How to choose a suitable fluorescent labeling group depends on your experimental needs.
Pharmacological experimental research is basically divided into two categories: in vivo research and in vitro research. For in vivo studies, fluorophores with emission wavelengths of 650-900nm are generally selected, such as: ICG, Cy5.5 and Nile Blue.
This is because the fluorescence emitted by such groups has better tissue penetration ability and is less affected by background interference (water, hemoglobin and deoxyhemoglobin generally produce background interference absorption, and the area is about 560nm).
For in vitro studies, fluorophores with emission wavelengths between 400 and 600 nm are the most commonly used, such as AMC, FITC, and TAMRA.
Fluorescently labeled peptides are widely used in modern medicine. For example: use Cy5.5-labeled target peptide to study the binding effect on c-Met receptor.
Someone designed cMBP containing the sequence of KSLSRHDHIHHH, the C-terminus is GGGSC, and the C-terminus Cys is labeled with Cy5.5-Maleimide for its sulfhydryl side chain.
The results of the study showed that the Cy5.5-cMBP polypeptide and U87MG tumor cells after 24 hours of co-incubation, have a higher cancer cell uptake value, and its response concentration is at the nanomolar level.