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Introduction to the classification and characteristics of Cyanines series fluorescent dyes

We all know that there are many types of fluorescent dyes, such as: Cyanines, SIR, Fluorescein, TAMRA, ICG, etc. Today, I will show you one of them, Cyanines. For details, please see the following:

Cyanines-1

Cyanines-2

There are two types of cyanine dyes: non-sulfonated cyanines and sulfonated cyanines. For many applications, they are interchangeable because their spectral properties are nearly identical. Both sulfonated and non-sulfonated dyes can be used to label biomolecules such as DNA and proteins. The difference between dyes is their solubility: sulfur dyes are water soluble, and they do not use organic co-solvents for marking in aqueous environments. They do not tend to aggregate in water. In some cases, one type of cyanine is required.

Types of Cyanine dyes (non-sulfonated and sulfonated cyanines):

Organic inorganic light-emitting materials, optoelectronic materials, cyanine dyes, metal complexes, perovskites, synthetic phospholipids, polypeptides, polymer PEG derivatives, block copolymers, magnetic nanoparticles, nano-gold and nano-gold rods, electrospinning fibers Membranes, photoinitiators, photoresists, near-infrared fluorescent dyes, MAX phase ceramics, fluorescently labeled dextran BSA and streptavidin, protein crosslinkers, small molecule PEG derivatives, click chemistry products, macrocycles Ligands, fluorescent quantum dots, etc.

Features of Cyanines Fluorescent Dye:

Anthocyanins are dyes, green crystals. Soluble in alcohol and glacial acetic acid, slightly soluble in hot water, insoluble in cold water. It is red when dissolved in alkali metal carbonate, red in concentrated hydrochloric acid, and blue in aqueous solution. Anthocyanidin, also known as anthocyanin, is a kind of water-soluble natural pigment that exists in plants in nature. It is a flavonoid. class compounds.

Non-sulfonated cyanine dyes

Useful non-sulfonated dyes include Cy3, Cy3.5, Cy5, Cy5.5, Cy7 and Cy7.5. Cy stands for "cyanine", and the * digit represents the number of carbon atoms between the indolyl groups. Cy2, which is an oxazole derivative rather than pindoloning, is an exception to this rule. The suffix .5 is added to indicate benzo-fused cyanines. Changes in structure allow changing the fluorescent properties of the molecule and covering important parts of the visible and near-infrared spectrum with several fluorophores.

Cyanines-3

Most non-sulfonated cyanine derivatives (with the exception of hydrazide and amine hydrochlorides) have low water solubility. When these molecules are used for biomolecular labeling, organic co-solvents (5-20% DMF or DMSO) must be used for efficient reactions. Cyanine dyes are dissolved in organic solvents and then added to solutions of biomolecules (proteins, peptides, amino-labeled DNA) in appropriate aqueous buffers. When binding occurs efficiently, the dye reacts before precipitating. The fluorescence properties of non-sulfonated cyanines are very solvent- and ambient-dependent.

Sulfonated cyanine

Sulfonated cyanines include other sulfo groups that facilitate the dissolution of dye molecules in the aqueous phase. The charged sulfonate group reduces aggregation of dye molecules and heavily labeled conjugates. Currently available sulfocyanines include sulfo-Cy3, sulfo-Cy5 and sulfo-Cy7.

Cyanines-4

Sulfonated cyanines are highly water soluble. Labeling with these reagents does not require organic co-solvents.

Sulfonated and non-sulfonated cyanines show very similar fluorescence properties. But some differences should be noted. Non-sulfonated cyanines must be dissolved in an organic co-solvent (DMF or DMSO) and added to a solution of the target molecule in aqueous buffer prior to use. The recommended volume of co-solvent should be 10% for Cy3, Cy5, Cy7 and 15% for the .5 counterparts. Sulfocyanine reagents can be used in pure water. Purification also makes a difference: when purification is performed using water or aqueous buffer dialysis, sulfocyanine must be used to effectively remove unreacted dye. Reactions with sulfo- and non-sulfocyanines can be purified by gel filtration, chromatography (HPLC, FPLC, ion exchange) or electrophoresis.



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