Comparison between radioactive and non radioactive microspheres Radioactive microspheres have been used for many years as the standard for measuring regional blood flow distribution in animal research models. Radioactive microspheres have many negative health, safety and environmental issues associated with their use – furthermore, the disposal of research material must wait for 23 half-lives of the most longest lived isotope used. Non-radioactive microspheres are safe, environment-friendly and research material does not require specific disposal methods. DYE-TRAK microspheres have been thoroughly tested by independent investigators and results published in peerreviewed journals (CIRCULATION, Vol.83, Num.3, 1991. Kowallik et al.). The testing has included the stability of dye attachment, completeness of dye recovery, and comparisons of DYE-TRAK with radioactive microsphere results. The studies demonstrated that regional blood flow can be accurately measured over a wide range of flow in different species using this costeffective, non-radioactive technique.

Safe, accurate, cost-effective Wide range of applications: All regional blood flow measurements An ideal solution for all your current and future research needs

Main functionalities of non-radioactive microspheres
Bioseb offers a variety of non-radioactive tracer microspheres for determination of regional blood flow distribution and particle deposition. Uniform-sized tracer microspheres are made of stable polystyrene latex cross-linked with DVB. These microspheres are marked with one of several unique families of markers and used to measure regional blood flow at different time points during the course of an experiment. Typically blood flow measurements are made using 15um diameter microspheres. Occasionally 10um microspheres are also used for blood flow applications. Various other sizes of tracer microspheres are available for other applications in a range of sizes from 3 to 100um.

Typical research applications for non-radioactive spheres
Microspheres find applications in a very large spectrum of research fields. They can be used for any study where volume blood flow is of interest. Following table offers an non exhaustive overview of typical applications for various domaines.

Brain	Differences in blood flow between the right and left brain, differences in blood flow to different areas of the brain
Kidney	Differences between the right and left kidney, differences in blood flow within each kidney, studies of acute renal failure
Heart	Regional blood flow differences for the myocardium or across the ventricular wall, myocardial ischemia studies, mapping of regions of the myocardium receiving reduced blood flow, studies of the relationship between blood flow and myocardial function, studies of blood flow changes stimulated by angiogenic drugs
Liver	Studies of liver blood flow including changes due to shunting, damage or injury
Skeletal muscle	Studies of muscle blood flow in response to exercise
Bones	Studies of blood flow to normal bones, as well as broken bones that are healing
Skin	Studies of blood flow to normal, damaged or burned skin
Lung/Airway	Studies of blood flow to normal or diseased lungs, studies of airflow into the lungs and airways
Fetal	Studies in blood flow to and within the fetus
Trauma	Blood flow to any of the above tissues due to induced trauma or injury
Medical Devices	Testing devices that augment or control blood flow
Pharmacology	Studies of the effects of drugs to regional blood flow in any of the tissues listed above

Two different systems are available: absorbance-dyed microspheres (Dye-Track) and fluorescent microspheres (Dye-Track "F")

Dye-Track System Polystyrene microspheres of highly uniform diameter are precision dyed with one of several possible colors. Using an injection of Dye-Track spheres into a perfusion line or the left atrium, regional blood flow can be determined. The spheres are recovered from tissue and blood samples by digestion and subsequent micro-filtration. The dyes are then recovered from the spheres within a known volume of a solvent and their concentrations determined by spectrophotometry. The original Dye-Trak is a family of 5-color microspheres colors that have become a standard for non-radioactive measurement of regional blood flow in research animals: white, yellow, eosin (red), violet, blue. See illustration beside for the absorbance spectrum of each color These are precision 15um polystyrene latex microspheres with a very accurately controlled size.

Dye-Trak VII+ is a newer set of seven absorbance colors that are now available in addition the the original Dye-Trak family: lemon, yellow, orange, tangerine, persimmon, berry, navy. The newer Dye-Trak VII+ colors have absorbance peaks that are narrower and sharper, with higher absorbance (typically 1.5AU/5000 in 100ul solvent).

Click here to see our tutorial about the recommended color progression for Dye-Trak VII+ Microspheres

Dye-Track "F" - Fluorescent microspheres
Bioseb also distributes Triton Technology Dye-Trak 'F' fluorescent microspheres. Fluorescent microspheres are a sensitive non-radioactive method of measuring regional blood flow by dye extraction. After recovery of the microspheres from the harvested tissue samples, the dye is extracted and quantified by fluorescence spectrophotometry. Fluorescent microspheres have been well documented in the literature.