Fluorescent probes are molecules that absorb light of a specific wavelength and emit light of a different, typically longer, wavelength (a process known as fluorescence), and are used to study biological samples. The molecules, also known as fluorophores, can be attached to a target molecule and act as a marker for analysis with fluorescence microscopy.
All living organisms are made of at least one cell. Cells contain many components such as DNA, proteins and organelles. Because cells are so small, scientists use microscopes to visualize them. However, it can be hard to distinguish what is what without colour – this is where fluorescence microscopy comes in.
Herein, we introduce a novel strategy to generate fluorescent chemical probes for the selective detection of both enzymes and non-enzymatic proteins. Fluorescence turn-on can be achieved upon the binding of the fluorescent probes to the hydrophobic ligand-binding domain of the target protein. The fluorescent probes can be synthesized by incorporating an environment-sensitive fluorophore with a protein-specific small-molecule ligand (Figure 4). Environment-sensitive fluorophores have emission properties that are highly sensitive to their immediate environment. Typically they exhibit very weak fluorescence in polar and protic environments but show strong fluorescence and blueshifted emission in hydrophobic surroundings. The rationale behind this new fluorescent probe, design is that most of the ligand-binding sites in proteins are hydrophobic and hydro-phobic interactions constitute the principal thermodynamic driving force for the binding of small-molecule ligands to their proteins.
A suitable fluorophore platform is quite essential for fluorescent fluoride probes and may affect their biological applications and efficiency. The reported dyes for fluorescent fluoride probes include anthracene, naphalimide, pyrene, BODIPY, fluorescein, rhodamine, resorufin, coumarin, and cyanine
Fluorescent probes are powerful tools with vast potential for application in chemical biology. The specific characteristics of the main group of fluorophores coupled with the development of new techniques have boosted their investigation in various research areas. For instance, the necessity of fluorescent tags applicable in different studies of subcellular localization and mechanisms of action of bioactive compounds has increased the development of fluorophores and new synthetic protocols for application in medicinal chemistry.
In industry, fluorescent probes can be used to determine the content of impurities in castings, so as to control the quality of products.
In agriculture, fluorescent probes can be used to check the purity of agricultural products, identify the viability of seeds, detect the deterioration of agricultural products as soon as possible, judge the maturity of fruits and diagnose crop diseases and pests. In addition, fluorescent probes can also be used to detect the content of pesticides.
In biochemical research, fluorescent probes can label antigens, antibodies, and nucleic acids, detect the active sites of proteins, study the damage and repair of DNA base pairs and the chemical reaction activity of drug molecules, and complete the qualitative, quantitative, and structural research of biological compounds.
In inorganic analysis, the elements to be measured in inorganic compounds interact with organic reagents, and the complexes combined with fluorescent probes can emit fluorescence of different wavelengths under ultraviolet light, so as to determine the content of the elements to be measured.
Our chemistry experience is an asset when a linker-dye combination is not commercially available, allowing us to perform the synthesis and conjugation under one roof.
onal Protein labeling, Kinase signaling.
Drug discovery- antiviral nucleotides, Aptamer studies.
Figure 3 Indian Muntjac fibroblast cells by ZEISS Microscopy via Flickr.
Figure 4) Illustration of the fluorescent turn-on probes for selective protein detection. The mechanism is based on the binding of the ligand to a specific hydrophobic site in a protein, whereby the adjacent hydrophobic environment can cause the environment-sensitive fluorophore to exhibit stronger fluorescence. In the absence of target protein, the fluorescent probe has low fluorescence.
Figure 2 Absorption and emission (Author’s own).
Figure 1 Fluorescent probe technology.
Figure 5 Molecules of common dyes of fluorescent probes for fluoride.