DOI: 10.15129/8c15a89e-4b90-418b-b028-0292303c46db
title: Data for: "Freeze-drying cycle optimization for the rapid preservation of protein- loaded liposomal formulations"

description: This dataset support the publication "Freeze-drying cycle optimization for the rapid preservation of protein- loaded liposomal formulations". Technology such as the use of microfluidics to generate liposomes has been well researched, yet the stabilisation of liposomal formulations is a major challenge to their greater implementation. To the best of our knowledge, this is the first study investigating the use of 96 well plates to freeze-dry ovalbumin (OVA) loaded neutral (DMPC:Chol and DSPC:Chol), anionic (DSPC:Chol:PS) and cationic (DSPC:Chol:DOTAP) liposomes. Through the use of high throughput screening, a freeze drying cycle was optimised; ramp freezing from from 4°C to -45°C, followed by primary drying at -30°C and secondary drying at 30°C under a vacuum of 0.1 mBar. These parameters maintained liposome physicochemical properties, with the liposomes remaining below 100 nm and were homogenous (polydispersity index of less than 0.2 post rehydration). Minimal leakage of the OVA protein was observed, with almost 100% OVA remaining encapsulated post rehydration of the formulations. Here we have identified a simple method that allows for the rapid screening and freeze-drying of a range of liposomal formulations. The data supports the following figures. Figure 3: Characterising empty and OVA loaded (0.25 mg/mL) DMPC:Chol liposomes before and after freeze drying. The formulations were made using microfluidics at a 3:1 flow rate ratio and a speed of 15 mL/min, at either 4 or 10 mg/mL initial lipid concentration (represented by ‘L’). The OVA encapsulation efficiency (%) of DMPC:Chol liposomes (0.25 mg/mL initial OVA) are represented by the letter ‘P’. The liposomal formulations were mixed with either 5 or 10% final sucrose concentration (at a 1:1 liposome:cryoprotectant mixture) with the size (A) and polydispersity (B) measured. The results represent three independent batches, ± SD. Figure 4: Characterising empty and OVA loaded (0.25 mg/mL) DSPC:Chol liposomes before and after freeze drying. The formulations were made using microfluidics at a 3:1 flow rate ratio and a speed of 15 mL/min, at either 4 or 10 mg/mL (represented by L). The DSPC:Chol liposomes containing OVA are represented by the letter ‘P’. The liposomal formulations were mixed with either 5 or 10% final sucrose concentration (at a 1:1 liposome:cryoprotectant mixture) with the size (A) and polydispersity (B) measured. The results represent three independent batches, ± SD. Figure 5: Characterising empty and OVA loaded DSPC:Chol:PS (anionic) and DSPC:Chol:DOTAP (cationic) liposomes before and after freeze drying. The formulations were made using microfluidics at a 3:1 (anionic) and a 1:1 (cationic) flow rate ratio and a speed of 15 mL/min, at 10 mg/mL initial total lipid. The liposomal formulations were mixed with 7.5% final sucrose concentration (at a 1:1 liposome:cryoprotectant mixture) with the size (A) and polydispersity (B) measured. Figure 6: The characterisation of OVA loaded DMPC:Chol and DSPC:Chol liposomes before and after freeze drying. The liposomes either underwent ramp freezing or snap freezing as part of the freeze drying cycle. All samples were freeze dried in the presence of the cryoprotectant, sucrose (10% v/v at a 1:1 ratio). The results represent three independent batches, ± SD.