Why is our kit called 'Purple-Jelley'?
Discovering the J-Aggregate Effect in Cyanine DyesIn 1936, Edwin Jelley made a fascinating observation, documented it in a letter to Nature (Nature 138, 1009 - 1010). He noted a peculiar behaviour of certain cyanine dyes, that when dissolved in 5 M NaCl, they dyes exhibited a third absorbance peak at a longer wavelength, around 650nm. In deionized water, however, they displayed only a double peak at approximately 540nm and 570nm. The 650nm peak in concentrated dye solutions resulted from the aggregation of dye molecules and was later termed a 'J-aggregate,' in honor of Edwin Jelley. The J-aggregate is known as a supra-molecular complex, formed by stacking individual dye molecules.
Subsequent research in the 1960s, notably by Kay et al. (J. Physical Chem. 68, 1896 – 1906), revealed that various biological polymers, including proteins, DNA, polar lipids, and glycosaminoglycans, could also induce this third absorbance peak. This phenomenon led to the development of the Purple-Jelley assay, named after the purple color of the dye reagent and Edwin Jelley himself.
An overview of the Purple-Jelley assay steps:
During the assay, hyaluronic acid is selectively purified during the assay sample preparation protocol. This is then reacted with the Purple-Jelley dye reagent, and the absorption of the characteristic third wavelength recorded. By comparison with a calibration curve the hyaluronic acid content of the sample can be measured.
Step 1. The assay protocol takes tissue samples through a sequential sample preparation protocol which involves enzymatic protein digestion, followed by precipitation and purification of GAGs, culminating in the precipitation of purified Hyaluronic acid.
Step2. The processed sample is then incubated for 10 minutes with the Purple-Jelley dye reagent, forming a coloured product which can be measured spectrophotometrically.
Step 3. The Hyaluronic acid content of unknown samples can be calculated by comparison against a calibration curve prepared using a standard comprising hyaluronic acid (supplied with the kit).
A list of suggested sample types can be found under the 'Assay Specification' tab.