Product DescriptionLipi probes are small molecule which emit strong fluorescence in hydrophobic environment such as in LDs.

Function of lipid dropletsLipid droplets (LDs) are composed of neutral lipids such as triacylglycerol & cholesteryl ester that are surrounded by phospholipid monolayers and are seen ubiquitously, not only in adipocytes¹⁾. Although LDs were simply thought to serve as a lipid storage unit, a recent study has stated that LDs play an important role in regulating lipid metabolism, autophagy²⁾ and cellular senescence³⁾.Therefore, have gained great attention as an important tool to elucidate the mechanisms of formation, growth, fusion, and retraction of LDs.

1) T. Fujimoto et al., “Lipid droplets: a classic organelle with new outfits.” Histochem Cell Biol., 2008, 130(2), 263.2) R. Singh et al., “Autophagy regulates lipid metabolism.” Nature, 2009, 458(7242), 1131.3) M. Yokoyama et al., “Inhibition of endothelial p53 improves metabolic abnormalities related to dietary obesity.” Cell Reports, 2014, 7(5), 1691.

Only by the addition of a reagent, the imaging of lipid droplets (LDs) or the quantitative variation of LDs in live and fixed cells becomes quantifiable.

Lipid Droplet Assay Kit considerably shortens the entire process and can be used for live cells.The fluorescent dye provided in the Lipid Droplet Assay Kit can be used for live and fixed cells. Compared to a method of using a colorimetric reagent, the method of using the Lipid Droplet Assay Kit can shorten measuring time. Furthermore, the repeatability of experiment can be increased by using the Lipid Droplet Assay Kit because the dye is not deposited in a plate.

Experimental example of plate assayChanges in lipid droplets were examined after the addition of oleic acid or Triacsin C (acyl-CoA synthetase inhibitor) to the A549 cell culture medium.

As a result, we confirmed that the oleic acid-treated cells show an increase in the number of LDs, compared to control and Triacsin C-treated cells.

Blue　　 ：Ex. 376 – 386 nm / Em 435 – 455 nmDeep Red ：Ex. 623 – 633 nm / Em 649 – 669 nm

Reagent ComparisonChanges in lipid droplets were examined after the addition of oleic acid or Triacsin C (acyl-CoA synthetase inhibitor) to the HeLa cell culture medium.As a result, we confirmed that the oleic acid-treated cells show an increase in the number of LDs, compared to control and Triacsin C-treated cells.

<Detection Condition>Blue　　 ：Ex. 405 nm/ Em 425 – 475 nmDeep Red ：Ex. 640 nm/ Em 650 – 670 nm

Related Product Information

Preparing a stock solution of oleic acidRequired Reagents:・BSA (bovine serum albumin)・Oleic acid・0.1 mol/L Tris-HCl (pH 8.0)Procedure:(1) Dissolve 0.14 g/mL BSA in 0.1 mol/L Tris-HCl (pH 8.0).(2) Add 4 mmol/L oleic acid to a disposable centrifuge tube.(3) Add BSA solution (prepared in step 1).(4) Cap the tube and mix on a rotary shaker (Be sure the solution is transparent, indicating that oleic acid has been conjugated to BSA).(4) Filter the solution prepared above (step 4) using 0.22μm filter membranes.(5) Store oleic acid stock solution at 4˚C.*Use the appropriate amount of oleic acid stock solution for culture medium to prepare working solution.*Oleic acid working solution cannot be stored. Please prepare the working solution immediately before usage.

Inducing lipid droplets(1) Incubate cells for 24 hours at 37˚C in a 5% CO₂ atmosphere.(2) Add 200 µmol/L working solution (prepared from oleic acid stock solution) to culture medium and incubate for further 24 hours.