Tetronic 1107

Materials. Tetronic 1107 (T1107) was a gift from BASF, with a reported composition per arm of 60 EO and 20 PO, HLB 18-23 and average molecular weight 15,000 gmol -1 . Inorganic nanoparticles of barium titanate (BT, BaTiO 3 ), with an average diameter of 200 nm were supplied by Nanostructured and Amorphous Materials Inc.
(tetragonal crystalline structure, 99.9% purity, ρ = 6.02 g•cm -3 ), while nanoparticles of 50 nm in diameter were supplied by Sigma-Aldrich (cubic crystalline structure, 99.9% purity, ρ = 6.08 g•cm -3 ).
Preparation of BaTiO 3 nanoparticles. BT nanoparticles present strong aggregation that leads to rapid precipitation in water. Surface modification of the NPs with βcyclodextrin (CD) was performed to overcome this problem, according to the twostep procedure described in a previous work, 39 consisting in the generation of hydroxyl groups on the surface by reaction with H 2 O 2 , followed by mixing with a 10 mM β-CD solution under vigorous stirring. The resulting nanoparticles are centrifuged and washed three times to remove reagents in excess and freeze-dried for storage.

Doxorubicin hydrochloride (99.9%) was purchased from LKM Laboratories (Argentina). Pluronic ® F127 (F127, MW ∼12.6 kDa, 70 wt % PEO), Tetronic ® 1107 (T1107, MW ∼15.0 kDa, 70 wt% PEO) and Soluplus ® (MW ∼ 120 KDa) were a gift of BASF (Argentina). TPGS (MW ∼1513 g/mol) was purchased from Eastman Chemical Company (USA), sodium deoxycholate (NaDC) was purchased from Riedel-de Häen ® (Germany). Doxil ® was purchased from Raffo Laboratories (Argentina). Tetrazolium compound [3-(4,5-dimethylthiazol-2-yl)-5-(3carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H tetrazolium], inner salt (MTS) and phenazinemethosulfate (PMS) were purchased from Promega Corporation (USA). All solvents were analytical or high performance liquid chromatography (HPLC) grade and were used following the manufacturer's instructions.