458
D. P. Singh et al.
tivity, selectivity, and large temporal range, fluorescence spectroscopy has proven
to be a basic tool to reveal the biomolecular dynamics. To study protein structure and dynamics, fluorescence-based methods have the following advantages:
(i) dynamics of a specific group or a segment of a massive macromolecular system
can be observed without interference from the rest of the system; (ii) the timescale
of observable dynamics covers a wide range from femtoseconds to seconds, and
(iii) observations can be made at very low concentrations. In a recent study, Blue
Light Using Flavin (BLUF) domains are attracting interest for use in optogenetic
constructs (Fig. 10c); however, the mechanism of their activation needs to be disclosed. By incorporating a tryptophan analogue, 7-aza-Trp (7AW) into the BLUF
domain, the functional dynamics of the crucial W104 residue can be investigated
during photoactivation of the protein [22].
• Fluorescence imaging modes in live-cell microscopy:
Monitoring the interactions among the cells as they grow is essentially important to understand organismal development. Fluorescence microscopy is the most
widely used tools for high-resolution, noninvasive imaging of live organisms and
organic fluorophores are the most commonly used tags for fluorescence-based
imaging. For labeling specific cellular proteins, fluorescent materials are conjugated to biomolecules that provide binding specificity (Fig. 10d, e) [23, 24].
Bioconjugation approaches vary with the surface properties of the fluorescent
material. The mixed surface self-assembly approach is recommended for conjugating biomolecules to fluorescent material capped with a negatively charged
surface ligand.
• Fluorescence spectral imaging, emission fingerprinting, and tumor detection:
The fluorescent materials are extensively employed in sensing and biomedical
applications. The labelling of multiple antibodies with various fluorophores permits visualization of different targets within a single image of multiple channels
(Fig. 10f). Nowadays, fluorescent materials can also be used such as diagnostic agents for tumor detection through tumor-specific membrane antigens (Fig.
10g), DNA-functionalized probes for real-time identification of disease-relevant
biomolecules, therapeutic efficacy, and molecular probes for simultaneous tracking and monitoring of drug delivery [25, 26]. An approach to measure FRET with
spectral imaging is termed as lambda FRET and has proven to be a highly specific,
sensitive, and robust method for analyzing resonance energy transfer in live cells.
The lambda FRET algorithm relies on imaging of a FRET specimen at multiple
emission wavelengths, followed by separation of the FRET spectrum into its donor
and acceptor components to obtain a pixel-based calculation of FRET efficiency.
In the emission fingerprinting application [27], each fluorophore or an absorbing
dye, regardless of the degree of spectral overlap with other probes, has a unique
spectral signature or emission fingerprint that can be determined independently
and used to assign the proper contribution from that probe to individual pixels in
a lambda stack.
D. P. Singh et al.
tivity, selectivity, and large temporal range, fluorescence spectroscopy has proven
to be a basic tool to reveal the biomolecular dynamics. To study protein structure and dynamics, fluorescence-based methods have the following advantages:
(i) dynamics of a specific group or a segment of a massive macromolecular system
can be observed without interference from the rest of the system; (ii) the timescale
of observable dynamics covers a wide range from femtoseconds to seconds, and
(iii) observations can be made at very low concentrations. In a recent study, Blue
Light Using Flavin (BLUF) domains are attracting interest for use in optogenetic
constructs (Fig. 10c); however, the mechanism of their activation needs to be disclosed. By incorporating a tryptophan analogue, 7-aza-Trp (7AW) into the BLUF
domain, the functional dynamics of the crucial W104 residue can be investigated
during photoactivation of the protein [22].
• Fluorescence imaging modes in live-cell microscopy:
Monitoring the interactions among the cells as they grow is essentially important to understand organismal development. Fluorescence microscopy is the most
widely used tools for high-resolution, noninvasive imaging of live organisms and
organic fluorophores are the most commonly used tags for fluorescence-based
imaging. For labeling specific cellular proteins, fluorescent materials are conjugated to biomolecules that provide binding specificity (Fig. 10d, e) [23, 24].
Bioconjugation approaches vary with the surface properties of the fluorescent
material. The mixed surface self-assembly approach is recommended for conjugating biomolecules to fluorescent material capped with a negatively charged
surface ligand.
• Fluorescence spectral imaging, emission fingerprinting, and tumor detection:
The fluorescent materials are extensively employed in sensing and biomedical
applications. The labelling of multiple antibodies with various fluorophores permits visualization of different targets within a single image of multiple channels
(Fig. 10f). Nowadays, fluorescent materials can also be used such as diagnostic agents for tumor detection through tumor-specific membrane antigens (Fig.
10g), DNA-functionalized probes for real-time identification of disease-relevant
biomolecules, therapeutic efficacy, and molecular probes for simultaneous tracking and monitoring of drug delivery [25, 26]. An approach to measure FRET with
spectral imaging is termed as lambda FRET and has proven to be a highly specific,
sensitive, and robust method for analyzing resonance energy transfer in live cells.
The lambda FRET algorithm relies on imaging of a FRET specimen at multiple
emission wavelengths, followed by separation of the FRET spectrum into its donor
and acceptor components to obtain a pixel-based calculation of FRET efficiency.
In the emission fingerprinting application [27], each fluorophore or an absorbing
dye, regardless of the degree of spectral overlap with other probes, has a unique
spectral signature or emission fingerprint that can be determined independently
and used to assign the proper contribution from that probe to individual pixels in
a lambda stack.