Schilt Y, Berman T, Wei X, Nativ-Roth E, Barenholz Y, Raviv U. Effect of the ammonium salt anion on the structure of doxorubicin complex and PEGylated liposomal doxorubicin nanodrugs. Biochimica et Biophysica Acta (BBA) - General Subjects [Internet]. 2021;1865 (5) :129849. Publisher's VersionAbstract

Background In Doxil®, PEGylated nanoliposomes are created by hydration of the lipids in ammonium sulfate, and are remotely loaded with doxorubicin by a transmembrane ammonium gradient. The ammonium sulfate is then removed from the external aqueous phase, surrounding the liposomes, and replaced by an isoosmotic sucrose solution in 10 mM histidine buffer at pH 6.5. Methods We prepared PEGylated liposomal doxorubicin (PLD) with a series of ammonium monovalent salts that after remote loading became the intraliposome doxorubicin counteranions. We analyzed the liposomes by solution X-ray scattering, differential scanning calorimetry, and electron micropscopy. Results PLDs prepared with sulfonic acid derivatives as counteranion exhibited chemical and physical stabilities. We determined the effect of these ammonium salt counteranions on the structure, morphology, and thermotropic behavior of the PEGylated nanoliposomes, formed before and after doxorubicin loading, and the bulk properties of the doxorubicin-counteranion complexes. By comparing the structure of the doxorubicin complexes in the bulk and inside the nanoliposomes, we revealed the effect of confinement on the structure and doxorubicin release rate for each of the derivatives of the ammonium sulfonic acid counteranions. Conclusions We found that the extent and direction of the doxorubicin confinement effect and its release rate were strongly dependent on the type of counteranion. The counteranions, however, neither affected the structure and thermotropic behavior of the liposome membrane, nor the thickness and density of the liposome PEG layers. In an additional study, it was demonstrated that PLD made with ammonium-methane sulfonate exhibit a much lower Hand and Foot syndrome. General significance The structure, physical state, and pharmacokinetics of doxorubicin in PEGylated nanoliposomes, prepared by transmembrane remote loading using gradients of ammonium salts, strongly depend on the counteranions.

Shukrun Farrell E, Schilt Y, Moshkovitz MY, Levi-Kalisman Y, Raviv U, Magdassi S. 3D Printing of ordered mesoporous silica complex structures. Nano Letters [Internet]. 2020;20 (9) :6598–6605. Publisher's Version
Shaltiel L, Shemesh A, Raviv U, Barenholz Y, Levi-Kalisman Y. Synthesis and Characterization of Thiolate-Protected Gold Nanoparticles of Controlled Diameter. J. Phys. Chem. C [Internet]. 2019;123 (46) :28486-28493. Publisher's Version
Bekenstein Y, Vinokurov K, Keren-Zur S, Hadar I, Schilt Y, Raviv U, Millo O, Banin U. Thermal doping by vacancy formation in copper sulfide nanocrystal arrays. Nano letters [Internet]. 2014;14 (3) :1349-1353. Publisher's Version
Margulis-Goshen K, Netivi HD, Major DT, Gradzielski M, Raviv U, Magdassi S. Formation of organic nanoparticles from volatile microemulsions. Journal of colloid and interface science [Internet]. 2010;342 (2) :283-292. Publisher's Version
Elek N, Hoffman R, Raviv U, Resh R, Ishaaya I, Magdassi S. Novaluron nanoparticles: Formation and potential use in controlling agricultural insect pests. Colloids and Surfaces A: Physicochemical and Engineering Aspects [Internet]. 2010;372 (1-3) :66-72. Publisher's Version