex Raman spectra of cells and tissues.
There are many analytical techniques for in vitro imaging. Historically, the first
attempts to visualize cells were based on fixed preparations initially using optical
microscopy and later electron microscopy. The latter technique enables imaging of
intracellular structures and organelles with a very high resolving power, however,
provide only morphological information. Similarly, development of microscopic
techniques in a bright field, based on phase contrast and differential interference
field, made possible observation of samples without fixation and even staining, and
imaging of living cells. The use of these techniques enables real-time imaging, but
they do not provide information about the chemical composition of cells. Modern
techniques of fluorescence microscopy yield highly resolved images, nevertheless,
only a limited number of components can be studied in one experiment, and
application of these methods requires long-lasting and laborious preparations of
samples. These problems do not concern Raman microscopy. The information
170
K. Czamara et al.