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To determine the optimal siRNA volume for complexation with liposomes in a 2.5 mL solution with 10 mg/mL lipid concentration, consider the lipid-to-siRNA weight ratio, typically ranging from 5:1 to 10:1 [1][2]. With 2.5 mL of liposomes at 10 mg/mL, you have 25 mg of total lipid. For a 5:1 ratio, you would need 5 mg of siRNA. Assuming a siRNA stock concentration of 1 mg/mL, you would add 5 mL of siRNA. However, given the limited volume, adjusting the siRNA concentration or using more concentrated siRNA stock may be necessary [3][4].

Reference

[1] Evers, M., Wakker, S. I. v. d., Groot, E. M. d., Jong, O. G. d., Gitz-Francois, J. J., Seinen, C. S., Sluijter, J., Schiffelers, R., & Vader, P. (2021). Functional siRNA Delivery by Extracellular Vesicle–Liposome Hybrid Nanoparticles. Advanced Healthcare Materials, 11.

[2] Kulkarni, J., Witzigmann, D., Leung, J., Tam, Y. Y., & Cullis, P. (2019). On the role of helper lipids in lipid nanoparticle formulations of siRNA.. Nanoscale.

[3] Lechanteur, A., Sanna, V., Duchemin, A., Evrard, B., Mottet, D., & Piel, G. (2018). Cationic Liposomes Carrying siRNA: Impact of Lipid Composition on Physicochemical Properties, Cytotoxicity and Endosomal Escape. Nanomaterials, 8.

[4] Schroeder, A., Levins, C. G., Cortez, C., Langer, R., & Anderson, D. (2010). Lipid‐based nanotherapeutics for siRNA delivery. Journal of Internal Medicine, 267.