3 January, 2023
- Cell laden constructs
- Formaldehyde solution (PFA) 36.5–38% (from Merck, SKU: F8775-25ML)
- Crosslinking Agent (for alginate containing bioinks)
- Hank’s Balanced Salt Solution with calcium and magnesium (HBSS+/+)
- 70% Ethanol
1. Preparation of 4% PFA
For alginate containing bioinks, the 36.5-38% PFA can be diluted in Crosslinking Agent with 50 mM CaCl2, to minimize the risk of the construct dissolving in the PFA. If not using alginate containing bioinks, dilute the PFA with PBS.
For suggested PFA, which is 36.5-38%, mix 1.1 mL of PFA with 8.9 mL PBS or 50 mM Crosslinking Agent to receive 10 mL 4% final PFA concentration.
Submerge the 3D bioprinted samples in the 4% PFA and fix the constructs for 2-24 h at room temperature.
Note: Adjust the time according to experimental needs.
Wash the constructs 3 x 10 min with HBSS+/+ at room temperature.
Store at 4°C in 70% ethanol or HBSS+/+.
Note: Samples can be stored in HBSS+/+ at 4°C for one month. For longer storage or if proceeding to embedding, keep in 70% ethanol. For staining of the whole cell-laden 3D construct it is recommended to store the samples in HBSS+/+.