Direct q 5 uv equipment

L-α-phosphatidylcholine (PC) (Soy, 95%, Avanti polar lipids), rhodamine B (99%, ACROS Organics, NJ, USA), Ultra-purified water (18.2 MΩcm resistivity at 25 °C) was produced from Direct-Q 5 UV equipment (Millipore S.A.S. 67120 Molsheim, France). All reagents were used without further treatment.

Manganese(II) chloride (99%, Khimreaktiv, Moscow, Russia), EDTA (99%, Merck Millipore, Burlington, MA, USA), DTPA (99%, Merck Millipore, Burlington, MA, USA), branched polyethyleneimine (PEI) as 50% aqueous solution (M.n. 60000, Sigma-Aldrich Co, St Louis, MO, USA), sodium hydroxide (99%, Khimreaktiv, Moscow, Russia), and hydrochloride acid (99%, Khimreaktiv, Moscow, Russia) were used. Ultra-purified water (18.2 MΩcm resistivity at 25 °C) was produced from Direct-Q 5 UV equipment (Millipore S.A.S. 67120 Molsheim-France). Experiments and measurements were conducted at 298 K. The temperature was maintained using Haake DC10 (Thermo Fisher Scientific GmbH, Karlsruhe, Germany) cryo thermostat. PEI concentration is expressed in its “monomeric” units relative to the respective molecular weight. Water content was determined with thermal gravimetric analysis using TG Analyzer TG 209 F3 Tarsus (NETZSCH). Infrared spectra (4000–400 cm⁻¹) were recorded on a Scimitar FTS 2000 spectrophotometer in KBr pressed pellets.

Gadolinium(III) nitrate hexahydrate, Gd(NO₃)₃∙6H₂O (pure for analysis, Khimreaktiv, Russia), citric acid (ACS reagent, ≥99.5%, Sigma-Aldrich), branched polyethyleneimine, PEI as 50% aqueous solution, (PEIX, where X = 0, 1, 2, 3 for Mw 60 kDa, 25 kDa, 1.3 kDa, and 0.8 kDa, respectively, Fluka), poly(diallyldimethylammonium chloride), PDDC as 35% aqueous solution (Sigma-Aldrich), sodium chloride (chemically pure, Khimreaktiv, Russia), sodium hydroxide, nitric and hydrochloride acids (pure for analysis, Khimreaktiv, Russia) were used. Ultra-purified water (18.2 MΩcm resistivity at 25 °C) was produced from Direct-Q 5 UV equipment (Millipore S.A.S. 67, 120 Molsheim, France). Experiments and measurements were conducted at 298 K. The temperature was maintained using a Haake DC10 (Thermo Electron) cryo thermostat. Polymer concentrations are expressed in their “monomeric” units relative to their respective molecular weights.
A “Starter 3100” (Ohaus) pH-meter was used for measuring acidity values of solutions, and was calibrated using standard buffers (pH 4.01, 7.00 and 9.00); pH metric titration was performed using an A-600 autotitrator (Kyoto) with carbonate free alkali.