GrowDex® hydrogel consists of cellulose nanofibrils dispersed in ultra-pure water. In water, GrowDex® forms a strong hydrogel at low concentrations. The product is sterile and can be readily used for various cell culture applications. The pH of GrowDex® is 6–8. The product should be stored in the dark at 5–22°C (41–71°F), as it becomes unstable when frozen.
Diluting and mixing GrowDex with cells
The viscosity of GrowDex® can be adjusted by diluting the product to a less viscous state. Dilution can be made with e.g. cell culture media, PBS, or ultra-pure water. GrowDex® concentrations of 0.2-1.0 % are commonly used for cell culture applications, the optimal concentration depends on the cell type being used. After dilution the cells can be seeded either on top of, or in GrowDex.
EXAMPLE OF CELL SEEDING TO FORM 3D CELL CULTURE IN GROWDEX®
Working GrowDex concentration required = 0.5 %
Final volume = 1 ml
a) Pipette 567 μl culture medium into a test tube.
b) Add 333 μl GrowDex® and mix by pipetting up and down until the solution is homogenous by visual inspection. Low-retention pipette tips are recommended for this procedure.
c) Add 100 μl cell suspension to the diluted GrowDex® slowly and stir carefully using the pipette tip to evenly disperse the cells.
d) GrowDex® is now ready for use at a working concentration of 0.5 %. Transfer appropriate volume of hydrogel to well plate, and add culture medium on top.
Pre-diluted GrowDex® without cells can be stored for 7 days at 2-8°C if no unstable components are present in the media.
Tips for users
Please see our instruction video about GrowDex in 3D cell culture.
Recommendations for pipetting GrowDex®:
a) Low-retention pipette tips should be used to avoid GrowDex® sticking to the tip.
b) Aspirating and dispensing GrowDex® should be performed slowly to avoid air bubbles and to ensure an accurate volume.
c) For an exact amount of undiluted GrowDex® the product can be weighed before dilution.
d) Electric dispensing pipettes can be used for mixing that may reduce user-variability.
e) A positive displacement pipette is useful when pipetting undiluted GrowDex and a multi-stepper pipette is recommended for repeated dispensing of GrowDex® into the well-plates.
Recovering GrowDex® from the vial:
a) If GrowDex® has accumulated on the walls of the vial or water droplets are present then the vial can be centrifuged briefly to concentrate the product at the bottom for easier recovery.
a) It is recommended to use 96- or 384-well plates
b) Micro-plates containing GrowDex® should be handled with care. Avoid shaking when moving the plate between locations.
c) When culturing adherent cells, the use of low-attachment micro-plates or pre-coating with e.g. PolyHEMA, is recommended to prevent cells attaching to the bottom of the wells.
a) When changing the medium extra care should be taken not to disturb the top of the gel.
b) If loss of GrowDex® occurs then it is recommended only half the amount of media be exchanged at one time.