Heptamethine dyes are a subclass of chemical compounds within the

cyanine Cyanines, also referred to as tetramethylindo(di)-carbocyanines are a synthetic dye family belonging to the polymethine group. Although the name derives etymologically from terms for shades of blue, the cyanine family covers the electromagnetic s ...

dye family and have many uses as

fluorescent dyes A fluorophore (or fluorochrome, similarly to a chromophore) is a fluorescent chemical compound that can re-emit light upon light excitation. Fluorophores typically contain several combined aromatic groups, or planar or cyclic molecules with se ...

, particularly in biomedical imaging, the development of

theranostics Personalized medicine, also referred to as precision medicine, is a medical model that separates people into different groups—with medical decisions, practices, interventions and/or products being tailored to the individual patient based on thei ...

, the individualized treatment of cancerous patients with the aid of PDT, co-administration with other drugs, and

irradiation Irradiation is the process by which an object is exposed to radiation. The exposure can originate from various sources, including natural sources. Most frequently the term refers to ionizing radiation, and to a level of radiation that will serve ...

.F. Pene, E. Courtine, A. Cariou, J.P. Mira. Toward theranostics. Crit Care Med, 37 (2009), pp. S50–S58 The characteristics of heptamethine dyes can be understood by comparing research data on different dyes within the family. For example, the IR-780 dye exhibits a peak spectral absorption of around 780 nm.

Optical properties

The absorption and fluorescence spectrum of heptamethine dyes are in the

near infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

region and vary largely on the solvent and concentration. IR-808 absorbs mainly between 775 nm and 796 nm and emits fluorescence between 808 nm and 827 nm with a large red shift as expected in the serum sample. These absorption rates are important for their medical applications due to the image capturing capabilities. Dyes with good

pharmacokinetics Pharmacokinetics (from Ancient Greek ''pharmakon'' "drug" and ''kinetikos'' "moving, putting in motion"; see chemical kinetics), sometimes abbreviated as PK, is a branch of pharmacology dedicated to determining the fate of substances administered ...

and

fluorescence Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...

above 680 nm are considered viable in biomedical imaging due to their significant tissue penetration and imaging signature relative to background frequencies.

Patents

International patents on the use of heptamethine dyes for use in photographic use have also been approved and instituted. Fuji film placed a patent titled “Heptamethine cyanine compound, near infrared absorbing ink, near infrared absorbing sheet and silver halide photographic material” in 1999 and a follow-up international patent 6072059 in 2000. Heptamethine dyes for near infrared fluorescent imaging are manufactured by such companies as Intrace Medical, Lumiprobe, Cyandye,

LI-COR Biosciences LI-COR Biosciences is an international biotech company which designs, manufactures, and markets instruments, measurement systems, and software for biological and environmental research, and develops relevant measurement methodologies and techniques ...

- GmbH and others.

References

{{reflist Cyanine dyes Optical imaging Theranostics